2. TO OUR READERS IN THI S ISSUE
Welcome to StarTuned, th e
magazi ne for independent se rvice
4 EYE ON EMISSIONS
technicians work ing on Mercedes- Automobile emissions are a hot topic among
Benz ve hicles. Your Mercedes-Benz environmentalists, drivers and tech nic ia ns.
dealer sponsors StarTuned and Mercedes-Benz vehicles utilize emissions
provides the information co ming systems, such as Exhaust Gas Recircu latio n,
your way in each issue. to reduce harmful pollutants.
Merc edes-Be nz wants to present th e
information you need to know to
diagnose and repa ir Mercedes-Benz 10 CAN WE GET ON THE BUS?
cars accurately, qui ck ly and the first Since the early '90s, Mercedes-Be nz has developed
ti me; text, graph ics, on-lin e and oth er its Controller Area Network (CAN) to control how
techn ica l sou rces comb ine to make
components communicate with each other and with us
th is poss ible.
through our Compact III or Basic. How ha s this evolved ,
Feature articles, derived from
and wha t does it mean to diagnosis and repai r?
approved compa ny sou rces, foc us
on be ing usefu l and inte resting.
Ou r digest of techn ica l informati on 16 CONTROL UNITS
can help you so lve unanticipa ted GO BACK TO SCHOOL
problems qu ick ly and expe rtl y.
Our list of Mercedes-Benz dea lers
Installing a new control unit to replace the fai led one is
can help you f ind Genu in e
only half the job . With various combinations of options
Mercedes-Benz Parts. available on the same model, the new unit has to learn
We wa nt StarTuned to be both which are installed and how to work with the m..
helpfu l and informative , so please let
us know just what kinds of features 26 TAKING STOCK IN BONDS
and other diagnostic services yo u'd
(CHEMICAL BONDS, THAT IS)
like to see in it. We' ll continue to
Ease of manufacture, shear strength and aesthetic body
bring yo u se lected service bull eti ns
from Mercedes-Benz and articles
lines are only some of the reasons Mercedes-Benz uses
covering th e different syste ms on chemical bonding for joining body panels. How can we
these ve hicles . duplicate an OEM panel seam?
Send you r suggesti ons, qu estions
or comme nts to us at:
StarTuned
31 GENUINE MERCEDES-BENZ
One Mercedes Drive PARTS ... NEARBY
Montva le, New Jersey 0764 5 Wherever you are in the United States, there's a nearby
Ph one: 1 800 22 5 6262, ext. 7112 so urce of genuine factory parts for your customers'
e-mail: Sta rTuned@mbusa.co m Mercedes-Benz vehicles.
StarTu ned is a quarterly publication of Mercedes-Benz USA, LLC (" M BUS A"). No par t 0 f th i s newsletter may be reprod uced with out the express wri tten permission of
MBUSA. Ed ito r i a I and Circulation Offices: 598 Pine Po int Dr ive, Ak ron, Ohio 44333. Caution: Veh icle servicing performed by untrained persons could re su i t i n s e ri 0 u s
injury to those perso ns or others Informati on cont ained in this newsle t ter is intended for use by trained, professional a u to repair technic i ans ONLY. This
informat ion is prov i ded to inform these technicians of conditions which may occu r in some vehicles or to prov ide informat i on wh i ch cou l d assist
them in proper servicing of these veh icles . Properly tra ined technic ians have the equ ip ment, tools, safety instructions, and know-how to perform repairs
correct ly and safe ly. If a co nd it ion is described, DO NOT assume that a top ic covered in these pages automatica lly applies to yo ur vehic le or that your ve hicle has
th at cond ition. StarTun ed is a registered trademark of MBUSA.

3. STARTUNED
Information for the Independent Mercedes-Benz Service Professional
December 2008 U.S. $6.00 € 1 2.50 Volume 8 N umber 4
Group Publisher Contributing Editor MBUSA Technical Production Manager
Christopher M. Ayers, Jr. Chip Keen Content Advisor Devon Ayers
cayers@ cmacomm.com ckeen@cmacomm.com Donald Roto lo dayers@cmacomm.com
Donald.Rotolo@mbusa.com
Senior Proj ect Director Contributing Editor Circulation Manager
Tamra Ayers Kerry Jonsson MBUSA Project Manager Joann Turner
tayers@cmacomm.com kjonnson@omacomm.co m Stephen Langelotti jturner@cmacom m.com
Stephen.Langelotti@mbusa .com
Editorial Director Contributing Editor List Consultant
Bob Freud enberger Tom Nash Art Director NFocus
bfreud@ cmacomm.com tnash@cmacomm.com Jef Sturm
jsturm@ cmacomm.com
:C--~~"""i8~ "'" ~
,.

4. Eye On Emissions,

5. P0400 And Beyond
Take a deep breath and enjoy the fresh air. which cause the formation of NOx.
It wasn't always this way. Since the 1960s, To counteract this, a small portion of
the automakers have made tremendous previously-burned exhaust gas is introduced
strides in reducing the air pollution their into the intake charge, diluting the charge
vehicles produce, and Mercedes-Benz has and knocking the top off the peak
always been in the forefront of this effort. temperatures, which cuts NOx.
Hydrocarbons (HC), carbon monoxide (CO) _ _ _ When EGR is not working the way it was
and oxides of nitrogen (NOx) make up the designed, NOx goes up and/or drivability
terrible trio of gases that have been targeted. problems can occur. Three-way catalytic
In this article, we'll look at what M- B has converters, of course, also reduce NOx, but
done with EGR (Exhaust Gas Recirculation) here we're dealing with the EGR system only.
to reduce the last, and what you need to If there is insufficient EGR flow, NOx
know to keep that system functioning. emissions will increase. Excessive EGR flow
Computerized engine managem ent allows promotes inefficient co mbustion and
for leaner air/fuel mixtures , which help keep misfiring. With OBD II, EGR systems are
HC and CO down. But these leaner mixtures monitored for their performance through
lead to higher combustion chamber tempera- a series of computer-controlled tests
tures in the neighborhood of 2,500 deg. F., called monitors.
Here is the layout of a
late-model EGR system.
The EGR valve is mounted
on the cylinder head. The EGR
solenoid is on the valve itself
The EGR pipe feeds exhaust
gases to the intake manifold.
StarTuned 05

6. What Are The Symptoms?
_ _ _ When an EGR system problem is
present, the symptoms often feel like
they're caused by something else. Pinging
can occur, which will lead to an increase
in NOx production beyond what even a
good catalytic converter can handle.
Most Mercedes-Benz engines have knock
sensors that inform the ME (Motor
Electronics) control unit if the engine is
detonating. The control unit then retards
The EGR valve and solenoid are ignition timing, but performance will be
sold as one unit. The large reduced. If EGR flow is excessive,
particularly at low rpm, it can displace
threaded opening is where the enough oxygen to cause misfiring. This
pipe that leads to the intake can lead to unstable id ling and hesitation.
Most of the time, excessive EGR flow does
manifold attaches. The liquid not have a significant effect on drivability
inside is carbon cleaning solution. in the highway cruising range - the EGR is
wide open at this point, depending on
engine load. It is in the lower rpm ranges
that the relatively small amount of EGR
gas has a significant effect. EGR problems
can feel like an excessively rich or lean
condition, and misfiring can also cause
you to mistrust the oxygen sensor signal
voltages and fuel trim readings .
_ _ _ On OBD II vehicles, an EGR monitor
will test the integrity of the system . It is
critical to understand how the ME control
unit determines how the EGR system
is functioning. This EGR monitor will deter-
mine if an EGR code is going to set. The
system also needs to determine if there is
insufficient or excessive EGR flow. If you
are using a generic protocol scan tool,
The MAP sensor is only used to you may only see the EGR code P0400,
indicating there is a general problem with
diagnose emissions-related systems the system . With Mercedes-Benz factory-
such as EGR and EVAP fiow issues. specific software, you can often retrieve a
more detailed account of a particular EGR
You can use the MAP to monitor failure. Either way, the Mercedes-Benz ME
manifold vacuum and the open the control unit is capable of determining if
there is an EGR flow fault often b efore
EGR valve. Watching the change in
there is any sort of a drivability issu e.
the vacuum reading will tell about
the fio w of the EGR system.
06 StarTuned

7. The First Steps
• •_ As mentioned earlier, an EGR flow
problem can fe el like an excessively rich
or lean condition . Also, too mu ch flow has
a more significant effect at idle than at
cru ise, so test the vehic le at id le. Making
the mixture leaner by creating a vac uum
leak wil l temporari ly smooth out a rough
idle if the mixture is too rich . By the same
token, adding propa ne to a lean-running
engine will temporarily smooth things out.
If EGR gases are involved, combustion Blocl<this EGR passage to eliminate
efficiency is reduced, not because of too the possibility of any exhaust making
much or too little fuel, but because of too
little oxyge n in the intake charge. EGR
it into the intake manifold. If the
gases have displaced some of the charge, engine runs smoother, you have a
so adding fuel or air wi ll not correct t he
mixture. It's the excessive dead (low
leaking EGR valve. VerifY that it is not
oxygen content) exhaust gases ki lling being opened by vacuum from a
combustion, not incorrect fuel mixture .
solenoid that's stuck.
Creating a vacu um lea k (to correct a rich
condition) or adding propane (correcting a
lean condition) is a quick way we can
prove we do not have a mixture problem .
If spark and basic engine are tested and
are satisfactory you should now start
thin king about excessive EGR flow at the
wrong ti me .
• •_ Removing the EGR va lve and blocking
off the passage is a way to definitively
eliminate the possibility th at exhaust is
affecting the mixture. If the idl e is better,
you know the EGR is stuck open, or that
vacuum is reach in g the va lve at the wrong
time. Yo u can attempt to "un-stick" it,
but repla cement is a more certain repair.
If vacuum is bein g applied to the EGR
valve at the wrong time , you need to
find out why.
_ _ _ The EGR va lve should not be open at Here we are monitoring the ground
idle with the vehic le stationary. Th e ME control of the solenoid. A reading of
contro l unit needs to see veh icle speed
before it allows recirculation . Th e contro l
I 2 V means it is not energized and
unit operates an EGR co ntrol so lenoid no vacuum will ~ow to the EGR
often mounted to the va lve itse lf. In lower
valve. When the ME grounds the
solenoid, the EGR valve should open.
StarTuned 07

8. EMISSIONS
rpm ranges, the solenoid is gradually opened
Vehicle 1209.365 Control unit IME-SFI 2.8 by pUlse-width modulated, or duty cyc le
IActuations contro l, of the solenoid. At highe r rpm, the
Y32 (Air pump sWltchover valve) . M33 (electric air pump) ( @ . EURO 3 . EURO 4 • 04 ) solenoid is fully grounded and the EGR valve
Y62 (Fuel injectors) receives maximum vacuum and opens all
M1616 (Throllie valVe actuator)
M3 ( Fuel pump) the way. Monitor the ground control of the
Y58/1 (Purge control valve)
Y58/4 (Activated charcoal canister shut-off va lve) ( @)
so lenoid, and if it is being grounded either
Y31/1 (EGR vacuum transducer) the ground contro l wire of the EGR solenoid
Mixture adaptation is shorted to ground, or the ME
Electric suction fan for engine or air cond ~ ioning
Fuel tank leak test ( @ ) -- is mistaken ly grounding the wire. If the
I gn~ i o n circ u ~ shutoffT1 /x (i gn ~ion coil(s)) solenoid is not commanded to ground, but
Y2216 (variable intake manifold switchover valve)
manifold vacuum is passing through the
solenoid to the EGR valve, then the solenoid
is stuck open and needs to be replaced. The
so lenoid and EGR valve are usual ly sold as an
assembly, so in either case they get replaced
F11
together. Remember a stuck open EGR valve
or EGR solenoid wi ll flow excessive exhaust
at idle and cause the engine to stal l or run
Having a Compact III at your very roughly.
disposal allows you to command
the EGR solenoid open. This not only The Other Side
tests the computer's ability to ground If flow is in sufficient, expect slight pinging,
the solenoid, but also allows you a failed emissions inspection with high NOx,
and/or a MIL (Malfunction Indicator Lamp) I
to test the EGR system while the indicating a code in the P0400 range. There
vehicle is in your bay. is usually no severe drivability symptom
associated with low EGR flow. The first test
to perform is to simply open the EGR valve
at idl e and see how the engine reacts.
Older engines with the EGR mounted on the
exhaust manifold usually on ly flow enough
When dealing with an insufficient
~ow EGR code such as P040 I or
P200 I you need to have a method
to test ~ow. As you can see here, the
EGR pipe is almost clogged. The ME
control unit can see this restriction
and ~ag the code. Cleaning out the
pipe will {Ix the problem.
08 StarTu ned

9. exhaust to produce a rough idl e. Newer engin es If the vo ltage increase is too sma ll , flow is
with EGR systems mounted on the cylinder head being restricted. You know the valve and
wi ll f low enough to cause the engi ne to sta ll right so lenoid are working, but th e EGR passages
away. It only takes 5 to 6 in. Hg to full y open t he (typically the pipe) must be blocked with
valve. The valve should also hold vacuum for a carbon deposits. A typical MAP sensor reads
few min utes. Chances are if the va lve is not 4.5 vo lts with the key on and th e engine off.
holding vacuum it is not open ing in the first Once you start the engin e, vacuum brings the
place an d you wi ll probab ly notice very little signa l vo ltage on t he MAP to just about 1.4
change in engin e performance. volt s. Hold the engine at 1,000 rpm (it wou ld
• • • Th e next step is testing the so lenoid . The st all at idle) and energize the EGR so lenoid .
solenoid receives ign ition-on power from the Th e engine should start to run roughl y imme-
vehic le's power distribution system. Th e ME diately. If not, thi s usually means the EGR
control unit grounds the EGR so lenoid to al low so lenoid is stickin g closed and may flag a
manifold vacuum into the EGR va lve. You can code for insufficient flow. Th e code sets in
either gro und the so lenoid yo urse lf with a jumper the sma ll amou nt of time the so lenoid is com-
wire, or if you have a Compact III, yo u can use manded open, but the ME does not see a
the Activations Menu to actuate th e solenoid. change in MAP signa l vo ltage - it should rise
Any resu lt less than a quickly sta ll ed engine to ju st about 3.0V while the EGR is ope n.
indicates a low-flow issue. In orde r to pass the De-energizing the so lenoid shou ld return the
EGR monitor for OBD II , you should eva luate th e engin e to a normal idle right away. Otherwise,
EGR system the same way the ME control check for a so lenoid or va lve sticking open.
unit monitors it.
Coming To A Conclusion
Testing the Flow
Once the repair is comp leted on OBD II
Since the early 1990s Mercedes-Benz veh icles ve hicles you have the choice of clearing the
have migrated away from CIS fuel injection and code and running a specific drive cycle to run
exclusively use LH or HFM mass airflow type the monitor tests, or driving th e ve hicle
systems. Testing EGR flow by monitorin g the through multiple drive cyc les until th e EGR
change in the mass airflow reading is very mon itor passes at least three times. If you
difficult. Mercedes-Benz chose to use a MAP are going to run monitors, remember to
sensor to monitor manifold vac uum not for fuel make sure the coo lant temp does not drop
contro l, but for diagnostic purposes. Through the below 80 deg. C, and keep the ve hicle speed
MAP signa l, the ME contro l unit ca n watch the below 60 mph to prevent getting kicked out
change in vacuum when the EGR is opened. If it of t he monitor tests. Yo u can use your
indicates 18 in. Hg at 1,000 rpm and the EGR is Compact III to see if the conditions are met
opened, the manifold vacuum will drop. The to run the monitor.
larger the drop in manifold vacuum, th e greater Select "Measures for initiating fault path
the flow of EGR gases. If the MAP signal change test s," then "EGR Diagnosis" whi le in th e ME
is insufficient, the ME co ntro l unit deduces that contro l unit and you wi ll see bar graphs
the flow is insufficient also, and a code is set. indicating engine tempera tu re and rpm
You can simulate this by monitoring the vo ltage cond itions that need to be met. Tip : Most of
on t he MAP sensor at 1,000 rpm and grounding the time the EGR monitor is run while th e
the EGR so lenoid. (Remembe r that when ve hicle and engine are under a steady and
man ifold vacuum is low MAP signa l voltage is long deceleration. Man ifold vacuum is at its
high, and as vacuum increases MAP signa l vo lt- highest, so it is easier fo r th e ME control
age decreases.) You shou ld see the MAP vo ltage unit to determine EGR flow. By running the
in crease over 1.5V as the manifold vacuum monitor wh ile driving, you ca n verify that
decreases and the engin e runs rough. your repair has addressed the prob le m. • • •_
StarTuned 09

10. FEATURE ARTICLE

11. What is the purpose of advanced technology? some instances, the brake switch input goes
What is t he downside? Nowhere are these ques- directly to the ABS/ ASR/BAS (Braking Assist
tions mo re relevant than in the automotive indus- System)/ESP modules. If each control unit that
try. The purpose of technology is to improve the needed it had its own brake switch you would
driving experience, safety, and fuel mileage, and need one for the brake lights, one for the
to reduc e harmful pollutants. The downside is ABS/ ASR, one for the cruise control, etc. But
ever more complex systems . When things are there are only two brake switch inputs . How is
working as designed, fine. But, as the saying the lighting control module informed to turn on
goes, "To err is human, to really foul things up the brake lights? The signals get on the CAN
takes a computer." (Controller Area Network) bus.
Comp uter-controlled systems have expanded
their role in modern vehicles. This has allowed
for such advancements as Motor Electronics
(ME), antilock braking systems (ABS), electronic
accelerator (EA) systems, and so on. The evolu-
tion of these various systems led to their integra-
tion. Coupling wheel speed inputs from ABS and
throttle position sensors from ME determines
wheel sli p under acceleration, and this slippage
can be controlled by applying braking force to a
particular wheel and/or by limiting power by
means of the EA. This integration results in
Anti-Slip Regulation (ASR). Include in the
equation computer-controlled suspension and
you have the Electronic Stability Program (ESP).
In later years, this in tegration has expanded to
include all computer-controlled systems. Body
controls need to talk to one another during cer-
tain functions. On convertibles, for example, the
door con t rol units need to be informed that the This is a wiring diagram of one
top is bei ng opened so it can lower the windows
slightly to eliminate interference with the top. By of the first Mercedes-Benz CAN
pulling on the door handle, the central locking systems, including control units for
system also informs the door modules that the
door is being opened so the windows can be the powertrain. The DIIKSS (N I13
opened enough so that they don't rub against
the door seal.
ignition), LH-SFI (N31 I fuel injection),
As well as talking with other body control units, CCIISC (N413 Cruise & Idle), TCM
these computers may have to talk to powertrain
co ntro l units. We wouldn't want someone open-
(N /51 / transmission) and
ing the convertible top while driving at 60 mph. Diagnostic Module (N59 OBD I) are
The ABS/ ASR control unit must pass on the
vehicle speed to the body system control units to all communicating on this network.
prevent unsafe operation.
To save weight and wiring complexity, control ~ -':-'
units have been strategically placed throughout
the ve hi cle. However, testing something as sim-
ple as brake light failure has become complex . In
Stal"Tuned I I

12. CONTROLLER AREA NETWORK
software, through the use of a Compact III or
The Bosch bus
Basic , is very good at iso lating communication
problems. Thi s is due to the design of the CAN
Separate computers need to communicate
protocol through error hand ling, bit timing and
with one another to perform these integrated
synchro nization.
functions. In Mercedes-Benz veh icles, the
co mputers communicate through a CAN.
CAN Protocol
Robert Bosch developed this form of serial
co mmunication starting as early as '83, and a
commerc ial vers ion was ava il ab le in '86. Mercedes-Benz ve hicles can have multiple
Mercedes-Benz was there during the Controller Area Networks. For powertrain
development phase of the CAN protoco l. systems, these may include:
Serial-type communication means messages (in
our case, 11 bit or 29 bit) travel over a single • ME Motor El ectron ics
wire. Paralle l bus communication, on the oth er
• ETC El ectronic Tran smission Contro l
hand, means each bit needs its own wire to trav-
el down from one processor to another, which • ESM El ectron ic Shifter Module
would resu lt in a lot of extra wiring. Seri al com-
munication is what's used in a network of PCs. • ESP Electronic Stabi lity Program
Analog or digital inputs are processed by a
• SAS Sem i Automatic Suspension
contro l unit for its own use . The unit th en ge ner-
ates bus communication through square onloff • CGW Centra l Gateway Module
signals. If another contro l unit needs some or all
of the information on the CAN line, it determines Mercedes-Benz CAN protocol is sent out on a
what information it needs and uses it for its ope r- two-wire twisted pair integrated into the wiring
ation and its output controls. This contro l unit harness . One wire carries the CAN High signal
may also have inputs it puts out on t he CAN for and the other carries the CAN Low signa l. The
the use of other control units. All contro l units in CAN High signal starts off at .65 volt when it is
any particular network can share information via at ground , and th e square waves rise to about
th e CAN. 2.5V. The CAN Low signa l starts off communica-
What if the CAN were to "go down" and not tion at 4.65V when high and 2.5V when low. The
transmit information? The control units cou ld not two signa ls are identical in so far as square
communicate and needed information wou ld be waves are conce rn ed, except that one signa l
lost. Most functions requiring inputs from mu lt i- switches high (CAN High) and the other signal
ple cont rol units would not work. Thi s wou ld switches low (CAN Low). If you were to scope
include something as basic as startin g and run- both signals on a dual-trace lab scope, they
ning the engine. Without the Drive Authorization would appear to mirror each other. If a condition
System (DAS) approving the ign ition key, the ME existed that interrupted either the CAN High or
control unit wi ll not all ow the veh icle to crank Low signa l, an emergency mode would take over
and/ or nm. So, these networks must be kept up and the comp uter wou ld communicate over the
and running fo r the vehicle to perform as the CAN line that is sti ll functioning and set fault
Mercedes-Benz engineers designed it, with all of codes in each control unit on that particular
its safety features and creature comforts. CAN. If both CAN H and CAN L lines are shorted
We need to have a diagnostic plan for when con- to power or ground, commun ica tion wou ld be
tro l unit communication is lost. We will need to lost among al l contro l units on that CAN.
kn ow the pathway of CAN commun ication and The wirin g among all the control units is wired
how to test these signa ls. What often surprises in parallel. This means each control unit receives
automotive technicians is how simpl e these sys- the same CAN High and Low signal. In 1992 on
tems are to diagnose. Mercedes-Benz SDS the 140 chassis, the CAN wires we re spliced
12 StarTun ed

13. Locate the bridge
connectors under the
carpeting and interior
molding, and you can
test voltage signals.
Unplug suspect control
units and verify there
is no corrosion from
moisture, coffee, soda,
etc. In this case, you
can unplug the
connector to isolate
the ME control unit.
together at each contro l unit. If you are going to sp lices are named "Z" spl ice packs. Also in '96
test the CAN, you will need to get to a co ntro l on th e newer chassis, bridge co nnectors are
unit on the engi ne CAN, otherwise known as used to lin k the CAN wirin g. This can prove help-
CAN C. Th ere is a terminating resistor on this ful when diagnosing CAN commun icat ion prob-
CAN lin e. If you we re to unplug the LH-S FI (fuel lems that are the res ult of problem wiring. We
inj ection), or the DI/KSS (Direct Igniti on) co ntrol ca n access the CAN directly at severa l different
units and measure resistance between the two areas whe re these sp lice packs or co nnectors
CAN wire s at that con nector, you wou ld read are located . We often try to go to the eas iest
approxim ate ly 120 ohm s. When unplugging either point we can access.
the CC/ ISC (Throttle Module), Transm ission Mercedes-Benz uses multiple CANs. The pow-
Control Module (TCM), or the Di agnostic Module ertrain CAN is CAN C. Th e Body CAN is CAN B.
and chec kin g resistance between the two CAN Th e diagnosis CAN is referred to as CAN D.
wires, you sho uld read app roxim ate ly 60 ohm s. Th ere can also be a MOST bus, but th at is a fiber
Remember, only one co ntrol unit at a time optic network that we will cover in anothe r arti-
should be unplugged to perform this test. Th ese cle. When eva luating co mmunication problems
contro l units are difficult to scope for the CAN H betwee n contro l units, yo u shou ld find out which
and L signa ls sin ce the connector faces down ones are on that particular CAN, and, using your
and the sp lices are underneath the co ntrol units Compact III or Basic, try to commu nicate wit h
in the hou sing. each control unit that is connected. You shou ld
Starting around '96, th e CAN wires we re be able to co mmuni cate with eac h unless the
sp li ced together. On the wiring diagrams these bad contro l unit is shortin g the CAN lines to
StarTuned 13

14. CONT ROLLER AREA NETWORK
When testing for
battery drain, look at
amperage draw after
the vehicle has been
shut off for several
minutes to be sure all
the control units have
gone to sleep. The
normal procedure of
unplugging fuses to
locate the draw must
be augmented by
unplugging control units
from the CAN for the
some purpose.
power or ground. A contro l unit that is simpl y not Other Possible Problems
responding will not bring down communication
on th is CAN . The reaso n is that the computers all A breakdown of CAN commun ication among
wa it for an empty CAN t ra nsmission line and contro l units is not the on ly proble m that can
the n put out the information that has changed. occur. CAN commun icati on requires electrica l
Other control un its wait and only pick up the power. If these contro l unit s were to active ly
information they need out of the transmitted communicate with the ignit ion key off, the
message. The original message is still on the current draw wou ld discharge a ba ttery.
CAN and can be picked up by other contro l Overnight, your customer might wake up with a
units . dead battery even though nothi ng was left on.
If in the event t he CAN is down, you wi ll need With the ignition off, control units no longer need
to start disconnecting control units to see wh ich to communicate as much info rmat io n so they
is at fau lt. With al l the control units on a particu- slow down. Also with the ignit ion key off, either
lar CAN, th is can be time-consuming. Find the the EI S (Electronic Ignition Switc h) or t he CGM
bridge connectors for the CAN, typica lly la be led (Central Gateway Module) senses this and sends
X30 / #. These connectors are usually located at out signals to put contro l units into a "sleep" or
the base of the "A" pillar below the passenger's power-down mode . The Central Gateway Module
and driver's side kick panels. If the doors are not is often mounted under the in strument cluster on
properly sea led and water gets into the cabin, the lower panel by the driver's fee t. This contro l
corrosion can interfere with digital vo ltage unit is in charge of managing the different CAN
communication signa ls. When accessing these messages between different CANs. This allows
conn ectors, check fo r moisture in the area. information on CAN C to be passed on to CAN B,
1 StarTuned
4

15. To see if the CAN
lines have an electrical
problem with the wiring
you can get access to
the CAN lines (there
under the fuse box in
a 140 chassis) and
measure resistance
between CAN low and
CAN high. Since there
are two terminating
resistors in the circuit in
two of the control units
you should measure
about 60 ohms.
and so on . Previous to the introdu ct ion of this unplugging a contro l unit's CAN wiring, wait a
module, the EI S was the gateway and managed few minutes before check in g the CAN signals
CAN commun ication. Putting the contro l units to or vo lta ges.
sleep red uces current draw to und er 50 ma ,
wh ich is low enough to not kill a battery even In conclusion
after seve ral weeks. As mentioned earli er, the
CAN H si gnal osci ll ates between .65V and 2.5V, Com muni cat ion prob lems are not that hard to
and CAN L osci ll ates between 4.65 and 2.5 diagnose. Thanks to the engineering and design
vo lts. Wh en the contro l units go to sleep, the of the CAN protocol, you shou ld still be ab le to
CAN vo ltages change. CAN H drops to .025V and use your Compact III or Basic to comm unicate
CAN L inc reases to 11 V. Th ese vo ltages are with all the control units on the CAN until you
mainta ined for the durati on of the sleep period. find the one that's "incomm unicado." Very often
Th e vo ltage may see m high, but the cu rrent draw the oth er cont rol units will have diagnostic
is very low. trouble codes indi catin g the co nt rol unit is not
If any control unit were to cont inue transmit- commu nicating. In the event that one CAN line
ting digita l messages, the EIS or CGM would not is down, it can co mmuni cate with the other
reque st the contro l units to go to power-down CAN lin e. You can test the resistance of t he
and the ve hicle's battery would discharge. You terminating resistor, and unplug sp lice packs
can check vo ltage or scope the signals and see and bridge con nectors to iso late faulty wiring.
if the CAN lines powe r down. You will sti ll have The use of a scope or vo ltm eter can estab li sh if
to access t he spl ice con nect ion and bridge t he CAN is powerin g down, and unplugging
connectors to unplug each contro l unit' s CAN bridge connectors will iso late the control unit
wirin g until th e CAN goes to sleep. After that may be at fault.
StarTuned 15

16. FEATURE ARTICLE
Installing a new control unit
to replace the failed one is
only half the job. With various
combinations of options
available on the same model,
the new unit has to learn
which are installed and how
to work with them.
Control Units Go
Computer systems are everywhere t hese days. contro ll ed systems is as important as diagnosis -
We have separate control modules strategica lly - once you know what's wrong, you must be able
placed all over the veh icle. There is good reason to fix it. If the repair invo lves the rep lacement of
fo r this. Excessive wi rin g can increase the we ight a contro l unit, there are a few necessary steps
of a vehic le, make assemb ly diffic ult and render needed to comp lete the job.
diagnostics complicated. If wiring can be
reduced, the problems assoc iated with these In Concert
th ree concerns dimin ish. By placing modules
closest to the hardware components they con- Very often, a contro l unit works in concert with
tro l, wiring can be minimized. several other control units because they are all
As with any other techno logical advances, on a CAN (Contro ll er Area Network) . Together,
there is a teeth ing period. A technic ian's abi lity they provide a system of contro ls for the veh icle.
to diagnose a problem needs to play catch-up As ide from computer contro ls of the systems
with this progress. Properly servicing computer- they are ded icated to, they ca n share inputs and
16 StarTuned

17. Bacl<To School
Vehicle 1
211.065 Control ~nit IETC
iElectronic transmission control (722.6 EGS52)
With the old control unit
Control lIIlit version still in the vehicle and on
Fault codes
Event memo
Actual values
approved programming
Actuations
Imllal startup
charger attached to the
Control llllit adaptations
Initial test ( O~ cond~ion check I Oil level check battery, plug in the
W" rranty or goodwill processing
Adaptation Compact II, enter the unit
Diagnosis routines
Complete list of guided tests
FuU list of fautt codes and events
you wont to code, then
Special fUTICtion
~ Control unij log
select "Initial Startup."
;..r Sel''ice information and IIp-tc-date trollble diagnosis
roub leshooting by means of complaints or symptoms
Continued on page 20
Stal-Tuned 17

18. Replace - We replace more parts than aftermarket brands.
Engineered - Designed to meet original OEM drawings.
Manufactured - Made with same OE components as factory parts.
Assembred - Completely assembled from components and not just repaired.
Improved Technician Efficiency

19. 260E 1987-1989
300CE 1988-1993
300EfTE 1986-1993
300SE/ SEL 1988-1991
300SL 1990-1993
MODELS
A 0002300511 80 35OS0 1991 C240/C320/S430
350S0L 1990-1991 AOOO 230 91 11 80 S500/C L500/C LK320
2004
E320 1994-1995
SL320 1994-1997 E320/E500 2003·2006
SL600 1996-1997 A001 2301211 80
CLS500 2006+-
400E/500E 1992-1993
500SL 1990-1993 ML350/ML500/ML55AMG 2003+-
A 00023006 11 80 E420 1994-1995 A001 23028 11 80
E500 1994 G500/G55 (NOT G55K) 2003+
SL500 1994-1999
A001 2306811 80 ML320/ML430
1900 1986·1989
1900T/3000Tl TOT 1987 S55AMG/CL55AMG 2003-2005
190E 1985-1993
1987-1989
AOOO 230 90 11 80 C240/C320 UPTO 2003
260E
300CE 1988·1989 CLK320 2003
A 000 230 1111 80 3000 1987-1993
300E 1986-1992 AOOO 230 78 11 80 C32AMG KOMPRESSOR 2002·2004
300SE 1988-1992
300SEU TE 1988-1991 C230K M271
E3000 1995
AOOO 230 97 11 80 (VIN RANGE SPECIFIC)
2004
C2201 C280 1994-1995 S600/CL600 2001+
A 0002301311 80 C36AMG 1995 A001 2300111 80
S65AMG/CL65AMG 2005+
300S0 1992-1993
E55AMG 2004-2006
3005E/ 600SEC 1993
6005EL 1992-1993 CLS55AMG 2006
A 000230 17 11 80 S3201 S3500 1994-1995
S420 1997-1999 A001 2301411 80 E350/E550 2007
5600 1994-1996
CLS550 2007
CL600 1998-1999
S320 1995-1999 E320CDI 2005-2006
A 0002302211 80 S3500 1995
CLK550 2007
S600 1996·1999
CLK55AMG 2003+
1900 1986-1989
A001 2301911 80
1900T/30001 OTI TOT 1987 SLK55AMG 2005+-
190E 1985-1993
260E 1987-1989 C55AMG 2005+-
A 000230 2411 80 300CE 1988-1989
300E 1986·1992 2004
300SE 1988-1992
300S0L 1986-1987
300SEU TE 1988-1991
420SEU 560SECI SEL 1986-1991
A 000230 2511 80 560SL 1986-1989
400SE 1992
400SEU 500SEC 1993
A 119 230 00 11 80 500SEL 1992-1993
5420/500 1994-1995
C280/C43 AMG 1998-2000
CLK320 1998-2003
CLK430 1999-2003
CLK55 AMG/ML320 2001-2002
A 000230 70 11 80 E320 1998-2002
E430/E55 AMG 2000-2002
ML430 1999-2001
ML55AMG 2000
SLK230/SLK320 2001-2004
CL500 2001-2003
CL55 AMG 2001-2002
A 001 230 0211 80 S430

20. CONTROL UNIT TESTI NG Continued from page 17
Vehicle 1211.065 Control unit IETC
VIN read out from vehicle: WDBUF65,
VIN stored in control module: IWDBUF65J03A156573
You should see this
Enter VIN as a 17-digit code.
For example: screen indicating
WDB2200631A123456
USA, Canada: WDBNA63JOXA123456 the vehicle's VIN.
Hit the synchronize
NOTE:
The VIN stored in the control module must match the VIN read out from the vehicle. button to retrieve
F7 - Perform synchronization. the VIN, then
F5 - Confirmation of the VIN entry.
confirm that the
number is correct.
request output contro l. For examp le, there is no Flash!
need to have a separate air temperature sensor
for engine management if you can share informa- If a problem in the software of a contro l unit is
tio n with the one that is dedicated to automatic detected through warranty c la im s or other
climate control. The ambient air temperature means, Mercedes-Benz will generate an updated
sensor is one of the in puts used to ca lcu late the program to repair the trouble. Thi s is particularly
need for air conditioning or heating. That control important with ME (Motor Electron ics) and ETC
unit can be designed to pu t its temperature read- (Electronic Transmission Control) as em iss ions
ing on t he CAN where others can take it off. and sh iftin g concerns need to be add ressed (fue l
Today, more of th is cooperation is needed than formulas and driving styles can change). To be
ever before. If a contro l unit is changed, it must ab le to make these changes without provid in g an
learn what others are on the CAN so it can send entirely new ECU requires something ca ll ed
and rece ive the necessary information. Thi s is "Flashing." Thi s is done by means of the SDS
accomp li shed through coding a contro l unit. updating the software in the existin g contro l unit.
When a new replacement is in sta ll ed, the original No physical parts need to be replaced. This is
coding information from the old unit must be advantageous for everyone invo lved sin ce a con-
installed. Up to now, coding was achieved with trol unit often has multiple roles that would also
the SDS, but soon coding wi ll be available using have to be initia li zed in order for them to
a J2534 Pass-Thru device. With the SDS, you function properly. If you needed to replace
need to remove coding information f ro m the orig- instead of re-flash an ME contro l unit, you wou ld
inal control un it, then install the new "non- also have to relearn the anti-theft system
coded" model, and, finally, put this information between the EIS (Electron ic Ign it ion Switch)
on the new unit. Sounds simp le enough, and the ME contro l unit. By only re-flashing the
but th ere is a spec ific procedure that must software you el imin ate the need to align the
be fo ll owed. anti-theft information with the ME unit.
20 StarTuned

21. - ~,' -,
-- -.. - _......
Sho~d -thE!;:&bfug~~r a:liW~{9~~ ~~' ~-".-
I _ I .. _' _ _ "'-
I _ .... 0 _ - " -_ _ '"'_~ --
- I
Smal l sc ratches, stone impacts, dents and blemi shes -
and the customer's Mercedes can quickly lose the shine
from its exte rior. And because that is annoyance enough,
we keep the costs for a repair as low as possible - with
Mercedes-Benz Small Repair. Special repair methods mea n
that small appea rance defects vani sh in next to no time.
It goes with out saying th at our kits meet the high, tested
Mercedes-Benz quality stand ard s that yo u ex pect. So if your
customers are driving around with a small imperfection , it
may be able to be repa ired with Mercedes-Benz Small
Repair. Sma ll Repair Kits are available from your authorized
Mercedes-Ben z dealer.
Training on th e Small Repair method s are available from
Reliabl e Automotive Equipm ent. Please contact Reli able
Automoti ve Eq uipm ent to inquire about training your
staff to perform these repairs quickly and effici entl y.
R1:UABLE AUTOMOTIVE [Ql,JIPMENT. INC. 1.800.328.7855
StarTu ned 21

22. CONTROL UNIT TESTING
Vehicle 1211.065 Control unit IETC
Iinitial startup with automatic takeover of settings of previous cont At this point, you need
The following procedure will guide you through all steps required to perform a com
of system ETC.
to hove the old control
Preconditions : unit still plugged in.
- The old control un~ is still installed.
- The new control un~ must be available. Selecting "Initiol stortup
You will be guided through the following steps :
- Read coding and adaptation data and transfer these to new control module.
of 0 new control unit"
will leod you to this
Start process with button F2.
screen. Follow the direc-
tions ond the existing
coding will be reod from
the old unit.
More On Control Unit Identity tro uble codes for it. Th is will turn on warning
lights on th e dash indicatin g th at the re is a prob-
These sof twa re changes have spec ific tasks to lem. By the sa me token, if eit her an ME or ETC
either correct or im prove th e driva bility of a co ntrol unit is replaced and th e SC N is not
Mercedes-Benz. In th e case of th e ME or ETC, updated to match the vehi cle, this is co nsidered
th ese programs have a specific effect on the t ampe ring even if no perform ance modifi cati ons
overall em issions produced by the veh ic le. Th ey are performe d. Thi s means with each new re-
are therefore monitored by kee pi ng track of soft- flas h, the SC N need s to be updated as well.
wa re calibrations and givin g them a specific iden-
tity. Th is is accomplished with th e use of an SC N
Are You Ready?
(Software Ca libration Num ber). If it effects emi s-
sions, the EPA must be aware of t hese changes When repl acin g a c ontro l unit, yo u need to
in software and approve the m. Sin ce eac h co n- co de it to th e vehi cle . Thi s is achi eve d usin g you r
trol unit has a SC N, yo u ca n find out th e leve l of Comp act III or Basi c . Before st arti ng any co ding
softwa re in the vehic le, and determin e if a newer or prog ramming, you mu st have an approved bat-
release is available, or if t he latest softwa re is tery cha rger co nn ected to the veh icle to keep
alrea dy installed. vo ltage stea dy during the procedure. Aftermarket
Since 2003, SCN coding has bee n requ ired by co mp anies make programmin g battery chargers
federal law. The SC N indicates if any t ampering ava il abl e th at are ca pabl e of re acting to sudden
has occurred within the software of the co nt rol vo ltage drops ca used by th e co ntro l units switch-
unit. Aftermarket com panies that offer perform- in g on va ri ous componen t s. Traditional ba ttery
ance mod ifications usuall y do not meet the chargers react too slowly for th is purpose, so yo u
approva l of the EPA, and are co nsid ered for off- mu st make th e investment.
road use only, such as raci ng. Th ese perform- Yo u have two option s when cod ing. You ca n
ance "ch ips" or re-fl ashes, are ill ega l by st ate either downl oa d th e old contro l unit's existing
and federa l standards and shoul d not be used in softwa re whil e it is sti ll in sta ll ed in the vehicle,
cars driven on pub li c roa ds. These control uni ts plug in the new unit and then upload the old
wil l not have the necessa ry SCN to match th e softwa re into the new unit. If you have tota lly lost
res t of the vehicle. Other co ntrol units will see co mmuni cati on with th e old un it, you can insta ll
the differences in t he SC N an d fl ag diagnosti c the new one and "write" mode l and codi ng
22 StarTuned

24. CONTRO L UNITTESTI NG
Vehicle 1211.065 Control unit IETC If yo u have lost communication
IW rite model designation and equipment codes to control unit ETC.
Thor. Is no model doslgnrion ~nd no equlpmont codo ~ o (.d in cQnlrOil unit ETC. with the old control unit, you can
'''''del da.;gnaooo 121 106 5
write model designation and
TtM;mi;;ion-rlilhi... Ml9quipm9nt Codlil 1 14 91 • USA -
- equipment codes yourself Here,
Transmis'Sion;elevad equipment code 2
I -1
the country code is being select-
Control module dat;e
032 . TaiNan Cars
.- ed. Yo u may be asked questions
Function -softw8fe: ~
Data ut fe 1z
MB obj.<t nunilor. 0300404032
494 . USA C"Uforn i"
498 - Japan CSI S: on the options the vehicle has. If
Pushbutton F3 Write model dMigMIion and e-quiptnent eode~ to control unil
ZV4 - MtG vc1riiJnt Japan
"'·CI...
839 • Japo" G-CI•••
,
you don 't know all the answers,
these options will not function .
~j:j !J
=r: sran i!!!m!I c .. ~ (11 « r .: <l""_ll .. :! p_~ Eli L - rj Jll
-::-'& '.I :
-
information yo urself. This second option is
difficu lt since yo u need to be fam il iar with all of
the options installed on the veh icle, as we ll as
those that are not.
Using SDS, se lect t he contro l un it yo u wou ld
li ke to rep lace. Wh ile under that head ing, select
"In itia l Sta rtup ." You will be directed to a screen
showing no VIN in the new contro l unit. After ' .
synchroni zi ng with the other units, you shou ld
read the veh icle VIN and confirm the entry.
Next, select "Initia l Startup of a new contro l
unit," and the next screen wi ll gu ide you through
the process of rep lacement. The first step is to A new worldwide Mercedes-Benz
read the existing coding information . Afte r th is is anti-theft policy went into effect at
comp lete, turn off the ign ition key and rep lace Mercedes-Benz USA on November to,
the contro l unit. Turn the key back on, select the 2008. This policy has specific
F2 key to upload the software and you are requirements for the ordering and
almost done. You shou ld go into "Qu ick Tests" delivery of Theft-Relevant Parts
and scan, then clear, all codes in eac h contro l (TRPs), which may require you to get
unit. Road test the ve hicle and verify that all information from the vehicle owner to
functions are wo rking properly. place an order for certain spare parts.
In the case of the ME contro l un it, make sure In addition, for certain theft-relevant
fu ncti ons such as cruise contro l are working. parts, such as electronic keys,
If coded successfu lly, you shou ld have no prob- electronic ignition switches, infrared
lems and/or wa rning lights on in the dash . This and other locking control units, it is
is now a co mpl eted repair and you can give the mandatory for the dealer to install
veh icle back to the customer with th e confidence them. Please contact your local dealer
that comes from knowing the job was done for a copy of the policy so you can be
right. This shou ld give everyone invo lve d better prepared to help them protect
peace of mind . all Mercedes-Benz vehicles from theft.
24 StarTuned

25. A Mercedes-Benz should be true to its origins. So tum to the Mercellles.B~
Center for Genuine Mercedes-Benz Classic Parts. TheIr experts have
40,000 true-fittin g Genuine Classic Parts of the highest quality, plus a 12-month
limited warranty. They sell dIrect, shIp direct and even assist In parts specification.
Merc edes-Benz Classic Center When you want authentic parts, only the source will do. MBUSA.com/Cla88icCenter
To speak with our Parts Experts, call our Parts Order Desk at 1-866-MB-CLASSIC (1-866-622-5277).
Mercedes-Benz Classic Center USA, 9 Whatney, Irvine, CA 92618
CaU or visit for additional details and a copy of tile limited Parts Warranty. © 2008 Me rcedes~8 e nz USA . lLC

26. FEATURE ARTCLE I COLUSION REPAIR
Taking Stock in Bonds
(Chemical Bonds, that is)
Ease of manufacture, shear strength and aesthetic body lines are only
some of the reasons Mercedes-Benz uses chemical bonding for joining
body panels. How can we duplicate an OEM panel seam?
Take a moment to stand still in New construction, new application of chemical bonding is the
th is day and age and you'll notice and new materials are all used in reduction of vibration and noise
th e incredible changes taking an effort to make vehicles lighter, between mated panels, even
place in many aspects of our lives. stronger and safer for their occu- those that are riveted or bolted.
Continue to stand still and you will pants . When such a vehicle is The techno logy of chemical bond-
become obso lete. We need to involved in an accident, the crum- ing has expanded within the past
keep up with the technology just to ple zones and shear points the few years, so there are many dif-
break even . engineers created come into play. ferent types of adhesives used in
The automotive body repair The result is a passenger cabin the collision repair industry. Each
industry has seen tremendous with minimal intrusion and distor- type has its own characteristics
changes over the past five years. tion, and, hopefully, an outer body that are more suited to some jobs
that's repairable . Traditionally, than to others. You need to know
metal panels were joined using these details if you are going to
various welding techniques that offer factory-like construction in
depended on the application. Inner your repair. If the vehicle's struc-
structural panels were welded tural integrity depends upon
together and outer panels and chemical bond ing, you need to
other body components were maintain this construction integri-
mechanically fastened , either by ty in a collision repair.
riveting or bolting.
Different Types
Glue 'em Together? of Adhesives
A kit is available through your
With modern vehicle construc- As mentioned earlier, there are
Mercedes-Benz parts supplier tion, there are places that are too many different types of bonding
that will allow you to bond difficult to get to (or " blind," adhesives for use in the automotive
panels using adhesives. meaning access is impossible) to body repair industry. In the past,
Notice the two static mixers use mechanical fasteners or spot cyanoacrylate (or, "Krazy Glue")
with pink tips. Before attach- welders. Also, different kinds of was used for minor repairs to tail
ing the mixing tube, squeeze materials need to be attached, so light assemblies and mouldings. It
out one inch of material. After welding is no longer an option . dries very fast, even faster with a
attaching the tube, squeeze Chemical bonding adhesives may drying agent or adhesion promoter.
out another inch to equalize work well in situations like these . The mechanical characteristics of
Another often-overlooked benefit this glue are generally not suited for
the amounts.
26 Stal-Tuned

28. COLLISION REPAIR / CHEMICAL BONDING
automotive applications, however. see an adhesive compound mi xed
It is a very thin liquid and doesn't with a hardener similar to that
fill gaps satisfactorily. As a result used with body filler. This chemica l
of being thin, it doesn't work well reaction usually occurs best at 75
with porous materials, either, but it deg. F. and will take about an hour
can be used in low-stress minor or somewhat more to dry. It will
repairs on metal or plastic just take roughly four hours to fully
make sure you have a tight fit with cure, but you can continue repa irs
minimal air gaps. after the first hour. Acrylics may
Next, there are bonding glues. dry faster, but their strength limita-
These are usually epoxy-type tions should limit them to smaller
adhesives, but can also be com- repairs.
posed of acrylic or methacrylate Urethane adhesives are also
compounds. These adhesives are useful in automotive applications.
strong and well suited for automo- While not as strong as epoxy bond-
tive applications . They apply as a ing glues, it can be used for larger
gel/heavy liquid so they tend to plastic repairs found on bumpers,
stay where they are applied . Being brackets and/or backing panels. It
thicker, they fill surface irregulari- can also be used for gri lle, head-
First, squeeze one inch of ties fairly well when bonding pan- lamp assemblies, moulding and
bonding material out of the els. They are not as temperamen- emblems. It is thicker than cyano-
tal as some other adhesives, but acrylate, so it fills gaps well and
tube, then install the static
there are some conditions we stays where it is applied . It does
mixer and discharge another
need to know to get the best per- have a very short working time of
inch to "equalize" the
formance out of them. The num- under a minute, so be prepared to
mixture. This will ensure ber-one thing to understand is that fit components together quickly. It
equal and properly mixed these bonding adhesives dry by is a two-part adhesive that needs
adhesive material. chemical reaction. You will usually to be mixed before application .
The Application
Process
As in any collision repair, sur-
face preparation is often the most
time-consuming step. It is always
a good idea to remove as many
layers of coating as possib le so
the adhesive can bond to the
The two-part adhesive plastic
housing fits into this applica-
tor gun. The gun is necessary
if you're going to use the new
applicator kit. Its small size
makes it ideal for smaller
patch panel and full panel
bonding.
28 StarTuned

29. Enticingly graceful and dynamic.
Strong support, too.
QUALITY FIT PERFORMANCE VALUE SERVICE
WARRANTY
Every part comes with the reassurance
oj' a strong !2-month/ LlIllimited-mifeage
limited warranty - with additiona! lJJverage
for engines and transmissions:
Unlike any other.
The part is just part of the story. The precise fit and superior performance of a Genuine Mercedes-Benz
Part is a given . But equally important is that each Genuine Mercedes-Benz Part - down to the last nut,
bolt and gasket - comes with the unmatched technical support and expertise from your dealer and
Mercedes-Benz. All evidence of our constant dedication to supporting your business in more and better
ways than anyone else. And that's the best part. Visit mbwholesaleparts.com or contact your dealer. Mercedes-Benz
·See !"ur A/err:etJesBenz deater forderaits and a copy of lhe Merr:etJes·IJellz Ileplacemelll Parts Limilerl Warmnly.

30. COLLISION REPAIR I CHEMICAL BONDING
alignment with other body panels.
Do not pull up on the panel to
reposition it. Instead, slide the
panel into its proper position.
Clamping
During this time body repair pan-
els should be clamped together to
hold them in the proper position,
force the adhesive into surface
irregularities, and squeeze out
excess adhesive. Many automotive
bonding agents contain glass
bead, which provides a heavier
consistency. Once again, this
helps fill gaps and maximizes the
surface area of the bond, which
leads to more strength. This is a
Mercedes-Benz requires all chemical bonding to be supported by result of a material's "bond line
some mechanical attachment such as spot welding. Or, when control," which is its ability to
attaching dissimilar metals, you can use these special structural ma intain thickness under clamp-
rivets, which are available from your Mercedes-Benz parts supplier. ing forces. Use as many clamps as
you can fit and make sure they
mechanically strongest surface. Iy a plastic tube with groves that hold the panels tight. At this point
Diffe rent bond agents are avail- direct the adhesive mixture togeth- take a clean rag or acid brush to
able for metal and plastic attach- er for proper consistency. Before remove any excess adhesive mate-
ment. Follow the instructions of installing the static mixer, "equal- rial before it dries. Of course, once
the adhesive manufacturer ize" the mix by forcing about one it dries it will be a lot harder to
regard ing bonding surfaces prepa- inch out of the tube. Then, install remove. If you can, schedule your
ration. In any event, you will need the static mixer and again squeeze work so you can let t he bonding
a clean surface to begin. Start off out a small amount of adhesive. material cure overn ight. As men-
by cleaning with soap and water. This starts off the mixing process tioned earlier, you can heat the
Follow up with an astringent used correctly. Depending on the appli- area to reduce the curing time if
in pl astic prep. Thi s provides an cation, apply a bead about 10 to necessary.
oil-free surface that will not con- 13mm wide at the panel contact Once the adhesive is fully cured,
tam inate adhesive chemicals. points . While the chemical reac- you can continue with your repair.
Sandpaper of 180 grit will provide tion is occurring, you'll notice that With a proper bond, you have
an optimal surface for the adhe- heat is being generated. This is returned the structu ral integrity of
sive to bond to. It is very impor- normal. Remember how long the the vehicle as close as possible to
tant that all the loose material working time of your adhesive is . its pre-collision state. Proper
from sanding be removed before Since the reaction is temperature repairs not only affect crash wor-
app li cation. Thoroughly clean the sensitive, you can control it to thiness in future accidents, but
surface once again with prep some extent by heating or cooling also the resale value of your cus-
cleaner to prepare for the adhe- the area. Heating will speed up the tomer's Mercedes-Benz, although
sive appl ication . drying process. You can use a heat these points are often overlooked .
If an epoxy requires a two-part lamp and bring the area up to Your peace of mind comes from
mix, don 't just "eye" it. Use a glue about 140 deg. F. Apply the panel knowing you performed the best
gun with a static mixer. It is mere- to the vehicle and make sure of its job you could.
30 StarTuned

31. STARTUNED
GENUINE MERCEDES-BENZ PARTS ... NEARBY
Belmont Palo Alto Walnut Creek
Alabama Park Avenue Motors Mercedes-Benz of Walnut Creek
Autobahn Motors
650-637-2333 650-494-031 1 925-937-1655
Dothan
Mike Schmitz Automotive Beverly Hills Pasadena West Covina
334-794-6716 Mercedes-Benz of Beverly Hills Rusnak/ Arcadia Mercedes-Benz of West Covina
310-659-2980 626-795-8004 626-859-1200
Hoover
Crown Automobile Buena Park Pleasanton
House of Imports Mercedes-Benz of Pleasanton Colorado
205-985-42 00
714-562-1100 925-463-2525
Colorado Springs
Huntsville Calabasas Riverside Mercedes-Benz of Colorado Springs
Mercedes-Benz of Huntsville Mercedes-Benz of Calabasas Walter's Auto Sales & Service, Inc. 719-575-7950
256-837-5752 818-591-2377 951-688-3332
Denver
Carlsbad Rocklin Murray Motor Imports
Mobile Von Housen's Motors
McConnell Automotive Hoehn Motors 303-759-3400
760-438-4454 916-630-8877
251-476-4141
Chico Sacramento Littleton
Montgomery Courtesy Motors Auto Center Mercedes-Benz of Sacramento Mercedes-Benz of Littleton
Jack Ingram Motors 530-893-1300 916-92 4-8000 303-738-7700
334-277-5700
EI Dorado Hills San Diego Westminster
Mercedes-Benz of Eldorado Hills Mercedes-Benz of San Diego Mercedes-Benz of Westminster
Tuscaloosa 916-567-5100 858-279-7202
Leigh Automotive 303-410-7800
205-556-111 1 Encino San Francisco
Mercedes-Benz of Encino Mercedes-Benz of San Franc isco Connecticut
Alaska 818-788-0234 415-673-2000
San Jose Danbury
Anchorage Escondido
Beshoff Motorcars Mercedes-Benz of Danbury
Mercedes-Benz of Anchorage Mercedes-Benz of Escond ido
408-239-2300 203-778-6333
907-277-3383 760-745-5000
Fairbanks Fremont San Jose Fairfield
Auto Service Company Fletcher Jones Motor Ca rs Smythe European Mercedes-Benz of Fairfield
907-456-6217 510-623-11 11 408-983-5200 203-368-6725
Arizona Fresno San Luis Obispo Greenwich
Mercedes-Benz of Fresno Kimbal l Motor Mercedes-Benz of Greenwich
Chandler 559-438-0300 805-543-5752 203-869-2850
Mercedes-Benz of Chandler San Rafael
480-403-3400 Glendale Hartford
Calstar Motors R.A.B. Motors
L 15-454-0582
New Country Motor Cars
Phoenix 818-246-1800 860-278-2000
Phoenix Motor Santa Barbara
602-264-4791 Laguna Niguel
Mercedes-Benz of Laguna Niguel Santa Barbara Auto Group New London
949-347-3700 805-682-2000 Carriage House of New London
Phoenix
860-447-3361
Schumacher European Santa Clarita
480-991-115 5 La Jolla
Heinz Gietz Autohaus Mercedes-Benz of Valencia North Haven
Tucson 858-454-7137 661-753-5555 Mercedes-Benz of North Haven
Mercedes-Benz of Tucson 203-239-1313
Los Angeles Santa Monica
520-886-1311 W.I. Simonson
Downtown L.A . Motors Delaware
213-748-8951 310-526-4700
Arkansas Santa Rosa Milford
Manhattan Beach
Fayetteville Carwell Smothers European I.G. Burton
Mercedes-Benz of Northwest Arkansas 310-303-3500 707-542-4810 302-424-3042
479-521-7281 Modesto Signal Hill Wilmington
Modesto European Mercedes-Benz of Long Beach Mercedes-Benz of Wilmington
Little Rock 209-522-8100
Riverside Motors 562-988-8300 302-995-2211
501-666-9457 Monterey Stockton
Mercedes-Benz of Monterey Berberian European Motors Florida
California 831-375-2456 209-944-5511
Clearwater
Anaheim Newport Beach Thousand Oaks Lokey Motor
Mercedes-Benz of Anaheim Fletcher Jones Motor Cars Silver Star A.G. 727-530-1661
714-777-1900 949-718-3000 805-371-5400
Oakland Coral Gables
Arcadia Torrance
Mercedes-Benz of Oakland Mercedes-Benz of Coral Gables
Rusnak/ Arcad ia Mercedes-Benz of South Bay
510-832-6030 305-445-8593
626-447-111 7 310-534-3333
Bakersfield Palm Springs Van Nuys Cutler Bay
Mercedes-Benz of Bakersfield Mercedes-Benz of Pa lm Springs Keyes European Mercedes-Benz of Cutler Bay
661-836-3737 760-328-6525 818-461-3900 305-251 -0345
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