Mercedes Collision Prevention Assist Inoperative

Michael Mobile Technician Clinton, Utah Posted   Latest  
Case Study
Electrical
2014 Mercedes-Benz CLA45 AMG 2.0L 7-spd
C0811 — ISO/SAE Reserved

I was asked to look at a Mercedes this past week that had the collision warning lights on the dash and in mirrors on. From the Quick Test, I received several codes pointing to CAN messages not being transmitted from the front collision avoidance module A90. C081100, C05D100, C05E100, C333400. The module is buried behind the bumper. I found that it was not accessible from underneath. In the visual inspection I found a suspect connector that appeared to feed the module. It was behind the inner fender. I was able to unhook wire from the body and bring through the inner fender. In testing I confirmed HI and LO CAN signals, power and ground on one side of the connector. I was missing power on the other side. Below are pictures of the connectors. At first I could see the potential of a bad connection due to corrosion. In further inspection, I could see that one of the pins was corroded to the point it was shorter than the other pins. Since connectors are hard to get for Mercedes, the shop owner opted to splice the wires directly bypassing the connector. The system was back up and running and he delivered the vehicle. 

diag​.​net/file/f74bf2t3w…

diag​.​net/file/f35ku6xpl…

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Interesting
Allan Owner
Sterling, Virginia
Allan Default
   

Was the car owner consulted about that? Did anybody sign that they were approving a non standard repair of a major safety system and agree to take the liability off your hands? You’re responsible for the car owners safety. If the shop won’t do It you need to. IMO it doesn’t matter whether anybody thinks it better or worse than before. It’s a collision avoidance system, it’s niw different that…

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Allan: It sounds like you are implying this is an unapproved repair. If so: rts​.​i-car​.​com/collision-repa… HTH, Guido

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Randall Technician
Kunkletown, Pennsylvania
Randall Default
 

Anthony, Thank you for providing the excellent I-car link. It is appears as though we need to be diligent about research on a case by case basis. liability matters Randy

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Randy: You're absolutely correct. Roland Bell says something along these lines: "What I knew to be true yesterday was true. What I know to be true today is true. It doesn't mean that they will be true again tomorrow." Mike's post jumped out at me. I wanted to see if something changed that I wasn't aware of. It did. As materials, procedures, FMEA results, etc. change, what was once…

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Allan Owner
Sterling, Virginia
Allan Default
   

I get that. I’m aware of that site. It doesnt say you can do away with a connector and this isn’t the restraint system. I stick with my opinion, and I am often wrong, that if this car is involved in a collision and a body shop sees that there is a fraction of a chance a greedy lawyer comes looking for some $. it is irrelevant if this will in no way affect the operation of the system. Lawyers…

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Anthony Technical Support Specialist
Kirkwood, Pennsylvania
Anthony Default
 

Hi Allan: It says that the SRS wire harness pigtail is replaced with solder connections. Doing away with it is exactly what they are stating. Nowhere in that blurb is the term "restraint system used". Copy & Paste: Per the Mercedes-Benz service information: "The SRS wire harness pigtail is replaced using solder connectors. Contact a Mercedes-Benz part dealer." I do understand the…

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Allan Instructor
Winnipeg, Manitoba
Allan Default
 

It‘s all about interpretation, what I see when I read the statement “ the SRS wire harness pigtail is replaced using solder connectors“ is, the Supplement Restraint System wire harness pigtail, the pigtail in the wire harness, is replaced using solder connectors. The solder connectors are used to replace the pigtail not eliminate the pigtail. Contact a Mercedes-Benz part dealer - for the part…

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Agree
Michael Mobile Technician
Clinton, Utah
Michael Default
 

Just to make sure we are all on the same page, this was not part of the SRS system but a passive collision avoidance system. Not to say the same care should not be used, but the wires were not Orange or Yellow and the connectors do not have shorting bars or built in resistance.

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Guido, Nice find for future reference. It seems once I saw a TSB for one of the manufactures that stated in the EU repairs were not allowed but were in North America. I wish I could find it now.

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Allan, I only identified the issue. My customer who is the shop did the repair. The vehicle owner is a used car dealer. In this case my hands are clean. I did not tell the shop how to fix it, only what was broke. The whole reason for the post is to demonstrate the need for visual wiring inspections and testing of electrical connections. It would have been an easy mistake to just blame the…

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Allan Owner
Sterling, Virginia
Allan Default
 

I apologize for the misunderstanding. Good job finding the problem. Unfortunately I am a socially awkward ball busting pessimist.

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Funny
Edwin Mobile Technician
Charleston, South Carolina
Edwin Default
 

Allan...i didn't realize that we belong to the same club.....😁

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Allan Owner
Sterling, Virginia
Allan Default
 

😂 the older I get the worse I am

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