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Posted

I have a fleet of gm's that I work on ( I work in an open pit mine), I have recently found that a no start with these and no comm to ecm or tcm goes back to ccm. Every one that I've had the issue with, when inspected closely, shows signs of metal deterioration on the back of the chassis control module. When backing plate is removed, everyone has been full of water and the circuit board is generally covered in corrosion. Buy a new module, plug it in and no start is gone as well as the codes. I've gotten to the point that every new module I buy, I run a bead of rtv silicone along outside seam of backing plate

  • 4 years later...
Posted
On 2/26/2020 at 1:55 PM, Timmer66 said:

This may or may not be related as there are so many ways a system can fail but the comment about a failure to communicate with the chassis control module is/was part of my issue.  I've had a serious problem lately with my 2016 Silverado dying on me but it usually throws up a bunch errors starting with Service Trailer Brake and Stabilitrac Off,  before going into limp along mode and then eventually just packing it in, though the engine continues to run but the tack drops to zero.  Once I shut it off it will not re-start however at one point when it wouldn't start I disconnected the EBCM (ABS) and it started. I reconnected it and it wouldn't start (suggesting the issue was the EBCM or the CCM or the wiring in between).  There is also a clear correlation between this happening and wet sloppy Ontario roads. Twice I've had it towed to a dealer and what they've found is a slew of communication errors between all of the devices on the main GMLAN which includes the ECM, TCM, TCCM, Telematics module, HMI module, Body Control Module, PSCM, EBCM and finally the Chassis Control Module. Unfortunately however by the time they've taken it into the shop, it runs and there are no active faults. Two dealers spent a combined 14 hours pulling apart wiring harnesses starting where they go through the door sill all the way to the chassis control module and found nothing. They said it's almost always a small nick in the wire with signs of corrosion around it. Eventually I got tired of paying big bucks for someone to unwrap wires so I took it home and started pulling it apart myself and checking the wires inch by inch very carefully. Eventually in a section just in front of the left rear wheel I found what is almost certainly the culprit, exactly as described. The nick was in an area that neither dealer had touched I suspect because it's such a pain to get at. In my case the wire wrapping had loosened up and the wrappings had filled with mud and salty water but I suspect subsequently drained out upon sitting allowing the communications to resume. Appreciate that the network operates between 1 and 3 volts so pulling it down doesn't take much. As of this morning I have it all back together and no fault codes. Fingers crossed that I've fixed it. It's just started snowing so tomorrow will be a good day for a test drive.

 

LAN Schematic.jpg

IMG_2463.JPG

IMG_2412.JPG

 

On 2/26/2020 at 1:55 PM, Timmer66 said:

This may or may not be related as there are so many ways a system can fail but the comment about a failure to communicate with the chassis control module is/was part of my issue.  I've had a serious problem lately with my 2016 Silverado dying on me but it usually throws up a bunch errors starting with Service Trailer Brake and Stabilitrac Off,  before going into limp along mode and then eventually just packing it in, though the engine continues to run but the tack drops to zero.  Once I shut it off it will not re-start however at one point when it wouldn't start I disconnected the EBCM (ABS) and it started. I reconnected it and it wouldn't start (suggesting the issue was the EBCM or the CCM or the wiring in between).  There is also a clear correlation between this happening and wet sloppy Ontario roads. Twice I've had it towed to a dealer and what they've found is a slew of communication errors between all of the devices on the main GMLAN which includes the ECM, TCM, TCCM, Telematics module, HMI module, Body Control Module, PSCM, EBCM and finally the Chassis Control Module. Unfortunately however by the time they've taken it into the shop, it runs and there are no active faults. Two dealers spent a combined 14 hours pulling apart wiring harnesses starting where they go through the door sill all the way to the chassis control module and found nothing. They said it's almost always a small nick in the wire with signs of corrosion around it. Eventually I got tired of paying big bucks for someone to unwrap wires so I took it home and started pulling it apart myself and checking the wires inch by inch very carefully. Eventually in a section just in front of the left rear wheel I found what is almost certainly the culprit, exactly as described. The nick was in an area that neither dealer had touched I suspect because it's such a pain to get at. In my case the wire wrapping had loosened up and the wrappings had filled with mud and salty water but I suspect subsequently drained out upon sitting allowing the communications to resume. Appreciate that the network operates between 1 and 3 volts so pulling it down doesn't take much. As of this morning I have it all back together and no fault codes. Fingers crossed that I've fixed it. It's just started snowing so tomorrow will be a good day for a test drive.

 

LAN Schematic.jpg

IMG_2463.JPG

IMG_2412.JPG


So were you able to fix it, and if so what did you do? Did you just cut the wire where the break is and throw a butt splice in there and tape it up? I am having this same issue so please let me know.

Posted

1. 4 year old thread

2. 5 year old post you quoted

3. timmer hasn't logged onto the site in more than 2 years

4. do you even know if you have the same wiring problem that timmer had

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