Timmer66

My Silverado had a very similar issue. Lots of faults, reduced power and eventual death. And also when the weather was wet/snowy and crappy. Then after sitting would miraculously self fix. Turned out to be a corroded network wire just in front of the rear wheel. When it got wet it grounded the network and nothing could communicate. A bit of solder and some heat shrink solved it. To the credit of the dealership I dealt with, they really worked to dissuade me from replacing the EBCM when I thought it was the issue, saying they had yet to see one fail. So I persevered until I fount the nick in the insulation.

Perhaps?

Drove 200 km today on sloppy slushy roads without an issue so optimistic I've got it fixed. Yay!! As for tracing the wire I do know precisely what it is. The white wire and the blue wire beside it are twisted together and make up the primary data network that runs between all of the major control modules of the vehicle, starting at the Engine Control Module and ending at the Chassis Control Module. You can see the wires in the diagram at the beginning of this post. They are identified as 2500 and 2501. As you can see they also pass by the Transmission Module, the Body Module, the HMI module and the ABS module. Any issue with either of these wires and the communication between all those modules is affected. In my case the wire was leaking to ground so all communications were toast. If the wire simply broke, you would probably get communication between the devices on each side of the break but not across the break.

Certainly a plausible explanation for the issue you’re having.

Headed out tomorrow on slushy roads to test the fix but looks like it was a nick in the network data wire just in front of the rear wheel. The wrapping had loosened up allowing muck and salt water into the cable bundle where the issue was. I think is was damaged in manufacturing as there were no other signs of abrasion on the other wires. Fingers crossed but I think this was the culprit.

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.

The saga continues. Drove 300 km without issue. First half was light snow and second half was mostly dry road. Started to snow about the time I parked and when I returned to the truck 3 hours later, it wouldn't start. Left it for another hour and it started. Pulled a huge list of codes but basically communication faults galore. Cleared codes and drove 10 km to overnight accommodation. Headed out in the morning in heavy snow for 300 km return trip. About 15 km out it started faulting and went into limp along mode. Cleared faults and continued. Repeated this a couple more times before it finally died for good. Had it towed to my house about 80 km away. Still wouldn't start then, nor in the morning. After sitting in the warm sun for half a day it started again in the afternoon. I haven't cleared the faults. Its getting towed to the dealer in the morning. Along the way I pulled code reports and looking at them the recurring theme is ABS control module communication faults. Also when it was home and wouldn't start I pulled the connector off the ABS controller and the vehicle would start. Put it back on and it wouldn't. I think I've found the smoking gun but I'll have to wait for the dealer to look at it. It looks like the ABS is bringing down the network.

If the connector isn't the issue then it's probably a wire issue as was your case. Unfortunately the dealer couldn't find a problem with it so the trick is going to be catching it in the act which likely means pulled off the road somewhere in a rain/snow storm. Yippee!! If I can figure out where a couple of the other modules are and if they're accessible I can potentially discern whether the issue is fore or aft of that point and hopefully narrow the search. In the meantime I'm not loving driving a vehicle that could die at any moment.

A couple of weeks ago I drove my 2016 Silverado Crew for about 3 hours in a heavy rain with lots of road salt and temperatures hovering around freezing. At my destination I parked for about an hour and when I returned to start the vehicle it threw up a bunch errors on the dash; trailer brake issue, Stabilitrak issue, power steering issue, blah blah blah, but then it simmered down and drove fine for an hour to my next destination. Long story short, it repeated this over the next couple of stops getting progressively worse as the evening wore on and eventually the engine light came on and it went into limp along mode. At this point I had little choice but to make a run for it and head to my final destination about 60 km down the highway. Unfortunately it totally died about half way there, no dash lights, nothing. I had the vehicle towed to a dealer I had dealt with (late Saturday night) and waited to call them on Monday. Interestingly the truck started again when I tried it but I'd had enough excitement for the day so just left it. Apparently the truck started on Monday morning and after spending 5 hr. looking into it and taking it for a 60 km test run they said though it had 18 pages of error codes they couldn't find anything specifically wrong with it and no longer being under warranty I think they didn't want to run up a huge bill with the risk of having nothing to show for it so they charged me for an hour and a half and sent me on my way. I suspect being in a warm shop dried out whatever was causing the issue. Once home I researched all the codes on the work order and they all turned out to be communication faults on the CAN Bus network; CCM can't communicate with ECM, EBCM can't communicate, TCM can't communicate etc. etc. Figuring this wasn't over I bought a code reader and did some research so I'd be prepared should it happen again and maybe reset the codes. For the next 500 km it ran fine until the day I set out for another 3 hr trip in rain and drizzle and a little over 2 hours into the trip it started barfing up faults again. The engine light came on however it didn't go into limp mode or die. When I got to a safe place I stopped and checked the codes. It was pretty much the same scenario so I cleared the faults and the engine light and carried on completing the final 70 km without incident. At home I parked in the driveway and when I came out 20 minutes later to dig in it wouldn't start at all and the code reader couldn't connect. My prime suspects at this point were the CAN bus and salt laced rain water. My first step was to check pins 5 (signal ground), 6 CAN-Hi and 14 CAN- Lo on the OBDII connector. If all was well, there would be 60 ohms resistance across 6 & 14 and megaohm resistance from them to ground. What I found was no resistance between any of them indicating they were essentially shorted together with the ground. I decided the easiest thing to get at was the chassis control module at the back above the spare tire. I pulled apart the connector and confirmed 120 ohms on pins 26 and 29 which is the back end of the network and no leaks to ground so that was good however the incoming pins 27 and 28 indicated the same states as the ODBII pins. Next I found the Electronic Brake Control module and noticed that whoever had worked on it left about 4 inches of exposed wires into the connector (sloppy) and there was wet road sand visible up inside the back of the connector and on the wires leading into the pins. I took a spray bottle with clean RO water (barely conductive) flushed all the sand and salty water (very conductive) out of the back of the connector. Once it was clean I pulled the connector off, and inside it appeared to be dry though the tech had slathered dielectric grease over the face of it making it difficult to be 100% sure. I then confirmed 120 ohms on the inbound pair of CAN Bus wires and 120 ohms on the outbound wires which when connected together gave the requisite 60 ohms overall. Coincidence? Maybe. I then put the connector back on the EBCM and was able to start the truck. At this point I believe this is my problem spot however because the problem is somewhat self correcting it's possible there is another issue and the timing was coincidental but my confidence is fairly high. I subsequently wrapped the wires and took steps to reduce the ability of water and dirt to get into the back of the connector. I also added a dab of dielectric grease to the CAN wires where they enter the connector from the back. So for now I will carry on and see what happens though I will be keeping my code reader and multi-meter handy when I'm on the road. I've attached the CAN Bus schematic and a couple of before and after pictures of the connector wiring in case someone is interested. Something I noticed when putting it together was that the red retaining tab on the connector had been broken off necessitating the second larger tie wrap in the picture to ensure the connector doesn't come undone. I imagine someone pried the connector open not understanding that the red locking mechanism needed to be pushed back first. Hmm. I'll post an update if this reoccurs. If anyone has any insights I'd be happy to hear them.