I have a 2012 Silverado which was running perfectly fine for a while now. Not too long ago the ABS light and traction control lights both came on. After some back and forth with my own inspections and reading forum threads, it led me to replace the EBCM Module.
Where I live, it’s pretty hard to get a hold of new parts so I picked one up from a scrapyard. After installing everything and checking that everything was secure, even though the ABS and traction control lights were still on, the truck was running like normal.
About 1 week after the EBCM module was replaced, however, the truck no longer starts and I’m now getting an engine code U0073. I tried doing my own research on forum threads but there’s just far too much mixed information on this.
I would start with checking the fuses and relays. then…
Inspect the wiring harness. You are looking for chafing, burnt wires, or melted wiring/plastic. Pay particular attention to anywhere that the harness needs to go around a bend or touches anything that could damage it. You are looking for an open/short. If there is damaged wiring, you’re going to need to repair the harness. If there doesn’t seem to be any visible damage to the harness, you’ll need to move on to checking the harness connections at the control modules.
Inspect the harness connections. Once you’ve established that the wiring harness looks fine, the next place to look is where it plugs into your Silverado’s control module(s). Unplug the harness from the control module. Once unplugged, inspect the pins to see if there is any damage to them. If one or more of them look discolored compared to the rest of the harness, that is likely to be what’s causing U0073. You can use electrical contact cleaner to properly clean the harness pins. Check to see if the module can communicate with a scan tool. If it can not the only thing left is one of the modules has likely gone bad.
Your truck has several computers. They must be able to communicate with each other 100% reliably, in all directions, for your truck to ever work correctly. The u0073 indicates that’s not happening. The problem could be the harness connections between the modules, or one or more of the modules are faulty. This sort of problem is best debugged using a pro-level scan tool that is able to test each segment of the computer communication path to and from all the modules. Unless you can spot something visually, like burned or broken wires, your best bet is to find a shop that has the GM pro scan tool and a tech who’s experienced with this sort of problem.
So you have an ABS/TCS light come on. You don’t say WHY they came on, no code, nothing but that leads you to swap the EBCM (the ABS computer…) with a junk part. Was this a communication problem with the EBCM??
Now you have lost CAN communication and the truck won’t start.
Seems like the 2 may be related. I’ll toss out that the EBCM you bought has failed. OR the actual problem has always been a broken CANbus wire to the EBCM and now it has failed completely. Does this sound plausible to you?
Yeah the ABS/TCM lights came out of nowhere, I’m really not sure why. There was no engine light at the same as when those came on. There was a few different things that I saw online to fix it. I did things like check the wheel speed sensors and checking the bearings as some forum posts advised but nothing worked. The EBCM replacement was the last fix I could find. It still didn’t fix the issue so I just gave up trying to repair the truck but a few days after I stopped doing anything to it, the truck stopped running. I haven’t done anything since the first post but I’m gonna try grasping at some straws later today.
I had an experience where the ABS and traction control warning lights would go on, with no obvious issues while driving. It was annoying and after a lot of internet surfing it seemed likely that my battery was simply failing. The car started OK so I was confused, but finally I gave in and bought a new battery. The problem cleared up immediately and never returned.
Now, understand, my experience was with a Toyota product. And maybe it is completely useless to you. Just a thought. But I do support the idea that you should try replacing the EBCM with your old one. Sometimes the cure is worse than the disease.
I can see how that’d be very annoying. It seems hard to believe both of those warning lights could turn on yet there is nothing in any of the car’s modules saying why. It’s possible I suppose the ABS or transmission module, body module, or some other special purpose module might have to be queried, requiring a pro-level scan tool.
Turns out, the EBCM replacement had no effect on the truck not starting. It was just very inconvenient timing but I found out my starter failed at the same time as the U0073 code came up. I still have the code along with the ABS and traction control lights but at least now I can drive it to a shop where they can take a proper look at it and see what’s what.
(I confirmed my starter had failed because I pulled it out, wired it up on my bench and it wouldn’t turn. Replaced it and she starts right up)
Manufactures could provide diagnostics and monitors for the starting system, so at least you would have known the starter had failed. But they don’t, presumably b/c there’s no emissions requirement mandates for the starting system. We’ve had this discussion here before. One downside to providing starter system diagnostic is that the diagnostic hardware and software can be what fails.
The truck was diagnosed properly and the mechanic did find out all of the modules are working correctly. The issue is the wiring harness somewhere. Unfortunately that was my worst.case scenario since I could easily just plug in a new module. Now I’ll have to inspect the wiring all over the vehicle to find what is probably a tiny little kink in 1 of the wires.