Hey guys,
I hate having to dig up an old thread but I'm having similar issues now with my truck. I have a 2011 Silverado 1500 z71 4x4, the truck has just over 72k miles and last week I started having similar problems with the truck. So what's happening with mine is, while driving the ABS, TC, and brake lights will illuminate on the dash, and then I'll see the service traction control and service stabilitrak messages. It will also say traction control and stabilitrak off. Some times the brake light will go out, while the other 2 are still lit, and then it might come back on a few seconds later. I'm not having door locks going crazy, and the truck still drives and starts. The only other thing I've noticed when driving is that the speedometer needle will kind of flicker up and down while accelerating, but the needle only drops like 5 mph then it quickly goes back to where it actually should be. It doesn't fluctuate all the time, it's completely random.
Anyway, I started searching the internet for info to see if I could find a fix or cause for this. Surprisingly, I could hardly find anything..I swung by an auto parts store the other day when the lights came on and had codes read. I got U0073, U0100, and one or two more U codes...can't remember what they all were. Today, I decided to start looking at control modules and inspect electrical harnessing. I grabbed my meter and had my wife ohm pins 6 & 14 at the OBD2 port while I did wire wiggles. I checked the ECM, BCM, ABS module, and TCM. I looked at wheel speed sensors (abs sensors) and they were fine. When I ohm'd the harness, my base resistance was ~61ohms. Nothing jumped, the meter read the same at every connector until I got to the TCM. I checked it last cause I suspected this was the cause after I read thru this thread last night. Sure enough, as soon as I grabbed the harness, my wife said she say the meter spike to over 100 and then drop as low as 35 ohms, but it never stabilized until I stopped the wiggles. The connector is tight on the trans case, but the wires are dirty (obviously) and feel loose in the connector. I'm thinking this is what's probably causing the "short" which is causing the communication loss to CAN BUS "A". I did a little more searching tonight after messing with the truck and found out that I can't even disconnect the electrical connector, because the locking tab in under the pan. The TCM is bolted to the valve body with 6 bolts, but again I'd have to drop the pan and remove the filter to get to it all. It doesn't seem like it's hard to do, I've just never messed with transmissions so it's something new to me. I don't have the money to take it to a dealership, so idk what I should do. I'm not even sure this is the fix either. I mean, this just started happening and I'm pretty sure that connector has been the way it is for a while. I was thinking I could remove the connector and just clean it out real good and wrap some new electrical tape around the exposed wires to hopefully tighten them up better on the connector, but after researching my plans are out of the question now. I can get a new TCM from rock auto for $99 plus shipping. If I go this route to replace it I might as well replace the trans filter, it's never been replaced and then I'd be able to remove/clean the connector and hope to tighten up/seat the loose wires. At the same time, maybe I'll try to get some extra cash and just take the truck in for service. I guess I'm just looking for advice or a little encouragement. I'd like to know what you would do if you were in my shoes. I'd like to know if anyone else has had these same problems and what they did to get it fixed. I'm gonna talk to my boss tomorrow once I get to work, cause he has a Silverado like mine, (think his is either a 2010 or 2012 CC) and I'll ask him if he's had these problems before on his truck. I guess this is a common thing and GM knows about it, but never did a recall. Imagine that, they didn't even honor my trans dipstick tube recall, mine was never done and I found it broken last year. I called a local dealer and they were like yeah, we can do it but it's gonna cost ya. We don't honor that recall anymore because it's been over 2 years. Man I was pissed, I ordered a replacement with the foam noodle already installed on it from rock auto for $17 and just replaced it myself. I have an air bag recall due on my truck now also, maybe I'll take it in for the recall and see if they can scan it and give me an estimate for the repair cost. I know it's only a $100 part, but they will probably fuck me with labor charges. Seems like it wouldn't take more than an hour to replace it. Anyway, I'm rambling now so yeah, seriously though. If you have already went down this road and have info for a fix or advice/experience please share, thanks.
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