my cruise control will work when i turn off trac control or in comp mode. i always have mine in comp mode and use my cruise control every morning. mine is a 5 speed, maybe in the auto doesnt work, or maybe something is wrong with mine?? lol

 

It works if you turn trac off manually. But if a fault triggers the warning light it turns it off.

 

Ok easmarkey, I got your answer. First off take it to the dealer. Tell them to look at DOC# 1887771. The X4 connector circuit ar C2 Ignition 1 Voltage pin is backed out of the connector from the factory and barely making contact. It will get worse. Here is what else is not working when this happpens.
The front wipers inop.
Power steering will stop working.
Cruise inop.
Rear view mirror compass inop.
Turbo gauge stops where ever it was when it lost power.
The air compressor inop. Blower still works.
Service ESC on dash.
ABS light on.
Tracion light on.
This circuit feeds the BCM and codes will set. When the dealer looks at it and is scratching his head and calls TAC, their responce will be, good luck. Let us know what you find. This happened to me and it is my car. 6 weeks of playing with it and found it. They need to install a new connector because the original has lost the retaining clip for that terminal.
I tried to post a pic up here but GM wont let me or I dont know how.

 

Thanks Turbotech! Any time I can give the dealer a heads up on a problem that isn't happening when I bring it in is a good thing.

 

No problem. Anytime. Let us know what they find. Heard many issues with the underhood fusebox on other cars.

 

I was at the dealer getting my turbo to IC tube replaced and told them about this issue with the cruise control and ESC warnings, so they plugged in and saw that it did indeed throw a code. The only problem is that they said the code was for a sensor that does not exist on this car?!?! It was for a second steering wheel sensor. Apparently there is only 1. They preformed a "relearn" operation on the steering wheel sensor, updated the software and reset everything. They are puzzled, but said that what they did might cure the problem.... I got my fingers crossed

 

Yeah, when mine started acting up, I coudnt communicate with the power steering module at all. That was the first problem. After several programmings, it still was dumb. A new steering module fixed that. Then the rest of the problems came back often. Good luck. Let us know if it happens again.

 

Ok, I dug up a picture of the wire that powers the BCM. This wire is under the underhood fuse box. This is how I found it.

 

Thanks Turbotech, that helps me find the right area to look.
Now I have another issue, but it may have nothing to do with anything else... The maximum boost I can get is 16psi. I used to get in the low 20's. I mentioned that they updated the software, does anyone know if that would include engine management? Does the new release lower boost? Or, it may have something to do with the replacement of the turbo to IC tube??
When I get some more time I may post a new thread on this, so sorry for the redundancy.

 

I just got back from a trip and it involved a lot of driving.
My cruise would stop working after sitting for a few minutes after a long drive (hot engine). I'd get back on the road, it wouldn't work... wait 5 minutes while driving... worked again. This was repeatable. I'm thinking wiring harness connections here myself. Possible heat related affect causing disconnects. No codes or warnings thrown, just inoperative until several minutes into the drive.

Will try re-seating fuses / harness connections and see where that winds up.