GM Service techs 5th gen Camaro Active handling issue

[TTA]

My 2011 Camaro has been in the shop the better part of the month trying to track down an ABS active handling issue that causes the car to go into reduced power mode.
I've dumped close to $4000 into it and it's still not fixed.
The local place I generally take my cars passed it off to the dealer and throwing parts at it hasn't resulted to much but now the dealer is starting to point fingers at my aftermarket radio.
I can get more info from my son as to what they've replaced so far but they've done injectors, a tune-up, modules, and a complete brake job. The problem still appears sometimes immediately sometimes after a few minutes of driving.
They keep saying there's a communications failure.
I'm at a loss and my son is just sick of dealing with it.
He picked the car back up today for the 3rd time and made it almost all the way home before the lights came back on, the past two times it came on before he left the dealers lot.

[mustangmike6996]

That sounds like a nightmare. What faults/DTCs is it setting?

If possible, remove or turn off power to the aftermarket radio. It could be crashing a CAN bus and taking out other modules.

When the issue presents itself,does a key cycle resolve the issue?

[WhiteHawk]

I have seen something like this before. One of the modules on the car is messed up. I saw it on a Corvette that has something crazy like 19 modules. They found a bad resistor in the parking brake module and it was screwing up the CAN bus. Not sure how the guy even found it. The guy who found it was the regional service tech specialist down in Miami. I will reach out to him and see what he says.

-Geoff

[WhiteHawk]

I just IMed him. He said the dealer should be able to locate the fault using the "DataBus Tool" - that is a GM proprietary software.
He said if they are using that, and it is showing the radio as the fault, then that is most likely the cause. I would call the dealer and verify how they are checking it though.

-Geoff

[RSpencer]

Sounds like a high speed CAN issue. The factory radio would be on the low speed bus so unless there’s some seriously botched wiring or interference being picked up on HS from the radio like Mike said.

[RSpencer]

Can the dealership duplicate the issue? Do you have anything plugged into the OBD2 port?

[TTA]

ok, let me find out the exact faults and ask the dealer what they're using to test it.
I've offered them the OEM radio to put back in but they sounded like they didn't want to do that.
I was going to call Cartoons to set up an appointment for that. I believe this radio was all plug and play, it kept all the controls and OnStar. I don't think there was any hacking of the harness but I could be wrong.

[TTA]

oh, Something I pointed out to them is the Radio has been in the car over 5 years, this is a new issue but they said the wires could have corroded.

I'm not sure if the Dealer duplicated the issue but we've given it to them 3 times while the lights were on and they've been able to scan it while it was erroring. A key cycle removes the error but it comes back at random times, sometimes quickly, sometimes it'll take half a day.
Nothing is plugged into the OBD2 port.

[mustangmike6996]

I'd take it to a different GM dealer. They don't sound like they're doing any root cause diag, just minimal troubleshooting theory and hit you with the "parts cannon". Them not wanting to install the OE head unit and complete diag then following up with "might be a corroded wire" sums that up. Like posted above,they should see which module (s) are offline/comm loss. A missing termination resistor will cause the fault all of the time.

I'm thinking it might be a failing wheel speed sensor causing the PCM to close the throttle body.

[WhiteHawk]

I'd take it to a different GM dealer. They don't sound like they're doing any root cause diag, just minimal troubleshooting theory and hit you with the "parts cannon". Them not wanting to install the OE head unit and complete diag then following up with "might be a corroded wire" sums that up. Like posted above,they should see which module (s) are offline/comm loss. A missing termination resistor will cause the fault all of the time.

I'm thinking it might be a failing wheel speed sensor causing the PCM to close the throttle body.

I was thinking that too, but I don't see how it would crash the CAN bus. The old GM's were notorious for having to replace the hubs on the trucks because of that sensor fault. Not sure if the new ones require and all new hub or not.

-Geoff