Cruise control turns off when Rear window Defrost is turned on

[fastscirocco]

I would go back to place that replaced rear window and report to them what is going on.

I did call them, only person that was there to talk to was the receptionist.
I will report back any new info.

 

[rrosen]

I'll give you a history of my cruise control mysteriously turning off. Probably doesn't apply but ....

Cruise control kept turning itself off. Dealer first said there was a chafed wire by the emergency brake that did it. Fixed the wire but the problem still existed. Dealer had car for almost 3 weeks (maybe longer, it was some time ago). Called in the GM engineers. Eventually they replaced...the radio amplifier!?!?!?!?

Apparently the amp was putting spurious signals on one of the busses (CAN bus maybe?) that caused the cruise control to turn off.

Just a data point for what it's worth.

 

[fastscirocco]

I was getting more issues, cruise would intermittently simply not work, if I kept the window down switch pressed down after it stopped closing it would turn the cruise off. Daughter noticed my passenger's side back up light was intermittently not working. I replaced the GM harness for the lights which fixed the back up lights AND the rest of the symptoms.

 

[fastscirocco]

I'm still having the issue, unfortunately this didn't fix it. It just went a long time without acting up, sorry for the bad news.

 

[petethepug]

If the brake switch fails the cruise control doesn’t work. It can also lock the shifter in Park.

It’s lucky your daughter saw that tail light out. That would be where I would dig in. Remove the LED bulbs until this is remedied. CAN BUS runs off 5v in the system and LED, no matter what’s promised as canbus “safe” is NOT guaranteed. If the dealer had it for 3 weeks and you paid them, take it back without any evidence of you working on it.

Let the dealer use their 2 way scanning equipment to find the bug based on no cruise with defrost and intermittent tail lamp out.