Multiple Issues with electronics

DaveHow · Sep 30, 2025

2023 GMC AT4 purchased about 9 months ago. Problems experienced includes: Phantom collision sensor activation 4 or 5x when no vehicles in front of me. Loss of active stop start system for weeks at a time then works again. (personally I'm not a big fan of this but am concerned with what system is failing. Is it connected with any others?) Phone connection lost 4 or 5x. Lane warning indicator non functioning now. Collision distance warning system adjust Non functioning now. Collision warning indicator MIL always on. Recently on a trip the truck would not turn off. Finally got that working again and a MIL lit up for engine. Pulled codes and received 4 separate Control module indicator codes. Next day. MIL disappeared and the truck functions properly again. Currently at the shop. A little frustrating for a vehicle that only has 20K on the clock.

LegalBrief · Sep 30, 2025

@DaveHow I’m sorry but you bought a used truck, suspect it may have been in wreck before you got it.

iOS 26 has issues, update to 26.1 many issues are sorted.

DaveHow · Sep 30, 2025

LegalBrief said:
@DaveHow I’m sorry but you bought a used truck, suspect it may have been in wreck before you got it.

iOS 26 has issues, update to 26.1 many issues are sorted.

Been through it top to bottom, no accident on record, no signs of damage or repair. It had 11K when I bought it. Hopefully they can sort the issues out. Luckily it's still under warranty.

pinebaron · Oct 1, 2025

Did you try a complete truck reset? Either from the infotainment system or better still, disconnect negative battery terminal/s for at least fifteen minutes or more, then reconnect. Additionally check the state of your batteries, their voltage/s at rest state; GMC truck electronics are sensitive to battery voltage. Lets start with this.

sloopdawg · Oct 1, 2025

might sound kinda' crazy but what about your grounds

DaveHow · Oct 2, 2025

pinebaron said:
Did you try a complete truck reset? Either from the infotainment system or better still, disconnect negative battery terminal/s for at least fifteen minutes or more, then reconnect. Additionally check the state of your batteries, their voltage/s at rest state; GMC truck electronics are sensitive to battery voltage. Lets start with this.

Thanks for your input. I did try the battery reset. Tried the infotainment reset, tried the door open door closed sequence. None worked. Battery is perfect. Updates are current. Finally took it into the dealership. They took two days to repair it. When asked what the did to repair the problems all I got was they have "Special GM equipment" to reset these systems. They also looked at the wiring loom and found no chafing. So I'm at the mercy of the "Special GM tool guy" whenever the electronics fail. In June 26 the warranty runs out. I'll be getting extended coverage that specifically covers the electrical systems in this truck.

DaveHow · Oct 2, 2025

sloopdawg said:
might sound kinda' crazy but what about your grounds

Sloop, done and done. Nothing amiss there.

tahoetruck · Oct 3, 2025

Extended Warranty is your only defense against a nightmare dealer bill in the future. I have a '23 AT4 and had issues with the lane detection system, a week at the dealer, multiple reprogramming and replacement of the front camera (behind the mirror). Finally fixed but the de-bug charges back to GM Warranty must have been outrageous. Read up on the lemon laws. FYI; 80kmile extension to my current warranty = $4,200. from dealer.

DaveHow · Oct 7, 2025

tahoetruck said:
Extended Warranty is your only defense against a nightmare dealer bill in the future. I have a '23 AT4 and had issues with the lane detection system, a week at the dealer, multiple reprogramming and replacement of the front camera (behind the mirror). Finally fixed but the de-bug charges back to GM Warranty must have been outrageous. Read up on the lemon laws. FYI; 80kmile extension to my current warranty = $4,200. from dealer.

Thanks for the information. Have you used the extended warranty or was your repair under original warranty. A quick review of the Platinum coverage included some notable exclusions in the "Electrical department". Soooo, I'm most interested in the electrical as the mechanical seems to be fairly straight forward. Some have max repair limitations on the electrical side and pixel count (fading camera?).