Table 1 shows one common electrical system related problems of the 2021 GMC Sierra 3500.
| Problem Category | Number of Problems |
|---|---|
| Electrical System problems |
The contact owns a 2021 GMC Sierra 3500. The contact stated that while his wife had the vehicle idling with the rear defroster activated, shortly afterwards, she observed smoke coming from the plastic on the rear sliding window. After a visual inspection, the contact's wife observed that the plastic was melting, prompting her to deactivate the rear defroster. No warning lights were illuminated. The vehicle was taken to the dealer, who was unable to determine the cause of the failure. The vehicle was not repaired. The manufacturer was not notified of the failure. The failure mileage was 26,000.
When carrying the electronic key in my pocket the vehicle will lock/unlock presumably due to the remote contacting other items in the pocket. I have owned well over a dozen gm vehicles and never had this issue. I believe the remote design has the lock/unlock buttons too proud of the surrounding surface.
Multiple instances of diesel engine emissions system parts and software failure. While driving, towing or not, the dic would randomly display a message that the def level is low and reduced speed will occur in x-amount of miles and that mileage would then begin a visible countdown on the dic, sometimes much more quickly than the actual speed I was traveling. In other words, it might at first state 500 miles remaining, but then be counting down from 500 miles by one mile per second of time, or faster. Each instance, I would park and attempt to refill the def tank, only to discover that the tank is already full or near full. My truck’s def tank has now been replaced twice under warranty with the latest tank being installed at only 35,460 miles on the odometer. During the latest replacement, the technician also diagnosed and replaced the electrical wiring harness related to the def tank, stating that one of the connector pins was not reading the required voltage. There was also a faulty diesel particulate sensor that was replaced under warranty. This emissions system is problematic, and it is unsafe to due to the drive ability restrictions it imposes due to faulty software and equipment. I use my truck to tow, and it would make for a very unsafe condition to have my vehicle’s speed become limited as if the vehicle ran out of fuel. Mountain grades. Two-lane highways. Passing through bad neighborhoods. Driving in uninhabited areas, sometimes late at night. Family of 6 in the vehicle. Unacceptable. General motors corp. Must create a permanent and fail-safe fix for this emissions system and implement the parts. The emissions system warranty should be extended from 80k miles to lifetime to cover the vehicles affected.
Trailer brake wiring connection continually disconnectsthen reconnects some time later. Some periods of up to 10 minutes without having trailer braking power. Major safety issue when toeing fifth wheel trailer. We lost brakes going down steep grades. GMC is aware of issue, but has not provided a solution. Vehicle has been yo service shop with no resolution. Case has been opened with GMC.