When I took it into the dealership, they did no work on it and sent it right back to me with the commentary, “Performed complete vehicle DTC scan. No codes or service bulletins found. Could not duplicate concern. Vehicle is operating as designed.” At that point, I wasn’t sure if the mechanic had someone else warm up the vehicle and transmission fluid so much that the problem went away, he was just incompetent and didn’t recognize the problem, or he was intentionally ignoring the blatantly obvious problem.
The transmission is slow and lurches the vehicle when the fluids are still cold. There’s an option to display transmission fluid temperature in the gauge cluster, and whenever it’s below ~100°F, the transmission takes longer to shift to different gears. This is particularly noticeable when you’re just starting up the vehicle and making your first stop of the day. If you do not come to a complete stop then wait a few seconds (and instead just slow down and roll through a stop sign), the vehicle will hiccup and lurch when you ease your foot off the brake and begin accelerating again.
Yesterday when I got back from hiking, I was browsing the Internet while recovering and came across a class action lawsuit against General Motors, the manufacturer of the GMC Canyon. I got curious and looked into it, seeing as I am a General Motors customer, and got extremely intrigued when I saw that it was regarding a defect in the 8L90 and 8L45 8-speed automatic transmissions. Apparently, the vehicles affected were:
- Chevrolet Colorado, Chevrolet Silverado, Chevrolet Camaro, Chevrolet Corvette
- GMC Canyon, GMC Sierra, GMC Yukon
- Cadillac ATS, Cadillac CTS, Cadillac CT6, Cadillac Escalade
I got in touch with one of the class action lawyers, and I’m in talks with them right now providing relevant information, so hopefully this ends up doing something for me. Even though the transmission sucks, I still really like the truck, and I’ve already put in a good chunk of money modifying it to my desires, so it’s not like I want to completely bail out and get rid of the truck. Ideally, I just want to avoid a situation where I ding 60,001 miles, my powertrain warranty ends, and my transmission proceeds to immediately implode.
“When a driver accelerates or decelerates, the cars will reportedly hesitate and then shudder, jerk, clunk, or ‘hard shift’ when the automatic transmission switches gears. This may also occur when the vehicles are accelerating in a single gear and not necessarily switching gears.”