Welcome back to our 2015 GMC Canyon long-term test. To read the whole series, click here.
My first real issue with our long-term GMC Canyon has arisen. After four months of driving this truck, the transmission seems to be having some troubles.
The issue first came to light while I was driving home from work. As I accelerated just after taking a sharp right-hand corner, a slow shift made the truck feel like it was hesitating for about two seconds. The transmission answered with uncertainty when I asked for more power; it’s an uncomfortable feeling.
This same sensation happened again several times over the past month. It seemed to only happen right in the middle of the throttle range and never at full tilt. There was no hesitation when I pushed the pedal all the way to the floor, just a hard downshift and a surge of power. But when I asked for just a little more power, the transmission seemed to get confused. Another issue also cropped up during this time: rough, clunky shifts. The tranny would think, then bang down into gear a little harder than felt proper.
“The vehicle has a shift stabilization feature that adjusts the transmission shifting to the current driving conditions in order to reduce rapid upshifts and downshifts. This shift stabilization feature is designed to determine, before making an upshift, if the engine is able to maintain vehicle speed by analyzing things such as vehicle speed, throttle position, and vehicle load.”
After reading this, the behavior started to make more sense, but the next two sentences are the most revealing.
“If the shift stabilization feature determines that a current vehicle speed cannot be maintained, the transmission does not upshift and instead holds the current gear. In some cases, this could appear to be a delayed shift [emphasis added], however the transmission is operating normally.”
This put my mind at ease somewhat, but to be sure there wasn’t a larger issue brewing, I contacted General Motors Canadian Truck Product Manager Craig Couch about my problems. After going for a test drive, Couch assured me that there was nothing wrong. “The shift quality you were perceiving is normal, but the range of experience that the truck had over a short period of time meant that it had not ‘settled’ to its most stable shift points,” he wrote in an e-mail.
It is fair to note that this truck had been in a wide range of driving situations in the four short months we’ve had it. That includes having multiple drivers on a regular basis, plowing through one of the coldest winters in recent memory and frequently towing different size loads. That said, this scenario is certainly not outside the realm of possibility for a typical Canyon owner.
“Shift quality adapts are the largest area of adapting, the most complex,” Couch explained. “Some of these adapts run early in the ‘life’ of a new transmission/vehicle and then periodically over the life of the vehicle. Other adapts have the ability to make adjustments continuously throughout the life, though as the adjustments hone in on the desired result they may become more stable and limit the size of the adjustment they are allowed to make.”
So it turns out that part of what I was feeling are natural transmission growing pains according to GM. These transmissions are constantly learning and with 8,500 miles logged, I guess ours was going through some pre-teen confusion. And it does seem to be growing out of it. In the past 3 – 4 weeks, I haven’t felt a delayed shift and can’t replicate it, even when trying.
Not all is right with the truck though. The rough shifting hasn’t gone anywhere. Occasionally, it still clunks down a gear with a pronounced thud.
Normal or not, this transmission has some weird quirks. The issues may only be occasional, but that leaves an overall feeling of being unrefined.
Discuss this story at our Chevy Colorado Forum