Transmission slips between 2nd and 3rd gear when drving in stop and go traffic under 20-mph. I was able to duplicate this concern for the dealership, but they are unable to fix.
Noticed oil on tranny when I did my own oil change. Took to dealer and was informed the torque converter seal needed to be replaced. 6-8 hour job, and all covered by warranty. Dealer said common to first runs of Terrain and Acadia
Transmission was stuck in 5th gear. Mechanics at the dealership disassembled the transmission and discovered torn 1234 clutch piston seal and scored housing. The piston and housing were replaced.
330 TrueDelta members own (or used to own) a 2000 or newer GMC Terrain. 20 of these members
(6.1%) have reported transmission repairs for their car.
A total of 21 transmission repairs to GMC Terrains--an average of 0.1 per
vehicle--have been reported.