Hi All,
Warning: Long read below. For summary, jump to bottom of post!
For my first post here, I'd like to get some input on what I might be dealing with. I got my 08 Trailblazer LT (4.2) about a year ago, and ever since I've been dealing with the TCC intermittently locking/unlocking over and over, along with some other shifting issues. The TCC locking/unlocking happens at cruising speed and it is very intermittent. It may go days without happening but when it does it locks/unlocks over and over for no apparent reason. It also seems to occasionally try to lock up while I am still accelerating, much sooner than anticipated, and this often triggers the lock/unlock condition, but that is also very intermittent.
After reading about this TCC issue in numerous threads, I ordered the transgo shiftkit and went to install it, only to find that the previous owner had already done so. While inside the transmission, we noticed that the PO also had the 1-2 accumulator piston replaced/modified, and there was still debris inside the bore and that accumulator was stuck
We also looked at the separator plate and everything looked fine with no noticeably worn holes. Nevertheless, we installed the new stuff from the shift kit and got the accumulator freed up and got it back together. The 1-2 shift was much better (go figure), but the TCC issue was still occurring.
Since we saw that the transmission had been modified, the trailblazer has over 130k on the odo and I plan on keeping the vehicle for a while, we decided to buy a remanufactured transmission directly from GM thinking this would solve all of the transmission problems, which it unfortunately did not... Most of the shifts feel much better, but there is still a bad hitch between shifts, usually accompanied by a clunk sound/feeling which I believed the famed "torque management" system, but it sure send clunky and not enjoyable to drive. The big problem is that the TCC is still unlocking/locking at cruising speeds, and I've just started getting (4-5 times in the past couple weeks) a real hard 1-2 shift, which almost feels like I'm being rear-ended.
We've since installed a new brake switch and a new accelerator pedal both directly from GM, along with new spark plugs just in case. There are NO codes being set, and I'm totally at a loss for where to start with this thing... I'm hoping someone might have some input of things I can check before I keep throwing money at this problem. I appreciate any input in advance!
Summary of above:
Main issues:
1. TCC sporadic locking/unlocking at constant speed
2. Sometimes tries to shift into 3rd way too early
3. Overall clunky/slow shifting
3. No codes to indicate any problem
Attempted fixes:
1. Remanufactured transmission direct from GM
2. New accelerator pedal from GM
3. New spark plugs
[Mod edit: Please do not post successively. Posts merged and edited.]
Warning: Long read below. For summary, jump to bottom of post!
For my first post here, I'd like to get some input on what I might be dealing with. I got my 08 Trailblazer LT (4.2) about a year ago, and ever since I've been dealing with the TCC intermittently locking/unlocking over and over, along with some other shifting issues. The TCC locking/unlocking happens at cruising speed and it is very intermittent. It may go days without happening but when it does it locks/unlocks over and over for no apparent reason. It also seems to occasionally try to lock up while I am still accelerating, much sooner than anticipated, and this often triggers the lock/unlock condition, but that is also very intermittent.
After reading about this TCC issue in numerous threads, I ordered the transgo shiftkit and went to install it, only to find that the previous owner had already done so. While inside the transmission, we noticed that the PO also had the 1-2 accumulator piston replaced/modified, and there was still debris inside the bore and that accumulator was stuck
Since we saw that the transmission had been modified, the trailblazer has over 130k on the odo and I plan on keeping the vehicle for a while, we decided to buy a remanufactured transmission directly from GM thinking this would solve all of the transmission problems, which it unfortunately did not... Most of the shifts feel much better, but there is still a bad hitch between shifts, usually accompanied by a clunk sound/feeling which I believed the famed "torque management" system, but it sure send clunky and not enjoyable to drive. The big problem is that the TCC is still unlocking/locking at cruising speeds, and I've just started getting (4-5 times in the past couple weeks) a real hard 1-2 shift, which almost feels like I'm being rear-ended.
We've since installed a new brake switch and a new accelerator pedal both directly from GM, along with new spark plugs just in case. There are NO codes being set, and I'm totally at a loss for where to start with this thing... I'm hoping someone might have some input of things I can check before I keep throwing money at this problem. I appreciate any input in advance!
Summary of above:
Main issues:
1. TCC sporadic locking/unlocking at constant speed
2. Sometimes tries to shift into 3rd way too early
3. Overall clunky/slow shifting
3. No codes to indicate any problem
Attempted fixes:
1. Remanufactured transmission direct from GM
2. New accelerator pedal from GM
3. New spark plugs
[Mod edit: Please do not post successively. Posts merged and edited.]
Last edited by a moderator: