Hard Shift until 150 degrees
Thread Starter
CF Beginner
Joined: Oct 2023
Posts: 5
Likes: 0
Hard Shift until 150 degrees
2001 2500HD 4L80E, 6.0 - After winter a couple of years ago, the transmission started shifting hard (really hard). I figured out that when the trans temp reached 150 and I shut it off for a couple of mins, the shifting would return to normal. Changed fluids, no help. This year I replaced the transmission, but I still have the same issue. Any thoughts?
Thread Starter
CF Beginner
Joined: Oct 2023
Posts: 5
Likes: 0
The torque converter came with the transmission. Not sure the TC is the issue as we had the same issue with both. I'm pretty sure I cleared the adaptions. Key on, depress accelerator for 15 seconds, turn key off, releases accelerator. wait a couple of mins before restarting. Does the 2001 2500HD have a separate TCM. or is it embedded in the PCM?
Super Moderator
Joined: Feb 2017
Posts: 6,207
Likes: 689
I'm asking if the transmission you installed (you or a mechanic?) was a used or re-manufactured unit.
I've never heard of that reset procedure and I wouldn't trust it. I would use a diagnostic tool where I can see it and get confirmation.
I've never heard of that reset procedure and I wouldn't trust it. I would use a diagnostic tool where I can see it and get confirmation.
Super Moderator
Joined: Feb 2017
Posts: 6,207
Likes: 689
Your 4L80 control is performed by the Powertrain Control Module (PCM)
Instructions for transmission replacement:
Instructions for transmission replacement:
Important: It is recommended that transmission adaptive pressure (TAP) information be reset.
Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, The ECM, PCM or TCM will need to relearn TAP values. Transmission performance may be affected as new TAP values are learned.
Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, The ECM, PCM or TCM will need to relearn TAP values. Transmission performance may be affected as new TAP values are learned.
Trending Topics
Thread Starter
CF Beginner
Joined: Oct 2023
Posts: 5
Likes: 0
I will look into to tool to reset the adaptive learning. The only reason I countered the TC being reman or new is that it is the exact same issue, so in my mind it wouldn't matter if it was new or not. Something a little off or different, I can see needing to know. Same with the transmission. I'm pretty sure it something outside of those two items. If you have other information that can sway me, please let me know. I will let you know about the reset with a scan tool. Thank you
