4L80E trans
 

Hi all, new to this forum. I'll help where I can, but right now I have a problem. My 95 K2500 4L80E trans will sometimes not upshift into 3rd. If I power down, start right back up, it will work fine for a couple of days. Changed the filter and fluid, only lasted a month. Anything easily replaced without a teardown? This is my daily driver, with 140K miles.

At 140k you are coming to the end of its "useful" first life....but check all the plugins and wires and look for anything unusual, broken, loose, ect.......also try a complete reset and relearn of the computer...just to see if that helps.

Thanks for the reply. I unplugged all the connectors I could find and did not see any problems. How do I do a relearn? Can I do it with a scan tool?

A relearn cant be done with a standard scan tool.....undo the battery cable for several hours, and then drive it for about 30-45 min....preferably on the highway

I have not had a reoccurance since unplugging all the connectors, but I will also do the relearn. Thanks for the help.

Good....you must of had a lose connection somewhere...glad its fixed