March 2022 I finished my transmission rebuild on a 4L80 where I put the Transgo reprogramming kit, and AFL repair kit in, I used Transmission Bench videos and master rebuild kit. I also installed a Tru-Cool 40K with a thermal bypass as I live in a mountainous area and live full time in a slide in, homemade camper that is on the truck 90% of the time. In the last few weeks, I’m having an intermittent issue where it wont up shift out of second, even on the downhills, and I’m running 3,500 rpms at 55mph and the trans temp goes through the roof then comes back down. Yesterday I drove 100miles not letting it go above 2,000rpms, so slow as **** for any uphill, and for a lot of the drive I was going 60 and it never did the shifting thing but the temp did shoot up to 260° before I pulled over and shut the truck off for 30 min. When I’m going 25-30 up Dallas Divide, 8% grade, the transmission actually cools off a little.
The computer pulled the code P0756 so I replaced the shift solenoids and B fell apart in my hand pulling the plug so I thought I had my issue licked but I did not. I’m looking for ideas to try before I pull the valve body and rework it, again. Any help would be appreciated.
1999 Classic, K3500, crew cab, long bed
The computer pulled the code P0756 so I replaced the shift solenoids and B fell apart in my hand pulling the plug so I thought I had my issue licked but I did not. I’m looking for ideas to try before I pull the valve body and rework it, again. Any help would be appreciated.
1999 Classic, K3500, crew cab, long bed