4l80 problems

[joe hatfield]

recently changed motors out in my 93 GMC. everything was fine untill yesterday. the trans started refusing to shift into OD. 1,2,3 shifts are fine, but it will not shift into OD it remains in 3rd. we changed the fluid when we replaced the motor. it feels like i am getting tc lockup in 3rd, but refuses to shift into OD. we cleaned most of the sensors before installing the motor will clean the rest this weekend and see what happens. any thoughts would be welcomed

[GMC Hauler]

I had a loose connection on the temperature sensor that is on top of the coolant crossover. It caused a similar condition that kicked the transmission out of overdrive while driving. Give that a check.....

[cruzer]

Sounds like your throttle position sensor is out of adjustment. It's the black thing on the pass side of the pump w/wires. You need to do a seach on how to or maybe someone else will chime in. You will need a multimeter to do the adjustment and it is very easy to do. I had the same symptoms when I rebuilt the engine and replaced the pump. Hope this helps.

[Eduardo]

You may want to check this thread.

http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=1;t=008441

Good luck.