I have a 99 GMC Safari Van ( 2WD) with the 4L60E Transmission. It started getting stuck in first gear and the RPM would go way up before it would shift inot second. Once it made it to second there was no problem unless I slowed down or stopped the car then the whole sticking process started again. Sometimes if I have driven it for a while it will do slip until it cools down again. Anyway I had a friend of mine who does this type of work on the side rebuild the Transmission and replace the Valve Body (Installed a new solonoid kit also). He put everything back together and it's still slipping and the same code of Soloniod A is bad is still there same as before.

Anybody have any Ideas of what is going on or what else needs to be changed to fix this problem.

 

Can you get the actual number for the code rather than the definition it might be helpfull

 

souns like there is problem in the servo possibly.

 

the code I am getting is P0751 and P0753. What is a servo and how do I check to see if that is the problem?

 

If you are sure the valve body and solenoids are good. The check the external wiring for the transmission to the PCM. Wires can break inside the insulation or even short to ground.