I have recently removed the vacuum pump from my '95 k3500 GMC 4X4. With some other events happening I haven't been able to isolate wheather this started just after the pump removal or tranny line loss of fluid. It now wont shift up to overdrive and lock up for a long time and when it does shift up it sends a SES light. While the light is on the tranny shifts and works properly, but when you shut the engine off and re-start the lihgt goes out and the tranny wont shift again. Is there a need for a jumper to fool the ECM into thinking there is vacuum to the WG. I have a turbo master installed and have been told that the vacuum pump only supplies to the waste gate, but it has an electric connection with the ECM. Does anyone have some insight here?

when you get the ses light on read the codes and let us know what code is in it and mabey we can help

Thanks for the reply. I tried to fine a reader that would read the codes but no luck in my vacinity. I figured out the problem by myself. It turned out to be a broken sensor connector on the water pump crossover. I don't know what the sensor feeds but the temp gauge in the cab was still working. I tried a couple of test runs with it un-plugged and plugged in to see if that was really the problem. With the sensor unplugged the tranny wont shift into OD or lock-up. When you plug the sensor in it works like a champ. Thanks again.