I have a 1999 Dodge 2500 diesel. The transmission was shifting erratically at 40-45 mph. I replace the throttle position sensor, had the chip re-programmed per a TSB all did nothing. I even replaced the lift pump and had the trans serviced. Nothing. The other day the injector pump failed. The Computer actaully failed on the pump with a P1688 code. Nothing mechanical. I replaced the pump and the transmission problem went away. It now shifts very well at all speeds. If you have the same truck and are experiencing erratic shifting and have not replaced the original pump, get a pump.

 

Good info, thanks. Post it in the diesel section too.

 

+1 a lot of people post there problems but no solutions, and really that helps no one but the person posting. This will be very helpful to the DF. Thanks again.

 

I know you had an MPH point where this occurred. I have a similar sounding problem that seems to happen between 3rd and 4th gears in the auto tranny. It hesitates and does not want to shift into 4th. m going to try this solution. What brand pump did you buy?

 

Did you have the computer reprogrammed. Dodge will do it for under $100. I would try that first.