davewbrandt

I just picked up a 91 d250 diesel with intercooler. Trying to troubleshoot overdrive problem. Also speedometer not working. The first thing I found is the tps is missing. Not just the tps but the drive mechanism that turns in when the throttle is operated. There is no crank position sensor. I am not sure if it is supposed to have one as it doesn't have a tach. The tps is expensive but they are available, the drive mechanism I can't seem to find. Any helpful info would be appreciated.

j_martin

Welcome to the board.

Do some searches here. There's tons of information on the TPS, including ways to use a pot, a gasser ($30) TPS, or resistors for a set shift spot.

davewbrandt

I would like the truck to work the way it is ment to. I know where to get a tps and how it works. To be more specific where do I find the rest of the parts to properly install the tps. I did searches and found lots of conflicting info on the crank sensor. I have ordered a manual and hope I can determine if it needs a crank sensor from it. I checked the vss and found it had been replaced. The old one was under the seat.

j_martin

Under the TPS there's a plastic drive piece with a hex screw in the bottom. The head of that screw is driven by a hex hole in the throttle. The parts illustration shows that screw head hanging down, but it must be part of the TPS mounting bracket.

I've replaced mine with a gasser TPS, which takes a different home made drive piece. If I ever clean off my work bench, I probably have a couple laying around.

The TPS circuit on these isn't as dry as it should be. (It runs a little too much current through the wiper of the potentiometer.) They're hard on TPS's, which is why I converted to a cheap TPS.

The speedometer problem may be mechanical internal. There's info on it in the FAQ section here. I can be repaired in the home shop or kitchen table.

u2slow

When I miss-installed the speedo cable in my '90 RC's tcase... the speedo, OD, and cruise were crippled at the same time.