I have a 1995 dodge ram 3500 12 valve. recently when the truck is warmed up and shut off and turned back on it loses overdrive, cruise, and tach. local shop says its the crank pos sensor. well 100 bucks later its not fixed. another shop says its my speed sensor or body control mod. well before I put more money in it I don't have id like others advise. the truck is just my work truck it tows a trailer or well did until this. built trans, new single disc converter, fuel plate removed, fuels turned up a bit, timing is bumped up a little, straight pipe, new intake manifold, and open air filter is the only mods. when you start the truck let it warm up u can drive it anywhere its fine pulls great good driving truck. I stop to get fuel and food or stop at a friends place 10 min or a hour later if the truck is warm and I start it theres no tach or anything. please help before I cut my losses and sell the truck. I have to have the truck working I need a truck to tow with every weekend

 

anyone? still nothing been checking wires and cleaning plugs and nothing

 

My boy had a similar problem.I had to change a sensor that was on the driver-side of the tranny it was in about the middle two wire plug with two screw?Is there any codes?I think it was called a speed sensor. If you take it out you can check it with a volt meter.there two on that truck one on the tranny and one on the rear end.you tube on how to check those sensor with a volt meter. Hope this helps

 

only code it has is for a alt it has some gm alt and ford regulator on it. when I lose overdrive and tach and stuff I also lose the check engine light

 

so what the code number?

 

ill have to check after work tonight I just ignore the code everytime I check it its just for the alt

 

You may have some diodes gone bad in the alternator, the more of those that go bad, the more rippled the dc voltage gets. That might be locking up the computer.

 

alt was pulled and tested at autozone and napa both. the speed sensor in the trans is only 34 bucks local I got one on order ima just throw it in and see what happens. I'm thinking most likely the pcm

 

Probably is the pcm then, you might check for corrosion on the connector, seems like I read somewhere Chrysler had a problem with that, at least on the Jeeps, I don't know if the trucks have the same issue.

 

Bmph8er
Did you ever figure this issue out? I'm having similar trouble.