I just purchased a 1993 dodge cummins turbo diesel. Its an extended cab automatic dually. When I was driving it home the transmission felt like it was trying to downshift between fifty and sixty miles an hour. I was wondering if anyone might know what the possible problem could be? It seems to shift smoothly through all of the gears and will drive at seventy fine. I was going to change the transmission fluid and filter as soon as I can. Any help would be appreciated!

 

Sounds like the Throttle Position Sensor (TPS) is worn (common). Check "The Sticky" (at the top of the 1st Gen forum) for how-tos describing adjustment, replacement, etc.

 

New to the site can anybody help me with my truck a93 cummins won't shift after 40 mph it is a auto and the tranny fluid looks good thanks for your time

 

Probably also a bad tps.

 

You really need to start a new thread as this one is over a year old.

 

Thanks for your help I will try that

 

Truck is junk. You are looking at major repairs. I will help you out and buy it back for 70 cents on the dollar.

 

I need a new tranny is what u r saying

 

No, heck no. I am sorry I was fooling. You probably have a bad or out of adjustment TPS. It is a relatively simple and easy fix. Go check out the stickey http://www.pdrdiesel.com/oldsite/Tech1GTPS.htm

The truck is most likely shifting in and out of Over Drive because the throttle position sensor is misreading the voltage, it has a very little tolerance. Mine happened to get fixed when I put electrical contact jelly on the connections on the engine and on the trans. Once again I am sorry.

 

No big deal about foolin around I checked the voltage like u said made some adj but with a wot in reads at about 3.4 then if I back it off to a 2.75 with a wot my low end is .38 my tv cable looks good does this mean my tps is bad thanks for all your help u r great

 

The at rest should be .6-1.2 VDC. "The total increase (above "at rest voltage") should range between 2.25 and 2.75 VDC." You adjust the voltage by turning the bolt underneath the plastic in or out. If the TPS is bad, you may consider the POT modification. But once again, I chased this problem for years and it was finally bad connections and dirty terminals. Get your voltage set and move on from there.

 

This may be no help but, I had a fusable link go bad (the main one that feeds the inst cluster) and I ran a jumper to get me home but the wire was a little loose. For a couple of miles, the wire would lose it's connection, speedo would fall to zero, and OD would kick off. When the speedo came back on, so did the OD.

Like I said, probably no help but you never know.

 

Mine did the same thing... I just replaced the TPS with a POT from radio shack. I bet if you clean and adjust your TPS it will help....

Trust me..1st thing to check... bad Battery, loose cables or a loose wire to the voltage regulator.

Weak overall Voltage can cause this same issue. And is very likely whats up with your truck..

 

I have not checked the voltage reg yet great idea thanks I will be putting on the pot today I hope that wrks I sure appreciate your ideas

 

I may be wrong but I thought the voltage was controlled by the computer I did not think their was a regulator can u set me strait on that and if their is a regulator were would I locate it my truck is a 93 auto thanks again