I had a rebuilt auto tranny put into my truck and since then the tranny will not stay in od. I have read and read and replaced the TPS/CPS or ESS, the VSS, and the trany temp sender. Note the truck will stay in od for a short time while still cold but after 5 minutes on the highway it shifts from 4 to 3. I have adjusted the TPS to no avail in spec and out it just will not stay in od and the cruise will not work. Is there something that I missed or do I have to replace the ECM? When placed on a scan tool there were no codes in the computer. Any help would be appreciated. Thanks

 

I dont know if this helps but I am only getting 500 rpm out of the cps and 1900 at wot. This is a brand new mopar cummins part. I think that idle should be 750 and 3000 at wot. I am getting 8.8 volts at the cps. Any help would be appreciated.

 

pretty sure the OD/cruise failure is an ECM issue.. do a quick search in the dodge firest gen section. i'm pretty sure it's been covered there a few times.

could be as simple as a ground.

 

I have cleaned and added extra grounds to rule that out so its probably the ecm that is bad. Does anybody know if the ecm manages the power to the cps and what voltage should be there? Cant figure why I only get 500 rpm at idle and 1900 at wot unless the ecm controls the cps. I read some where that the cps generats its own power?

 

Depending on how long ago or how may miles since you "had a rebuilt auto tranny put into" your truck, I'd be looking at one of two possible options: 1) Get the shop that did the work to fix it, or 2) Install a POT and wire it up manually to bypass the ECM. #2 appears to be a good, common solution to this problem. Most report it works better than stock that way anyhow, from what I've heard. That might be what Bud is referring to.

 

So the saga continues. yesterday I wired in a ground switch to the od solenoid and tadah I have overdrive. I found that my cps was reading acurately and I am 99% sure now that the ecm is the culprit. Still no cruise, at least i have manual od till I buy a new computer. A lesson for anyone else that runs into this issue, if you need to save a buck run a ground switch to the orange with green stripe wire on the od solenoid. The blue wire is 12v keyed do not tap that wire.

 

A potentiometer (POT) allows it to bypass the ECM with an adjustable shift point behaving more or less like stock - no manual switching required.