So I put a potentiometer on my truck as the overdrive shift was erratic. The past few days the truck started doing it again with the potentiometer still on the truck, but the trans will only shift with the pot cranked the whole way down to about .2 volts.

I also had the truck down at the dealer. Of course they told me the pot wouldn't work and I had to have a tps. Also, I did find out two helpful things to track down the problem. 1. All the wiring checked out fine. 2 with the tps hooked up, the computer thought the throttle was at 70% at little to no throttle.

So long story short the trans will only shift at low voltage from tps/pot.

Anyone have ave any ideas what is going on?
Bad pcm?
a different bad sensor?
anything else that might be wrong?


thanks in advance

 

I gave up chasing that gremlin a long time ago. In spite of what the dealer told you, your wiring harness is not "fine". Been there. My only option was to bypass the system and go to a switch. After doing the 47RH conversion, the Compushift controller took over the OD control and everything is back to normal, all most. The transmission is fine, but now my charging circuit is now bad. The harness Ohms out, but doesn't carry the load.

 

Ok, thanks. I’ll crawl under it tonight and double check all the wiring.

Do do you have any clue if there is a way to put a pressure sensor somewhere to make the OD work kind of like the rest of the tranny? A switch would be fine, but when someone else drives it, it probably wouldn’t be that good.


Thanks

 

Does anyone have a diagram of the grounds for either
1. Any of the sensors for OD.
2. The pcm
3. The overdrive unit itself.

cant seem to find it in the stickies

thanks