My overdrive is cutting in and out, checked the trans with a test switch and the OD works fine. Charging system and speedo work properly, didnt find any obviously damaged wires, trans temp switch checked out OK.
(not CPS equipped)
Cleaned the engine wiring harness connectors and no change.

Is there a coolant temp switch for the computer that could cause this?
Could be the PCM?

If I can't get it to work normally then I guess that I'll have to try the
pressure switch on the trans port to control OD

Any ideas?

 

Anytime I've had a overdrive issue, it's been the TPS. Once I eliminated that $500 sensor with $10 worth of parts from Radioshack, I've never had an issue since.

You don't have a Crank position sensor, or a TPS ?

 

the truck does not have a factory installed CPS, and I forgot to mention
I have elimanated the TPS and done the potentiometer mod, worked
well until recently.

 

Read the last post in this thread.


https://www.dieseltruckresource.com/...65#post3233365


May or may not be relevant.

 

On my truck, I had an intermittent wiring issue I could never find. The TPS was perfectly fine and working. Just intermittent to the OD solenoid. I finally ended up going to a manual switch.

 

I took the potentiometer out for a look, didnt see anything obvious.
Drove it again and it's working now,
Maybe I have a bad potentiometer or a cold solder joint going on.
Looks like I'm on the right track now.
Thanks Cougar