Hello everyone...about a year and half ago I changed the TPS. That fixed the tranny from going in and out of OD. Now the tranny is going in, and out again. I checked the TPS and it is fine. What gives? Is it the PCM? If it is...where is it located? Any other suggestions are welcome.

Thanks, Tony

 

The probability of a bad PCM are extremelly remote.
TPS. Vehcile speed sensor, engine temperature, governor pressure, OD off switch, manifold vacuum, and throttle pressure are main inputs for OD. Wiring is a big possibility at this point.

 

The classic sign of a dying PCM is the WTS light and the heater grids coming on for no apparent reason while you are driving.

Read this thread for a better understanding of how the OD system works.

https://www.dieseltruckresource.com/...ghlight=switch

 

Hmmm...thanks for the imput...now where to start.

1. I've checked and replaced the TPS.
2. Vehicle speed sensor was recently replaced....I will recheck this item
3. engine temperature....according to the gauge the temp is all right. One thing I have noticed is it seems to do it more once I have been driving a while...any ideas?
4. gov, OD off switch, manifold vacuum, and throttle pressure....I haven't a clue.

anyone care to offer some help?

Thanks, Tony

 

[QUOTE=wannadiesel;2179853]The classic sign of a dying PCM is the WTS light and the heater grids coming on for no apparent reason while you are driving.

Read this thread for a better understanding of how the OD system works.

https://www.dieseltruckresource.com/...ghlight=switch[/QUOTE

Will do.

Thanks, Tony

 

One thing I forgot to mention....it came to me after "wanna" posted a link to read. The over drive will stop jumping in, and out if I manually take it out of OD with the OD button. This may narrow down the search.

Thanks guys....I'll keep you posted, Tony