I remember a post awile back about transmissions shifting erratic in the cold temps. I think it was suggested to change the temperature sensor. Where is it located? It was also suggested to check the TPS. Throttle response has always been good through full range. I don't think it is a problem.
Overdrive keeps shifting in and out even after the engine is fully warm. Doesn't stop acting up until after 85km's/55mph. Any suggestions or tips? What exactly am I looking for?

 

The trans temp thermal switch is located in the trans line on the drivers side of the truck. Where the trans cooler line exits the treanmission.

I would also check the TPS voltages. TPS is there only to let the SBEC(computer) know where the throttle position is. The TPS has no impact on how the engine runs. If your throttle position is too high ( too high of a TPS voltage), it will kick out the overdrive function. I'm almost sure that the speed sensor and throttle position combined are used to govern OD engagement/disengagment.

OD is also disabled if the coolant temp is too high (thermal switch under intake manifold on drivers side) or the trans temp is too high.

I recently had a problem with no OD at all. I has corrected itself, but I believe it was a ground issue. All sensors tested ok

Den

 

Thanx Den . I'm gonna bet it is the temp sensor because when the warm spring and summer weather arrive.......... it works just fine. I'm gonna look up some more information on it now that I know where to look and I'll let you know.