My buddy has a 96 2500 4X4 and it wont shift into overdrive. I hooked up my scanner and it says the trans temp is 14,663 degrees. What could cause the computer to get a reading that far off?

 

An open circuit to the trans temp sender results in a low reading.
Supply voltage to the sender is 5 volts.
Seems like if you are getting such a high reading that the signal voltage back to the computer is in excess of 5 volts.
I would suspect a short to 12 volts somewhere in the wiring.

Could also be your scanner. Pre '97 trucks use the DBR Chrysler only system, not OBD.
Unless you paid in excess of $2000 for software it could be what's wrong.

 

The scanner is a snap on scanner when it was new it was in excess of 2000. It reads everything else ok just the trans temp is way too high. That high reading would also keep it out of od but not sure where it even reads trans temp. I dont see a sensor like my first gen has.

 

On a '96 the sensor is internal, you have to drop the pan to get at it.

 

ok thanks for the help