Can a defective TPS cause an erratic shift?
 

My daughters 01 L200 started shifting erratically at about the same time the check engine light indicated a problem with the TPS. The trans does not slip, it just shifts hard, and shifts at the wrong time sometimes. Thanks, Howie

Well ..... it could. The Throttle Position Sensor (TPS) is one of a number of signals that is sent to the Powertrain Control Module (PCM), which sends shift signals to the transmission and will ultimately affect the overall driveability of the vehicle.

Sorry, I almost forgot to resolve this issue. The tps was the problem. New tps= happy ending.

excellent -- good good good in the area