Q: What is the Throttle Position Sensor (TPS) and how does it work on Chevrolet Trailblazer?
A: The TPS is a variable potentiometer that is mounted on the end of the throttle shaft in the throttle body. Based on the TPS output voltage, fuel delivery can be decided by the PCM in relation to the throttle valve angle. The Throttle Actuator Control system (TAC) and Accelerator Pedal Position (APP) sensor are what the TPS works with. There are two sensors in one housing which make up the latter. Codes are set when there is a difference between actual position of throttle and position as sensed by TPS. The Throttle Position Sensor must be replaced as part of the throttle body unit.