Throttle Position Sensor: Description and Operation

THROTTLE POSITION SENSOR - PCM INPUT

Throttle Position Sensor And Idle Air Control Motor:

The throttle position sensor mounts to the side of the throttle body.

The Throttle Position Sensor (TPS) connects to the throttle blade shaft. The TPS is a variable resistor that provides the PCM with an input signal (voltage). The signal represents throttle blade position. As the position of the throttle blade changes, the resistance of the TPS changes.

The PCM supplies approximately 5 volts DC to the TPS. The TPS output voltage (input signal to the powertrain control module) represents throttle blade position. The TPS output voltage to the PCM varies from approximately 0.35 to 1.03 volts at minimum throttle opening (idle) to a maximum of 3.1 to 4.0 volts at wide open throttle.

Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. The PCM also adjusts fuel injector pulse width and ignition timing based on these inputs.

When the TPS indicates a voltage that is too high, too low or not believable, the PCM sets a DTC. When the DTC is set, the MIL is illuminated and the PCM moves into limp-in mode. Limp-in for the TPS is divided into three categories:
- Idle
- Part-throttle
- Wide open throttle (WOT)