Throttle Position Sensor: Description and Operation

Throttle Position Sensor (TPS):

Throttle Body Assembly - Exploded View:

Throttle Position Sensor Circuit Diagram:

DESCRIPTION
be Throttle Position (TP) sensor is a potentiometer connected to the throttle shaft on the throttle body. It is a potentiometer with one end connected to 5 volts from the ECM and the other to ECM ground. A third wire is connected to the ECM to measure the voltage from the TP sensor.

OPERATION
As the throttle valve angle is changed (accelerator pedal moved), the voltage output of the TP sensor also changes. At a closed throttle position, the voltage output of the TP sensor is low (approximately 0.5 volt). As the throttle valve opens, the output increases so that, at Wide Open Throttle (WOT), the output voltage should be approximately 5 volts.

By monitoring the output voltage from the TP sensor, the ECM can determine fuel delivery based on throttle valve angle (driver demand). A broken or loose TP sensor can cause intermittent bursts of fuel from the injectors and cause an unstable idle, because the ECM detects the throttle is moving.

If the TP sensor circuit is open, the ECM will set a DTC 22. If the TP sensor circuit is shorted a DTC 21 will be set. A problem in any of the TP sensor circuits will set either a DTC 21 or 22. Once a DTC is set, the ECM will use a default value for TP sensor, and some vehicle performance will return.