Throttle Position Sensor: Description and Operation

Throttle Position Sensor:

Throttle Position Sensor (TPS):

PURPOSE
As the throttle angle changes (pressing down on accelerator pedal) so does the Throttle Position (TP) sensor voltage output. By monitoring TP voltage output, the computer can determine fuel delivery rate based on throttle valve angle or driver demand.

OPERATION
The TP sensor is a potentiometer with one connection to the computer 5.0 volt reference and the other to ground. A third wire from the computer is used to measure the output voltage from the TP sensor.

DIAGNOSTIC NOTES
The Engine Control Module (ECM) uses the reading at idle for a zero reading, so no adjustment is necessary. A problem with the TP circuit will cause a Diagnostic Trouble Code (DTC) 21 to be set. Once a DTC code is set, the ECM will substitute a default value for the TP sensor reading and some driveablity will return.