Throttle Position Sensor: Testing and Inspection

A "Scan" tool displays throttle position in volts. Voltage should increase at a steady rate as throttle is moved toward wide open throttle. The Electronic Control Module (ECM) has the ability to auto-zero the Throttle Position Sensor (TPS) voltage. Auto-zero can be described as the ability of the ECM to determine a closed throttle position at anytime the TPS voltage is within a specified range. A failure in the TPS or circuit should set a Code 21 or 22. Refer to System Diagnosis / Diagnostic Charts / Diagnostic Trouble Code Charts.