Throttle Position Sensor: Testing and Inspection

THROTTLE POSITION SENSOR DIAGNOSIS
A Tech 1 scan tool displays throttle position in volts. The scan tool should display 0.20 volts to 0.90 volts with the throttle closed (idle) and ignition "ON." Voltage should increase at a steady rate as the throttle opens. Voltage should be near 5.0 volts at Wide Open Throttle
(WOT).

The Powertrain Control Module (PCM) has the ability to auto-zero the Throttle Position (TP) sensor voltage if it is below about 0.90 volt (900 mV). This means that any voltage less than 0.90 volt will be determined by the PCM to be 0% throttle. Scan tools also have the ability to display the throttle angle and should display 0% when the throttle is closed, and increase smoothly to 100% at WOT. A failure in the TP sensor circuit should set a Diagnostic Trouble Code (DTC) 21 or 22.