Throttle Position Sensor: Testing and Inspection

TESTING
A Tech 1 scan tool displays throttle position in volts. The scan tool should display between 200 to 900 mv with the throttle closed (as at 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).

AUTO-ZERO
The Powertrain Control Module has the ability to auto-zero the Throttle Position (TP) sensor voltage if it is below about 0.9 volt (900 mv). This means any voltage less than 0.9 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 steadily to 100% at WOT. A fault in the TP sensor circuit should set a Diagnostic Trouble Code (DTC) 21 Throttle Position Sensor (Signal Voltage High) or DTC 22 Throttle Position Sensor (Signal Voltage High). Testing and Inspection