Standard Emissions

CODE 22 THROTTLE POSITION SENSOR (TPS) CIRCUIT SIGNAL VOLTAGE LOW

Diagnostic Chart:

TP Sensor Circuit:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor has a potentiometer whose resistance changes along with the throttle valve position. The Engine Control Module (ECM) provides a 5.0 volt reference to the TP sensor. The ECM reads the voltage across the sensor and converts it into throttle position. When the sensor resistance decreases, indicating the throttle valve opening is increasing to wide open throttle, the voltage being monitored at the ECM increases. When the sensor resistances increases, indicating the throttle valve opening is decreasing to idle, the voltage being monitored as the ECM decreases.

Diagnostic Trouble Code (DTC) 22 will set if the following condition is met for at least 2 seconds: Low voltage input at the ECM indicated with the engine running off idle.

TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. Measures throttle position sensor signal voltage at sensor. Checks for short to ground in LT GRN/WHT wire.
2. Checks for reference voltage from the ECM.

DIAGNOSTIC AIDS
For TP sensor adjustment procedure, refer to Throttle Position Sensor / Adjustments.

DTC 21 and DTC 22 stored at the same time could be the result of an open LT GRN wire.