P0123

Circuit Description
The Throttle Position (TP) sensor is a potentiometer. The Control Module (PCM/VCM) supplies the TP sensor a reference voltage, signal, and ground circuits. When the throttle is depressed, the TP sensor signal rises to near the reference voltage. When the throttle is released, the TP sensor signal decreases from the reference voltage. The Control Module monitors the TP sensor signal circuit voltage to determine the throttle blade's angle (Or opening). This DTC is designed to detect a TP sensor signal voltage higher than the possible operating range of a normally functioning TP sensor.

Conditions for Running the DTC
The engine is running

Conditions for Setting the DTC
The TP sensor signal voltage is more than 4.7 volts for 1 second or more.

Action Taken When the DTC Sets
^ The Control Module illuminates the Malfunction Indicator Lamp (MIL) if a failure is detected during 2 consecutive key cycles.
^ The Control Module will set the DTC and records the operating conditions at the time the diagnostic fails. The Control Module stores the failure information in the scan tools Freeze Frame and/or the Failure Records.

Conditions for Clearing the MIL/DTC
^ The Control Module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
^ A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22°C (40°F) from the start-up coolant temperature and the Engine Coolant Temperature is more than 70°C (158°F) during the same ignition cycle).
^ Use the scan tool Clear Information function.

Diagnostic Aids
The scan tool reads the throttle position in volts. The scan tool should read between 0.45 and 0.85 volt with the throttle closed and the ignition switch turned ON or at idle. The voltage should increase at a steady rate as the throttle is moved toward the Wide Open Throttle (WOT) position.

The scan tool will read the throttle angle percentage. 0 percent equals closed throttle. 100 percent equals Wide Open Throttle (WOT).

Scan the TP sensor while depressing the accelerator pedal with the engine turned OFF and the ignition turned ON. The display should vary from less than 1.25 volts (1250 mV) with the throttle closed to more than 4.5 volts (4500 mV) when the throttle is held at the WOT position.

This DTC will result if the TP ground circuit is open or the TP sensor signal circuit is shorted to voltage. Refer to Symptoms. Symptom Related Diagnostic Procedures

An intermittent may be caused by any of the following conditions:
^ A poor connection
^ Rubbed through wire insulation
^ A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis.

Test Description
The numbers below refer to the step numbers in the diagnostic table.
2. If the TP signal measures more than 4.8 volts then the condition exists.
3. With the TP sensor disconnected, and if the VCM and the wiring are okay, the TP signal should go below 0.25 volt. This test could set a DTC P0122.