P0123

DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage






Circuit Description

The throttle position (TP) sensor is a potentiometer. The control module supplies the TP sensor a reference voltage, a 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 in order to determine the throttle blade 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) the first time the diagnostic runs and fails.
- 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/Failure Records.

Conditions for Clearing the MIL or 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. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
- Use a scan tool in order to clear the DTCs.

Diagnostic Aids

The scan tool reads the throttle position in volts. The scan tool should read about 0.45 to 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).

The scan tool will read the throttle angle percentage. 0 percent at closed throttle. 100 percent at 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 below the 1.25 volts (1250 mV) when the throttle was closed to over 4.5 volts (4500 mV) when the throttle is held at WOT position.

This DTC will result if the TP ground circuit is open or the TP signal circuit is shorted to voltage.

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.