P0123

DTC P0123

Circuit Description

The throttle position (TP) sensor is used by the powertrain control module PCM in order to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer sensor with a 5-volt reference circuit, a low reference circuit, and a signal circuit. Rotation of the TP sensor from the closed throttle position to the wide open throttle (WOT) position provides the PCM with a signa voltage from below 1 volt to more than 4 volts through the TP sensor signal circuit. If the PCM detects an excessively high signal voltage, this DTC will set.


DTC Descriptors

This diagnostic procedure supports the following DTC. DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage


Conditions for Running The DTC

The ignition is ON.


Conditions for Setting The DTC

- The TP sensor signal voltage is more than 4.8 volts.

- The condition exists for 10 seconds.


Action Taken When the DTC Sets

- The control module illuminates the malfunction indicator lamp (MIL L) on the second consecutive ignition cycle that the diagnostic runs and fails.

- The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

- The control module turns OFF the malfunction indicator lamp (MIL L) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

- Clear the MIL and the DTC with a scan tool.


Diagnostic Aids

- The PCM 5-volt reference circuits are Internally connected within the PCM. If all the TP sensor circuits are OK, inspect the MAP sensor for malfunctions.

- If the DTC occurs intermittently, performing the DTC P1121 diagnostic test may isolate the cause of the fault. Refer to DTC P1121.P1121

- For an intermittent condition, refer to Intermittent Conditions.Symptom Related Diagnostic Procedures


Test Description

DTC P0123 Steps 1-11:

DTC P0123 Steps 12-15:

The number below refers to the step number on the diagnostic table.

2. This step verifies that a condition exists

4. This step tests the signal circuit for a short to voltage. If scan tool displays a voltage after the TP sensor is disconnected, the circuit is shorted to a voltage.

5. This step isolates the condition. Test the. 5 volt reference circuit for a short to voltage if the measured voltage is more than the specified value.

6. This step isolates the condition. Test the low reference circuit for an open or high resistance if the measured voltage is less than the specified value.