P0123

CIRCUIT DESCRIPTION
The throttle position (TP) sensor is used by the powertrain control module (PCM) to determine the throttle plate angle for various engine management Systems. The TP sensor is a potentiometer type sensor with the following circuits:
^ A 5-volt reference circuit
^ A low reference circuit
^ A signal circuit

The PCM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from the closed TP to the wide open throttle (WOT) position provides the PCM with a signal voltage from less than 1 volt to more than 4 volts through the TP sensor signal circuit. If the PCM detects an excessively high signal voltage, this diagnostic trouble code (DTC) will set.

CONDITIONS FOR RUNNING THE DTC
^ The ignition is ON.
^ DTCs P1635 and P1639 are not set.

CONDITIONS FOR SETTING THE DTC
^ The TP sensor signal voltage is more than 4.9 volts.
^ The above conditions are present for more than 1 second.

ACTION TAKEN WHEN THE DTC SETS
^ The control module illuminates the malfunction indicator lamp (MIL) 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) 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.

TEST DESCRIPTION

Steps 1-4:

Steps 5-15:

The number below refers to the step number on the diagnostic table.
5. This step tests for voltage measuring more than the reference voltage.