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 signal 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.

CONDITIONS FOR RUNNING THE DTC
The ignition is ON.

CONDITIONS FOR SETTING THE DTC
^ The TP sensor signal voltage is more than 4.75 volts.
^ The condition is present for 10 seconds.

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 tails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic tails, 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 tail.
^ 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. Intermittent Conditions

TEST DESCRIPTION

Steps 1-3:

Steps 4-14:

The number below refers to the step number on the diagnostic table.
10. An internally shorted EGR valve could cause a high voltage condition on the 5-volt reference circuit.