P0122

DTC P0122

CIRCUIT DESCRIPTION




The throttle position (TP) sensor 1 is used to determine the throttle plate angle by the engine control module (ECM) for various engine management systems. The TP sensor is a potentiometer type sensor with the following three circuits:
- A 5-volt reference circuit
- A low reference circuit
- A signal circuit

The ECM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. The TP sensor then provides the ECM with a signal voltage proportional to throttle plate movement. The TP sensor 1 signal voltage at closed throttle is low and increases as the throttle is opened. When the ECM detects the TP sensor 1 voltage is less than 0.195 volts, DTC P0122 sets.

CONDITIONS FOR RUNNING THE DTC
- The battery voltage is more than 8 volts.
- The ignition is ON.

CONDITIONS FOR SETTING THE DTC
The TP sensor 1 voltage is less than 0.18 volt for more than 140 milliseconds.

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 1-8:

Steps 9-17:

The numbers below refer to the step numbers on the diagnostic table.
4. The ECM performs a comparison of the signals from both throttle position sensors during the entire range of operation. If the DTC does not set with the key ON and the accelerator pedal released, actuating the throttle may cause the DTC to set.
6. This step tests for the proper operation of the TP sensor 1 signal circuit. The ECM supplies a pull up voltage of about 4.8 volts on the signal circuit.
7. The 5-volt reference for the TP sensors and the accelerator pedal position (APP) sensor 2 are connected inside the ECM. This step is to determine if the APP sensor is affecting the 5-volt reference circuit of the TP sensors.