P0120

CIRCUIT DESCRIPTION

The Throttle Position (TP) sensor is a potentiometer. The TP sensor is mounted on the side of the throttle body. The TP sensor provides a voltage signal that changes relative to the throttle blade angle. This signal voltage is one of the most important inputs that is used by the ECM. The TP sensor has a 5.0 volt reference, a ground and a signal circuit. The signal circuit is pulled up to 5.0 volts within the ECM. When the ECM senses a signal voltage outside of the normal operating range of the sensor, this DTC will set.

CONDITIONS FOR RUNNING THE DTC

The engine speed is greater than 400 RPM.

CONDITIONS FOR SETTING THE DTC

^ The throttle angle is greater than 96% OR less than 3.9%.

^ The above conditions are met for at least 50 milliseconds

OR

^ While cranking the engine, the above conditions are met for at least 2 seconds.

ACTION TAKEN WHEN THE DTC SETS

^ The ECM illuminates the Malfunction Indicator Lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

^ The ECM informs the Transmission Control Module (TCM) of this condition and the TCM enters the Default Mode. The TCM will also request the ECM to illuminate the MIL and will set DTC P1700.

CONDITIONS FOR CLEARING THE MIL/DTC

^ The ECM turns off the MIL after three consecutive drive trips that the diagnostic runs and does not fail.

^ A History DTC clears after forty consecutive warm-up cycles if no failures report by this diagnostic or any other emission related diagnostic.

^ The ECM battery voltage is interrupted.

^ The scan tool clears the MIL/DTC.

DIAGNOSTIC AIDS

Use the Connector Test Adapter Kit J 35616-A for any test that requires probing the ECM harness connector or a component harness connector. Using this kit will prevent damage to the harness connector terminals.

Check the following conditions:

^ Poor connections at the ECM or at the component. Inspect the harness connectors for the following conditions:

- Backed out terminals

- Improper mating

- Broken locks

- Improperly formed or damaged terminals

- Poor terminal to wire connection. Refer to Overall Vehicle Information / Diagrams / Diagnostic Aids for Checking Terminal Contact procedure.

^ Damaged harness. Inspect the wiring harness for damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may help in order to locate the fault.

If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or the connections, the component may be damaged.

Refer to Symptoms / Intermittents. Testing and Inspection

^ If other DTCs are set that share the same 5.0 volt reference circuit, check the entire circuit up to any other components. Check for any shorts to ground or power. If the DTCs are set that share the same ground circuit, check the point where the circuits ground to the chassis or to the engine block.

TEST DESCRIPTION

The number(s) below refer to the step numbers on the diagnostic table:

5. Make sure that all of the test connections are good in order to prevent an inaccurate sweep test of the sensor. Use the jumper wires with the proper mating terminals for the sensor and the harness connector.