P0122

DTC P0122

Circuit Description

The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5-volt reference circuit, a common low reference circuit, and 2 independent signal circuits.

The TP sensors have opposite functionality. TP sensor 1 signal voltage increases from below 1 volt at idle to above 4 volts at wide open throttle (WOT). TP sensor 2 signal voltage decreases from above 4 volts at idle to below 1 volt at WOT.

If the ECM detects TP sensor 1 signal voltage is too low, this DTC sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0122 Throttle Position (TP) Sensor 1 Circuit Low Voltage

Conditions for Running the DTC

* The ignition is ON, with the engine OFF, or the engine is operating.
* The ignition 1 voltage is more than 7 volts.
* DTC P0122 runs continuously once the above conditions are met.

Conditions for Setting the DTC

The ECM detects the TP sensor 1 signal voltage is less than 0.18 volts for more than 4 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 4 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

* Use the J 35616 Connector Test Adapter Kit for any test that requires probing the ECM harness connector or a component harness connector.
* The lower connector of the ECM is connector C1 and the upper connector of the ECM is connector C2. Refer to Engine Controls Component Views.
* If there is a condition with the TP sensors, the ECM defaults to reduced power mode for the entire ignition cycle, even if the condition is corrected.
* For an intermittent condition, refer to Intermittent Conditions. Intermittent Conditions

Test Description

Step 1 - Step 6:

Step 7 - Step 14:

The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that a condition exists.
4. The TP sensors share a 5-volt reference circuit. If both DTCs P0122 and P0222 set, test for a condition in the 5-volt reference circuit.
5. The ECM produces a measurable steady-state amperage that provides the 5-volt reference to the TP sensors. If the amperage on the 5-volt reference circuit is less than 50 mA, test the 5-volt reference circuit for an open or a high resistance.
6. This step tests the signal 1 circuit of the TP sensor. If the TP sensor 1 voltage parameter is not 4.8-5.2 volts, test for a condition in the signal 1 circuit.