P0122

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

Wiring Diagram:

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 plate 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 V at idle to above 4 V at Wide Open

Throttle (WOT). TP sensor 2 signal voltage decreases from above 4 V at idle to below 1 V at WOT.

Conditions for Setting the DTC
- Ignition ON.
- No TP sensor fault exists.
- TPS voltage is less than 0.044 V.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.

Conditions for Clearing the MIL/DTC
- The MIL will turn OFF at the end of a consecutive validation cycle in which the diagnostic runs without a fault.
- A history DTC will clear after 40 warm up cycles without a fault.
- DTC(s) can be cleared by using the scan tool.

Diagnostic Aids
If the DTC P0122 cannot be duplicated, the information included in the Freeze Frame data can be useful. Use the scan tool DTC information data to determine the status of the DTC. If the DTC occurs intermittently, using the DTC P0121 diagnostic table may help isolate the problem.

Test Description
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 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 V, test for a condition in the signal 1 circuit.

Step 1 - 14:

DTC Troubleshooting