P0122
DTC P0122 TP Sensor Circuit Low Voltage
Circuit Description
The PCM supplies a 5.0. The DTC reference signal and a ground to the sensor. The TP sensor sends a voltage signal back to the PCM relative to the throttle plate opening. The voltage will vary from approximately 0.35. The DTC at closed throttle, to over 4.65. The DTC at wide open throttle.
Conditions For Running The DTC
The engine is running.
Conditions for Setting the DTC
The TP sensor reads less than 0.20 V for 6.25 seconds.
Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) illuminates after two consecutive ignition cycles with the malfunction present.
- The PCM records the operating conditions at the time the diagnostic fails. This information will be stored in The Freeze Frame and Failure Records buffers stores this information.
- A history DTC is stored.
- The TP angle will default to 0% when the vehicle speed is less than 2 mph. The TP angle defaults to 10% when the vehicle speed is greater than 2 mph The scan tool shows the defaulted value
Conditions for Clearing the MIL/DTC
- The MIL will turn off after 3 consecutive ignition cycles in which the diagnostic runs without a fault
- A history DTC will clear after 40 consecutive warm up cycles without a fault
- A scan tool can clear the DTCs
Diagnostic Aids
If a DTC P0122 cannot be duplicated, the information included in the Freeze Frame data can be useful. Use the scan tool DTC information data in order to determine the status of the DTC. If the DTC occurs intermittently, use the DTC P0105 Diagnostic table in order to help isolate the problem.
Steps 1 - 4:
Steps 5 - 7:
Steps 8 - 11:
Steps 12 - 13:
Test Description
The number(s) below refer(s) to the step number(s) on the Diagnostic Table.
1. The Powertrain OBD System Check prompts you to complete some of the basic checks and to store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.
2. The TP sensor has an auto zeroing feature. If the voltage reading is between 0.20 Volts and 0.90 Volts, the PCM will automatically assume this as a closed throttle position (0 percent).
4. This simulates a DTC P0123. If the PCM recognizes the high voltage signal, this indicates that the PCM and the wiring are OK.
5. This simulates a high voltage signal which will identify an open in the signal circuit.
6. IMPORTANT: The Powertrain Control Module (PCM) uses a single internal 5.0 volt power supply to supply power to all the engine control components. If one component shorts its 5.0 volt reference circuit to ground or battery voltage, the other 5.0 volt reference circuits will also have a low or high voltage.
If any additional DTCs are set, check the 5.0 Volt reference circuits for a short to ground.
8. If the test light illuminates while probing the TP signal circuit terminal in step 5, then the TP signal circuit is shorted to ground.
11. Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Isuzu Technical Communications System (ITCS) information for PCM programming and the CKP System Variation Learn Procedure for the crankshaft position system variation learn procedure.