P0122

DTC P0122 TP Sensor Circuit Low Voltage





Circuit Description
The PCM supplies a 5.0 V 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 Vat closed throttle, to over 4.65 V at wide open throttle.
Conditions For Setting The DTC
- The TP sensor reads less than 0.20V for 6.25 seconds.
- The engine is running.

Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) illuminates.
- 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
Whenever this DTC cannot be duplicated, use the information included in the Freeze Frame data in order to evaluate the conditions when the DTC set. A faulty A/C sensor could set a DTC P0122. Disconnect the A/C electrical connector. If the TP reading returns to normal, replace the A/C Refrigerant Sensor.

Test Description








Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool 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 closed throttle position (0%).
4. Simulates a DTC P0123. If the PCM recognizes the high voltage signal, then the PCM and wiring are OK.
5. This simulates a high voltage signal which will identify an open in the signal circuit.
6. If 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, then the TP signal circuit is shorted to ground.
11. Replacement PCMs must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Isuzu Technical Communication System (ITCS) information for programming procedures and also refer to the CKP System Variation Learn Procedure.