P0123

DTC P0123 TP Sensor Circuit High_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 wilt vary from approximately 0.35 V at closed throttle, to over 4.65 V at wide open throttle.

Conditions for Setting the DTC
- Engine is running.
- The TP sensor voltage is greater than 3.9 V for 13.75 seconds.
- MAP is less than 60 kPa.
- Engine speed is less than 1500 RPM.
- DTCs P0107 or P0108 not set. Or
- TP sensor voltage is greater than 4.8 V.
- DTCs P0107 or P0108 not set.

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
- With the ignition ON and the throttle at closed position, the voltage should read between 0.20 V and 0.90 V and increase steadily to over 4.5 V at wide open throttle.
- Check the connectors for proper mating. Replace as necessary. Repair as necessary.

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. With the throttle closed, the TP sensor voltage should read less than 0.90V. If the TP sensor voltage does not read less than 0.90V check for a binding or sticking throttle cable.
4. With the TP sensor electrical terminal disconnected, the TP sensor voltage should less than 0.2 volts if the PCM and wiring are OK.
5. Probing the ground circuit with a test light checks the circuit for high resistance which will cause a DTC P0123 to set.
7. A shorted 5.0 volt reference circuit will also set additional DTCs.
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.