P0123
DTC P0123 TP Sensor Circuit High 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
- DTCs P0107 or P0108 not set.
- Engine is running.
- MAP is less than 60 kPa.
- Engine speed is less than 1500 RPM.
Or
- DTCs P0107 or P0108 not set.
- Engine is running.
- MAP is greater than 60 kPa.
- Engine speed is greater than 1500 RPM.
Conditions for Setting the DTC
- The TP sensor voltage is greater than 3.9 volts for 13.75 seconds when the engine speed is less than 1500 RPM.
Or
- TP sensor voltage is greater than 4.8 volts when the engine speed is greater than 1500 RPM.
Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) illuminates after two consecutive ignition cycles with the malfunctions 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 P0123 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, use the DTC P0105 Diagnostic table in order to help isolate the problem.
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.
Steps 1 - 5:
Steps 6 - 9:
Steps 10 - 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. With the throttle closed, the TP sensor voltage should read less than 0.80 volts. If the TP sensor voltage does not read less than 0.80 volts, check for a binding or a sticking throttle cable.
4. The PCM and the wiring are OK if the TP sensor voltage is less than 0.3 volts with the TP sensor electrical connector disconnected.
5. Probing the ground circuit with a test light checks the circuit for high resistance which will cause a DTC P0123 to set.
7. 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.
A shorted 5.0 volt reference circuit will also set additional DTCs.
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.