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P2125



DTC P2125

DTC DESCRIPTORS

DTC P2120
Accelerator Pedal Position (APP) Sensor 1 Circuit

DTC P2122
Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage

DTC P2123
Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage

DTC P2125
Accelerator Pedal Position (APP) Sensor 2 Circuit

DTC P2127
Accelerator Pedal Position (APP) Sensor 2 Circuit Low Voltage

DTC P2128
Accelerator Pedal Position (APP) Sensor 2 Circuit High Voltage

DTC P2138
Accelerator Pedal Position (APP) Sensor 1-2 Correlation

DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection






TYPICAL SCAN TOOL DATA

APP Sensor 1:




APP Sensor 2:






CIRCUIT/SYSTEM DESCRIPTION
The throttle actuator control (TAC) system uses two accelerator pedal position (APP) sensors to monitor the accelerator pedal position. The APP sensors 1 and 2 are located within the pedal assembly. Each sensor has the following circuits:
- A 5-Volt reference circuit
- A low reference circuit
- A signal circuit

Two processors are also used to monitor the TAC system data. Both processors are located within the engine control module (ECM). Each signal circuit provides both processors with a signal voltage proportional to pedal movement. The processors share and monitor data to verify that the indicated APP calculation is correct.

CONDITIONS FOR RUNNING DTC P2120, P2122, P2123, P2125, P2127, P2128
- The system voltage is more than 5.23 volts.
- The ignition is in the Unlock/Accessory, Run, or Crank position.
- DTC P0641, P0651, or P0606 is not set.
- The DTCs run continuously when the above conditions are met.

CONDITIONS FOR RUNNING DTC P2138
- The system voltage is more than 5.23 volts.
- The ignition is in the Unlock/Accessory or Run position.
- DTC P0641, P0651, P0606, P2120, P2122, P2123, P2125, P2127, or P2128 is not set.
- The DTC runs continuously when the above conditions are met.

CONDITIONS FOR SETTING DTC P2120
The ECM detects that APP sensor 1 voltage is less than 0.33 volt or more than 4.59 volts for more than 0.5 second.

CONDITIONS FOR SETTING DTC P2122
The ECM detects that APP sensor 1 voltage is less than 0.33 volt for more than 0.5 second.

CONDITIONS FOR SETTING DTC P2123
The ECM detects that APP sensor 1 voltage is more than 4.59 volts for more than 0.5 second.

CONDITIONS FOR SETTING DTC P2125
The ECM detects that APP sensor 2 voltage is less than 0.16 volt or more than 2.30 volts for more than 0.5 second.

CONDITIONS FOR SETTING DTC P2127
The ECM detects that APP sensor 2 voltage is less than 0.16 volt for more than 0.5 second.

CONDITIONS FOR SETTING DTC P2128
The ECM detects that APP sensor 2 voltage is more than 2.30 volts for more than 0.5 second.

CONDITIONS FOR SETTING DTC P2138
The ECM detects that the difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for more than 0.5 second.

ACTION TAKEN WHEN THE DTC SETS
- The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
- The control module commands the TAC system to operate in the Reduced Engine Power mode.
- A message center or an indicator displays Reduced Engine Power.
- Under certain conditions the control module commands the engine OFF.

CONDITIONS FOR CLEARING THE MIL/DTC
- The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
- A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
- Clear the MIL and the DTC with a scan tool.

CIRCUIT/SYSTEM VERIFICATION
1. With the ignition ON and the engine OFF, observe the DTC information on the scan tool.
- If DTC P0641 or P0651 is also set, diagnose those DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle. Diagnostic Trouble Code Descriptions
2. With the accelerator pedal in the rest position, observe the APP Sensor 1 parameter with the scan tool. The voltage should be between 0.33-4.59 volts.
- If the voltage is outside of the range, continue with Circuit/System Testing.
3. Observe the APP Sensor 2 parameter with the scan tool. The voltage should be between 0.16-2.30 volts.
- If the voltage is outside of the range, continue with Circuit/System Testing.
4. Observe the APP Sensor 1 and 2 parameter with the scan tool. The sensors should indicate Agree.
- If the sensors indicate Disagree, continue with Circuit/System Testing.
5. Clear the DTCs with a scan tool.
6. Turn OFF the ignition for 60 seconds.
7. Operate the vehicle within the conditions for running the DTCs.
8. With the ignition ON and the engine OFF, observe the previous APP sensor parameters and DTC information, with the scan tool.
- If DTC P2120 or P2125 is set, and all of the previous APP sensor parameters are normal, replace the ECM.
- If any of the previous APP sensor parameters are now abnormal or out of range, continue with Circuit/System Testing.

CIRCUIT/SYSTEM TESTING
1. Turn OFF the ignition.
2. Disconnect the accelerator pedal harness connector.
3. With the ignition ON and the engine OFF, observe the APP Sensor 1 and APP Sensor 2 parameters on the scan tool. The voltage should be less than 0.1 volt.
- If the voltage is more than 0.1 volt, test the affected signal circuit for a short to voltage or a faulty ECM.
4. Measure for 4.8-5.2 volts between each of the 5-Volt reference circuits and the negative terminal of the battery.
- If the voltage is more than 5.2 volts, test the affected 5-Volt reference circuit for a short to voltage or faulty ECM.
- If the voltage is less than 4.8 volts, test the affected 5-Volt reference circuit for an open, short to ground, or a faulty ECM.
5. Install a 3-amp fused jumper wire between the signal circuit and the 5-Volt reference circuit of the APP sensor 1. Observe the APP Sensor 1 parameter on the scan tool. The voltage should be more than 4.8 volts.
- If the voltage is less than 4.8 volts, test the APP sensor 1 signal circuit for an open, a short to ground, or a faulty ECM.
6. Install a 3-amp fused jumper wire between the signal circuit and the 5-Volt reference circuit of the APP sensor 2. Observe the APP Sensor 2 parameter on the scan tool. The voltage should be more than 4.8 volts.
- If the voltage is less than 4.8 volts, test the APP sensor 2 signal circuit for an open, a short to ground, or a faulty ECM.
7. Measure for 4.8-5.2 volts between one of the 5-Volt reference circuits and each of the low reference circuits.
- If the voltage is less than 4.8 volts, test the affected low reference circuit for an open, or a faulty ECM.
8. Turn OFF the ignition.
9. Disconnect the ECM harness connector, and measure the 5-Volt reference, the low reference, and each of the signal circuits between the ECM and the accelerator pedal for less than 5 ohms.
- If the resistance is more than 5 ohms, repair the affected circuit.
10. Test the signal circuits for continuity between them.
- If continuity exists between the signal circuits, repair the short.
11. If all circuits test normal, replace the accelerator pedal.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Control Module References for ECM replacement, setup, and programming.
- Accelerator Pedal Position (APP) Sensor Replacement Verification Tests
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