P2127
DTC P2120, P2122, P2123, P2125, P2127, P2128, or P2138
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovide an overview of each diagnostic category.
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
Typical Scan Tool Data
Circuit/System Description
The accelerator pedal assembly contains two accelerator pedal position (APP) sensors. The APP sensors are mounted in the pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to the position of the accelerator pedal. The Engine Control Module (ECM) supplies a separate 5 V reference and low reference circuit for each of the APP sensors.
Conditions for Running the DTC
P2120, P2122, P2123, P2125, P2127, P2128
* DTC P0641 and P0651 are not set.
* The run/crank or powertrain relay voltage is greater than 6 V and reduced power is not active.
* The ignition is in the Unlock/Accessory or Run position.
* DTC P2120, P2122, P2123, P2125, P2127, P2128 run continuously when the above conditions are met.
P2138
* DTC P0641, P0651, P2120, P2125 are not set.
* The system voltage is greater than 5.23 V.
* The ignition is in the Unlock/Accessory or Run position.
* DTC P2138 runs continuously when the above conditions are met.
Conditions for Setting the DTC
P2120
The APP sensor 1 voltage is less than 0.325 V, or greater than 4.75 V for greater than 0.4 s.
P2122
The ECM detects that the APP sensor 1 voltage is less than 0.325 V for greater than 0.4 s.
P2123
The ECM detects that the APP sensor 1 voltage is greater than 4.75 V for greater than 0.4 s.
P2125
The APP sensor 2 voltage is less than 0.325 V, or greater than 4.75 V for greater than 0.4 s.
P2127
The ECM detects that the APP sensor 2 voltage is less than 0.325 V for greater than 0.4 s.
P2128
The ECM detects that the APP sensor 2 voltage is greater than 4.75 V for greater than 0.4 s.
P2138
The voltage difference between APP sensor 1 and APP sensor 2 exceeds a predetermined value for greater than 2 s.
Action Taken When the DTC Sets
* DTCs P2120, P2122, P2123, P2125, P2127, P2128, and P2138 are Type A DTCs.
* 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
DTCs P2120, P2122, P2123, P2125, P2127, P2128, and P2138 are Type A DTCs.
Reference Information
Schematic Reference
Engine Controls Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Throttle Actuator Control (TAC) System Description Throttle Actuator Control (TAC) System Description
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Programming and Relearningfor scan tool information
Circuit/System Verification
1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description Hybrid Modes of Operation.
2. Ignition ON, verify the scan tool hood position parameter displays Open.
• If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
3. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0641 or P0651 are not set.
• If a DTC is set, refer to DTC P0641 or P0651 P0641 for further diagnosis.
4. Ignition ON, observe the scan tool APP Sensor 1 and 2 voltage parameters. Both readings should be between 0.30-1.2 V, and change with accelerator pedal input.
5. Observe the scan tool APP Sensor 1 and 2 Agree/Disagree parameter while performing the following tests:
* Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times.
* Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.
The APP Sensor 1 and 2 Agree/Disagree parameter should display Agree.
6. Clear the DTCs with the scan tool. Operate the vehicle within the Conditions for Running the DTC, or within the conditions that you observed from the Freeze Frame/Failure Records.
7. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P2120 or P2125 are the only DTCs set.
• If DTC P2120 or P2125 are the only DTCs set, replace the ECM.
8. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the accelerator pedal.
2. Ignition OFF for 2 minutes and the scan tool powered OFF, test for less than 5 ohm between the appropriate low reference circuit terminal listed below and ground.
* APP sensor 1 terminal F
* APP sensor 2 terminal A
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 V between the appropriate 5-volt reference circuit terminal listed below and ground.
* APP sensor 1 terminal D
* APP sensor 2 terminal C
• If less than the specified range, test the 5-volt reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Verify the scan tool APP sensor 1 and 2 voltages are less than 0.3 V.
• If greater than the specified range, test the APP sensor 1 and 2 signal circuits terminals B and E for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3 A fused jumper wire between the APP sensor 1 signal circuit terminal E and the 5-volt reference circuit terminal D. Verify the scan tool APP sensor 1 voltage parameter is greater than 4.8 V.
• If less than the specified range, test the APP sensor 1 signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
6. Install a 3 A fused jumper wire between the APP sensor 2 signal circuit terminal B and the 5-volt reference circuit terminal D. Verify the scan tool APP sensor 2 voltage parameter is greater than 4.8 V.
• If less than the specified range, test the APP sensor 2 signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
7. If all circuits and connections test normal, test or replace the Accelerator Pedal Position Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Accelerator Pedal Position Sensor Replacement Service and Repair
* Control Module References Programming and Relearningfor ECM replacement, setup, and programming