P2138
DTC P2122, P2123, P2127, P2128, or P2138 (LUW)
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 Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P2122
- Accelerator Pedal Position (APP) Sensor 1 Circuit Low Voltage
DTC P2123
- Accelerator Pedal Position (APP) Sensor 1 Circuit High Voltage
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) Sensors 1-2 Not Plausible
Diagnostic Fault Information
Typical Scan Tool Data
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 a 5 V reference circuit, a low reference circuit, and a signal circuit.
Two processors are also used to monitor the TAC motor 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 sensor calculation is correct.
Conditions for Running the DTC
P2122, P2123, P2127, P2128
* The system voltage is greater than 6.4 V.
* The ignition is in the unlock, accessory, run, or crank position.
* DTC P06A3 or P0697 are not set.
* The DTCs run continuously when the above conditions are met.
P2138
* The system voltage is greater than 6.4 V.
* The ignition is in the unlock, accessory or run position.
* DTC P06A3, P0697, P2122, P2123, P2127 or P2128 are not set.
* The DTC runs continuously when the above conditions are met.
Conditions for Setting the DTC
P2122
The ECM detects that APP sensor 1 voltage is less than 0.5 V for greater than 0.5 s.
P2123
The ECM detects that APP sensor 1 voltage is greater than 4.75 V for greater than 0.5 s.
P2127
The ECM detects that APP sensor 2 voltage is less than 0.3 V for greater than 0.5 s.
P2128
The ECM detects that APP sensor 2 voltage is greater than 2.6 V for greater than 0.5 s.
P2138
The ECM detects that the 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 P2122, P2123, P2127, P2128 and P2138 are Type A DTCs.
* The ECM commands the TAC motor system to operate in reduced engine power mode.
Conditions for Clearing the DTC
DTCs P2122, P2123, 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 Fuel Pump and Level Sensor Assembly
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 Control Module References
Circuit/System Verification
1. Ignition ON, observe the scan tool APP Sensor 1 Position parameter. The reading should be between 0.46-4.75 V, and change with the accelerator pedal input.
2. Ignition ON, observe the scan tool APP Sensor 2 Position parameter. The reading should be between 0.32-2.6 V, and change with the accelerator pedal input.
3. Clear the DTCs with the scan tool.
4. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.
5. Verify that the following DTCs are not set: DTC P06A3, P0697, P2122, P2123, P2127 or P2128 are not set.
• If DTCs P06A3, P0697, P2122, P2123, P2127 or P2128 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.
Circuit/System Testing
1. Ignition OFF for 90 s, disconnect the harness connector at the B107 Accelerator Pedal Position Sensor.
2. Test for less than 3 ohms between each of the B107 Accelerator Pedal Position Sensor low reference circuit terminals 3 and 4 and ground.
• If greater than 3 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
3. Ignition ON, test for 4.8-5.2 V between each of the B107 Accelerator Pedal Position Sensor 5 V reference circuit terminals 1 and 6 and ground.
• If less than 4.8 V, test affected 5 V reference circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
• If greater than 5.2 V test affected 5 V reference circuit for short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
4. Ignition ON, verify the scan tool APP sensor 1 and 2 voltages are less than 0.1 V.
• If greater than 0.1 V, test the B107 Accelerator Pedal Position Sensor 1 and 2 signal circuits terminal 2 and 5 for a short to voltage. If the circuits tests normal, replace the K20 Engine Control Module.
5. Install a 3 A fused jumper wire between the signal circuit terminal 5 and the 5 V reference circuit terminal 6 of the B107 Accelerator Pedal Position Sensor 1, verify the APP sensor 1 voltage is greater than 4.8 V.
• If less than 4.8 V, test the B107 Accelerator Pedal Position Sensor 1 signal circuit for an open or short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
6. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the 5 V reference circuit terminal 1 of the B107 Accelerator Pedal Position Sensor 2. Verify that the APP sensor 2 voltage is greater than 4.8 V.
• If less than 4.8 V, test the B107 Accelerator Pedal Position Sensor 2 signal circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the K20 Engine Control Module.
7. If all circuits test normal replace the B107 Accelerator Pedal Position Sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Accelerator Pedal Position Sensor Replacement Service and Repair
* Control Module References Control Module References