P2123
DTC P2122, P2123, 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 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 accelerator pedal assembly contains 2 accelerator pedal position (APP) sensors. The APP sensors are mounted to the accelerator pedal assembly and are not serviceable. The APP sensors provide a signal voltage that changes relative to pedal position. The engine control module (ECM) supplies each APP sensor with a 5 V reference circuit, a low reference circuit, and a signal circuit.
Both the APP sensors 1 and 2 signal percentages increase as the pedal is depressed, from approximately 0 percent at rest to above 95 percent when fully depressed.
Conditions for Running the DTC
P2122, P2123, P2127, or P2128
* DTC P06A3 or P0697 are not set.
* The ignition is ON or the engine is operating.
* The ignition voltage is greater than 6 V.
* The ECM is not commanding reduced power.
* The DTCs run continuously when the above conditions are met.
P2138
* DTCs P06A3, P0697, P2122, P2123, P2127, or P2128 are not set.
* The ignition is ON or the engine is operating.
* The ignition voltage is greater than 6 V.
* The ECM is not commanding reduced power.
* The DTC runs continuously when the above conditions are met.
Conditions for Setting the DTC
P2122
The ECM detects that the APP sensor 1 voltage is less than 0.46 V for less than 1 s.
P2123
The ECM detects that the APP sensor 1 voltage is greater than 4.7 V for less than 1 s.
P2127
The ECM detects that the APP sensor 2 voltage is less than 0.32 V for less than 1 s.
P2128
The ECM detects that the APP sensor 2 voltage is greater than 2.6 V for less than 1 s.
P2138
The ECM detects that APP sensor 1 and APP sensor 2 disagree greater than 10 percent for less than 1 s.
OR
The ECM detects that both APP sensor 1 and APP sensor 2 are 5 percent greater than the learned minimum position for less than 1 s.
Action Taken When the DTC Sets
* DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.
* The ECM commands the TAC system to operate in a Reduced Engine Power mode.
Conditions for Clearing the DTC
DTCs P2122, P2123, P2127, P2128, and P2138 are type A DTCs.
Diagnostic Aids
* A high resistance condition on the accelerator pedal position circuits could cause a DTC to set.
* Ensure that the in-line harness connector seals are installed correctly. Improper installation could result in water intrusion into the connector and cause a DTC to set.
Reference Information
Schematic Reference
Engine Controls Schematics ((LFX)) [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 for scan tool information
Circuit/System Verification
1. Ignition ON.
2. Verify DTC P0697 or P06A3 is not set.
• If any of the DTCs are set
Refer to DTC P0641, P0651, P0697, or P06A3 (ECM) Powertrain Management (ECM) for further diagnosis.
• If none of the DTCs are set
3. Verify the APP Sensor 1 Circuit Status and APP Sensor 2 Circuit Status displays OK.
• If Malfunction is displayed
Refer to Circuit/System Testing
• If OK is displayed
4. Verify the scan tool APP Sensor 1 and 2 Agree/Disagree parameter displays Agree while performing the tests listed below:
* 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.
• If Disagree
Refer to Circuit/System Testing
• If Agree
5. Verify that DTC P2122, P2123, P2127, P2128, or P2138 is not set.
• If any of the DTCs are set
Refer to Circuit/System Testing
• If none of the DTCs set
6. 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.
7. Verify the DTC does not set.
• If the DTC sets
Refer to Circuit/System Testing
• If the DTC does not set
8. All OK
Circuit/System Testing
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B107 accelerator pedal assembly. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohms between each low reference circuit terminal listed below and ground.
* Low reference circuit terminal 4 or A
* Low reference circuit terminal 5 or D
• If 5 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If less than 5 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between each 5 V reference circuit terminal listed below and ground.
* 5 V reference circuit terminal 1 or C
* 5 V reference circuit terminal 2 or F
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the 5 V reference circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the 5 V reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If between 4.8-5.2 V
5. Verify each APP sensor voltage parameter is less than 0.2 V.
• If 0.2 V or greater
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the signal circuit terminal listed below and ground.
* APP sensor 1 signal circuit terminal 3 or E
* APP sensor 2 signal circuit terminal 6 or B
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If less than 0.2 V
6. Install a 3 A fused jumper wire between each signal circuit terminal listed below and the 5 V reference circuit terminal 1 or C.
* APP sensor 1 signal circuit terminal 3 or E
* APP sensor 2 signal circuit terminal 6 or B
7. Verify the scan tool APP sensor voltage parameter is greater than 4.8 V.
• If 4.8 V or less
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the signal circuit terminal and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If greater than 4.8 V
8. Test or replace the B107 accelerator pedal assembly.
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 for ECM replacement, programming, and setup