P2138
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% at rest to above 95% when fully depressed.
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 throttle actuator control system to operate in reduced engine power mode.
Conditions for Clearing the DTC
DTCs P2122, P2123, P2127, P2128, and P2138 are Type A DTCs.
Diagnostic Aids
* If a shared 5 V reference circuit is shorted to ground or shorted to a voltage, other 5 V reference circuits may be affected.
* The scan tool 5 V reference parameter should display between 4.8-5.2 V.
* A high resistance condition on the accelerator pedal position (APP) sensor circuits may cause a DTC to set.
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 for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify DTCs P0697 or P06A3 are not set.
• If a DTC is set, refer to DTC P0641, P0651, P0697, or P06A3 (ECM) Powertrain Management (ECM).
2. Ignition ON, observe the scan tool APP Sensor 1 and 2 Indicated parameters. Both parameters should be 0%.
3. 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.
4. Observe the DTC information with a scan tool. DTCs P2122, P2123, P2127, P2128, or P2138 should not set.
5. 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 B107 Accelerator Pedal Position Sensor harness connector at the accelerator pedal assembly.
2. Ignition OFF for 1 min, test for less than 5 ohms between the B107 Accelerator Pedal Position Sensor low reference circuit terminals listed below and ground.
* Low reference circuit terminal 3
* Low reference circuit terminal 4
• If greater than the specified range, test the low reference circuit for a short to voltage, or 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 both 5 V reference circuit terminals listed below and ground.
* 5 V reference circuit terminal 1
* 5 V reference circuit terminal 6
• If less than the specified range, test the 5 V reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
4. Verify the appropriate APP sensor voltage parameter is at 0 V.
• If greater than the specified range, test the appropriate signal circuit terminal listed below for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.
* APP sensor 1 signal circuit terminal 2
* APP sensor 2 signal circuit terminal 5
5. Install a 3 A fused jumper wire between the appropriate signal circuit terminal listed below and the 5 V reference circuit terminal 1 of the appropriate B107 Accelerator Pedal Position Sensor. Verify the appropriate APP Sensor voltage parameter is greater than 4.8 V.
* APP sensor 1 signal circuit terminal 2
* APP sensor 2 signal circuit terminal 5
• If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.
6. If all circuits test normal, replace the B107 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 Control Module References for ECM replacement, programming and setup