To the top of the document
Orlando
   
GMDE Start Page Load static TOC Load dynamic TOC Help?

DTC P2122, P2123, P2127, P2128, or P2138

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • 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

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Accelerator Pedal Position (APP) Sensor 1 5 V Reference Circuit

P06A3

P2138

P2122

P06A3

P2138

Accelerator Pedal Position (APP) Sensor 2 5 V Reference Circuit

P0108, P0107, P0697

P2138

P2127

P0106, P0108, P0697

P2138

Accelerator Pedal Position (APP) Sensor 1 Signal

P2122

P2138

P2122

P2123, P2138

P2138

Accelerator Pedal Position (APP) Sensor 2 Signal

P2127

P2138

P2127

P2128, P2138

P2138

Accelerator Pedal Position (APP) Sensor 1 Low Reference

-

P2138

P2123

-

P2138

Accelerator Pedal Position (APP) Sensor 2 Low Reference

-

P2138

P2128

-

P2138

Typical Scan Tool Data

APP Sensor 1

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: The engine is operating at idle.

Parameter Normal Range: APP Sensor 1 0.88-1.08 V

APP Sensor 1 5 V Reference

0.00 V

0.00 V

2-5 V

APP Sensor 1 Signal

0.00 V

0.00 V

4-5 V

APP Sensor 1 Low Reference

-

4-5 V

-

APP Sensor 2

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: The engine is operating at idle.

Parameter Normal Range: APP Sensor 2 0.39-0.59 V

APP Sensor 2 5 V Reference

0.00 V

0.00 V

1-2 V

APP Sensor 2 Signal

0.00 V

0.00 V

2-5 V

APP Sensor 2 Low Reference

-

4-5 V

-

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 greater than 1 s.

P2123

The ECM detects that the APP sensor 1 voltage is greater than 4.7 V for greater than 1 s.

P2127

The ECM detects that the APP sensor 2 voltage is less than 0.32 V for greater than 1 s.

P2128

The ECM detects that the APP sensor 2 voltage is greater than 2.6 V for greater than 1 s.

P2138

The ECM detects that APP sensor 1 and APP sensor 2 disagree greater than 10 percent for greater 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 greater 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

Connector End View Reference

Component Connector End Views

Description and Operation

Throttle Actuator Control (TAC) System Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON.
  2. Verify DTC P0697 or P06A3 is not set.
    3. [ARW-LISTFAIL]

  3. If any of the DTCs are set

    Refer to DTC P0641, P0651, P0697, or P06A3 for further diagnosis.

    4. [/ARW-LISTFAIL][ARW-LISTPASS]

  4. If none of the DTCs are set

    5. [/ARW-LISTPASS]
  5. Verify the APP Sensor 1 Circuit Status and APP Sensor 2 Circuit Status displays OK.
    6. [ARW-LISTFAIL]

  6. If Malfunction is displayed

    Refer to Circuit/System Testing

    7. [/ARW-LISTFAIL][ARW-LISTPASS]

  7. If OK is displayed

    8. [/ARW-LISTPASS]
  8. Verify the scan tool APP Sensor 1 and 2 Agree/Disagree parameter displays Agree while performing the tests listed below:
    9. • 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.
    [ARW-LISTFAIL]

  9. If Disagree

    Refer to Circuit/System Testing

    10. [/ARW-LISTFAIL][ARW-LISTPASS]

  10. If Agree

    11. [/ARW-LISTPASS]
  11. Verify that DTC P2122, P2123, P2127, P2128, or P2138 is not set.
    12. [ARW-LISTFAIL]

  12. If any of the DTCs are set

    Refer to Circuit/System Testing

    13. [/ARW-LISTFAIL][ARW-LISTPASS]

  13. If none of the DTCs set

    14. [/ARW-LISTPASS]
  14. 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.
  15. Verify a DTC does not set.
    16. [ARW-LISTFAIL]

  16. If any DTC sets

    Refer to Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.

    17. [/ARW-LISTFAIL][ARW-LISTPASS]

  17. If no DTCs set

    18. [/ARW-LISTPASS]
  18. 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 Ω between each low reference circuit terminal listed below and ground.
    3. • Low reference circuit terminal 4 or A
    • Low reference circuit terminal 5 or D
    [ARW-LISTFAIL]

  3. If 5 Ω or greater

    4. [/ARW-LISTFAIL]
    2.1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    2.2. Test for less than 2 Ω in the low reference circuit end to end.
    [ARW-LISTFAIL]

  4. If 2 Ω or greater, repair the open/high resistance in the circuit.

  5. If less than 2 Ω, replace the K20 engine control module.

    6. [/ARW-LISTFAIL] [ARW-LISTPASS]

  6. If less than 5 Ω

    7. [/ARW-LISTPASS]
  7. Ignition ON.
  8. Test for 4.8-5.2 V between each 5 V reference circuit terminal listed below and ground.
    9. • 5 V reference circuit terminal 1 or C
    • 5 V reference circuit terminal 2 or F
    [ARW-LISTFAIL]

  9. If less than 4.8 V

    10. [/ARW-LISTFAIL]
    4.1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    4.2. Test for infinite resistance between the 5 V reference circuit and ground.
    [ARW-LISTFAIL]

  10. If less than infinite resistance, repair the short to ground on the circuit.

    11. [/ARW-LISTFAIL][ARW-LISTPASS]

  11. If infinite resistance

    12. [/ARW-LISTPASS]
    4.3. Test for less than 2 Ω in the 5 V reference circuit end to end.
    [ARW-LISTFAIL]

  12. If 2 Ω or greater, repair the open/high resistance in the circuit.

  13. If less than 2 Ω, replace the K20 engine control module.

    14. [/ARW-LISTFAIL] [ARW-LISTFAIL]

  14. If greater than 5.2 V

    15. [/ARW-LISTFAIL]
    4.1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
    4.2. Test for less than 1 V between the 5 V reference circuit and ground.
    [ARW-LISTFAIL]

  15. If 1 V or greater, repair the short to voltage on the circuit.

  16. If less than 1 V, replace the K20 engine control module.

    17. [/ARW-LISTFAIL] [ARW-LISTPASS]

  17. If between 4.8-5.2 V

    18. [/ARW-LISTPASS]
  18. Verify each APP sensor voltage parameter is less than 0.2 V.
    19. [ARW-LISTFAIL]

  19. If 0.2 V or greater

    20. [/ARW-LISTFAIL]
    5.1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
    5.2. 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
    [ARW-LISTFAIL]

  20. If 1 V or greater, repair the short to voltage on the circuit.

  21. If less than 1 V, replace the K20 engine control module.

    22. [/ARW-LISTFAIL][ARW-LISTPASS]

  22. If less than 0.2 V

    23. [/ARW-LISTPASS]
  23. Install a 3 A fused jumper wire between each signal circuit terminal listed below and the 5 V reference circuit terminal 1 or C.
    24. • APP sensor 1 signal circuit terminal 3 or E
    • APP sensor 2 signal circuit terminal 6 or B
  24. Verify the scan tool APP sensor voltage parameter is greater than 4.8 V.
    25. [ARW-LISTFAIL]

  25. If 4.8 V or less

    26. [/ARW-LISTFAIL]
    7.1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
    7.2. Test for infinite resistance between the signal circuit terminal and ground.
    [ARW-LISTFAIL]

  26. If less than infinite resistance, repair the short to ground on the circuit.

    27. [/ARW-LISTFAIL][ARW-LISTPASS]

  27. If infinite resistance

    28. [/ARW-LISTPASS]
    7.3. Test for less than 2 Ω in the signal circuit end to end.
    [ARW-LISTFAIL]

  28. If 2 Ω or greater, repair the open/high resistance in the circuit.

  29. If less than 2 Ω, replace the K20 engine control module.

    30. [/ARW-LISTFAIL] [ARW-LISTPASS]

  30. If greater than 4.8 V

    31. [/ARW-LISTPASS]
  31. Test or replace the B107 accelerator pedal assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

    •  Accelerator Pedal with Position Sensor Assembly Replacement
    • Control Module References for ECM replacement, programming and setup
   


© Copyright Chevrolet. All rights reserved