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P2121






P2121-ACCELERATOR PEDAL POSITION SENSOR 1 PERFORMANCE





For a complete wiring diagram refer to the Wiring Information Electrical Diagrams.

Theory of Operation

The throttle pedal produces two voltage signals proportional to the pedal movement. The primary signal varies between 0 and 5 volts and the secondary signal varies between 0 and 2.5 volts. The Engine Control Module uses the two signals to validate throttle pedal position to control engine fueling. The ECM illuminates the MIL lamp and ETC light solid immediately after the diagnostic runs and fails. Acceleration rate and Engine output are limited. The ECM will turn off the MIL lamp after the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
While the engine is running.

- Set Condition:
The ECM detected a conformance error between APPS 1 and APPS 2.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure

1. OTHER DTCS PRESENT
1. Using the scan tool, check for any additional APPS fault codes.

Do you have any additional APPS faults?

Yes

- Troubleshoot other DTCs first,
- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test

2. APPS HARNESS
1. Verify that the APPS is connected.
2. Inspect the harness and the APPS connector.

Are any pins damaged?

Yes

- Repair or replace the harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 3

3. APPS
1. Monitor the APPS 1 and APPS 2 voltage with the scan tool while depressing the accelerator pedal.

Is the voltage transition shown on the scan tool smooth while depressing the accelerator pedal and is the voltage from APPS 1 twice as much as the voltage from APPS 2?

Yes

- Go To 4

No

- Replace the APPS.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

4. (K23) APPS 1 SIGNAL CIRCUIT OPEN




1. Disconnect the C2 ECM harness connector.
2. Disconnect the APPS harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance of the (K23) APPS 1 Signal circuit between the APPS connector and the ECM C2 connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 5

No

- Repair the open in the (K23) APPS 1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

5. (K852) 5-VOLT SUPPLY CIRCUIT OPEN




1. Measure the resistance of the (K852) 5-volt Supply circuit between the APPS connector and the ECM C2 connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 6

No

- Repair the open in the 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

6. (K23) APPS 1 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the APPS 1 Signal circuit at the sensor connector.

Is the resistance greater than 10K ohms?

Yes

- Go To 7

No

- Repair the short to ground in the (K23) APPS 1 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

7. (K23) APPS 1 SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the (K23) APPS 1 Signal circuit and all other circuits in the ECM C2 connector.

Is the resistance below 10K ohms between the (K23) APPS 1 Signal circuit and any other circuit?

Yes

- Repair the short between the (K23) APPS Signal circuit and the circuit that measured below 10k ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 8

8. (K852) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND




1. Measure the resistance between the ground and the (K852) 5-volt Supply circuit at the sensor connector.

Is the resistance greater than 10k ohms?

Yes

- Repair the short to ground in the (K852) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 9

9. (K852) 5-VOLT SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the (K852) 5-volt Supply circuit and all other circuits in ECM C2 harness connector.

Is the resistance below 10K ohms between the (K852) 5-volt Supply circuit and any other circuit?

Yes

- Repair the short between the (K852) 5-volt Supply circuit and the circuit that measured below 10k ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 10

10. (K167) APPS 1 RETURN CIRCUIT OPEN




1. Measure the resistance of the (K167) APPS 1 Return circuit between the sensor connector and the ECM C2 connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 11

No

- Repair the open in the (K167) APPS Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

11. (K23) APPS 1 SIGNAL CIRCUIT SHORTED TO (K852) 5-VOLT SUPPLY CIRCUIT




1. Measure the resistance between the (K23) APPS 1 Signal circuit and the (K852) 5-volt Supply circuit at the sensor harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (K23) APPS Signal circuit and the (K852) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 12

12. (K167) APPS 1 RETURN CIRCUIT SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the (K167) APPS 1 Return circuit at and all other circuits in the ECM C2 harness connector.

Is the resistance below 10.0 ohms?

Yes

- Repair the short between the (K167) APPS 1 Return circuit and the circuit that measured below 10k ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 13

13. (K29) APPS 2 SIGNAL CIRCUIT OPEN




1. Measure the resistance of the (K29) APPS 2 Signal circuit between the APPS connector and the ECM C2 harness connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 14

No

- Repair the open in the (K29) APPS 2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

14. (F854) 5-VOLT SUPPLY CIRCUIT OPEN




1. Measure the resistance of the (F854) 5-volt Supply circuit between the APPS connector and the ECM C2 connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 15

No

- Repair the open in the (F854) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

15. (K29) APPS 2 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K29) APPS 2 Signal circuit at the sensor connector.

Is the resistance below 10k ohms?

Yes

- Repair the short to ground in the (K29) APPS 2 Signal circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 16

16. (K29) APPS 2 SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the (K29) APPS 2 Signal circuit and all other circuits in the ECM C2 harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (K29) APPS 2 Signal circuit and the circuit that measured below 10k ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 17

17. (F854) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (F854) 5-volt Supply circuit at the sensor connector.

Is the resistance below 10k ohms?

Yes

- Repair the short to ground in the (F854) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 18

18. (F854) 5-VOLT SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the (F854) 5-volt Supply circuit and all other circuits in the ECM C2 harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (F854) 5-volt Supply circuit and the circuit that measured below 10k ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 19

19. (K400) APPS 2 RETURN CIRCUIT OPEN




1. Measure the resistance of the (K400) APPS 2 Return circuit between the APPS harness connector and the ECM C2 harness connector.

Is the resistance below 10.0 ohms?

Yes

- Go To 20

No

- Repair the open in the (K400) APPS 2 Return circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

20. (K29) APPS 2 SIGNAL CIRCUIT SHORTED TO (F854) 5-VOLT SUPPLY CIRCUIT




1. Measure the resistance between the (K29) APPS 2 Signal circuit and the (F854) 5-volt Supply circuit in the APPS harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (K29) APPS 2 Signal circuit and the (F854) 5-volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 21

21. (K400) APPS 2 RETURN CIRCUIT SHORTED TO OTHER CIRCUITS
1. Measure the resistance between the (K400) APPS 2 Return circuit and all other circuits in the ECM C2 harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (K400) APPS 2 Return circuit and the circuit that measured below 10k ohms.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 22

22. ECM
1. Reconnect the ECM connectors.
2. Reconnect the APPS connector.
3. Turn Ignition on, engine off.
4. While monitoring with the scan tool, disconnect the sensor connector.

Did a APPS 1 and APPS 2 voltage too low DTC set?

Yes

- Go To 23

No

- Replace the ECM.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

23. APPS
1. Reconnect the APPS connector.
2. Monitor the APPS 1 and APPS 2 voltage with the scan tool while depressing the accelerator pedal.

Is the voltage transition shown on the scan tool smooth while depressing the accelerator and is the voltage from APPS 1 twice as much as the voltage from APPS 2?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition Test

No

- Replace the APPS.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

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