P2122

P2122-ACCELERATOR PEDAL POSITION SENSOR 1 CIRCUIT LOW





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 (ECM) 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:
With the ignition on and no other APPS No.1 DTCs present.

- Set Condition:
When the APP Sensor No.1 voltage is below 0.25 volts for five seconds.





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

1. APP SENSOR BELOW 0.25 OF A VOLT

NOTE: When this DTC is Active the engine speed, torque, and vehicle speed are limited to a Limp in mode.

1. Ignition on, engine not running.
2. With a scan tool, read the APP Sensor No.1 voltage.

Is the voltage below 0.25 of a volt?

Yes

- Go To 2

No

- Go To 11

2. (K852) 5-VOLT SUPPLY CIRCUIT




1. Turn the ignition off.
2. Disconnect the APP Sensor harness connector.
3. Ignition on, engine not running.
4. Measure the voltage on the (K852) 5-volt Supply circuit in the APP Sensor harness connector.

Is the voltage between 4.9 and 5.1 volts?

Yes

- Go To 3

No

- Go To 8

3. ACCELERATOR PEDAL POSITION SENSOR




1. Connect a jumper wire between the (K852) 5-volt Supply circuit and the (K23) APP Sensor No.1 Signal circuit in the Sensor harness connector.
2. With a scan tool, monitor the APP Sensor No.1 voltage.

Is the voltage reading between 4.9 and 5.1 volts?

Yes

- Replace the APP Sensor Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 4

4. (K23) APP SENSOR NO.1 SIGNAL CIRCUIT OPEN





NOTE: Remove the jumper wire before continuing.

1. Turn the ignition off.
2. Disconnect the C2 ECM harness connector.
3. Measure the resistance of the (K23) APP Sensor No.1 Signal circuit from the APP Sensor harness connector to the C2 ECM harness connector.

Is the resistance below 5.0 ohms?

Yes

- Go To 5

No

- Repair the open or high resistance in the (K23) APP Sensor No.1 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

5. (K23) APP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO GROUND




1. Measure the resistance between ground and the (K23) APP Sensor No.1 Signal circuit in the APP Sensor harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short to ground in the (K23) APP Sensor No.1 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 6

6. (K23) APP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (K167) APP SENSOR NO.1 RETURN CIRCUIT




1. Measure the resistance between the (K23) APP Sensor No.1 Signal circuit and the (K167) Sensor No.1 Return circuit at the APP Sensor harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (K167) APP Sensor No.1 Return circuit and the (K23) APP Sensor No.1 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 7

7. (K23) APP SENSOR NO.1 SIGNAL CIRCUIT SHORTED TO THE (K400) APP SENSOR NO.2 RETURN CIRCUIT




1. Measure the resistance between the (K23) APP Sensor No.1 Signal circuit and the (K400) Sensor No.2 Return circuit in the APP Sensor harness connector.

Is the resistance below 10k ohms?

Yes

- Repair the short between the (K400) APP Sensor No.2 Return circuit and the (K23) APP Sensor No.1 Signal circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Go To 10

8. (K852) 5-VOLT SUPPLY CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the C2 ECM harness connector.
3. Measure the resistance of the (K852) 5-volt Supply circuit from the Sensor harness connector to the C2 ECM harness connector.

Is the resistance below 5.0 ohms?

Yes

- Go To 9

No

- Repair the open or high resistance in the (K852) 5-volt Supply circuit.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

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




1. Measure the resistance between ground and the (K852) 5-volt Supply circuit in the APP Sensor harness connector.

Is the resistance below 10k ohms?

Yes

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

No

- Go To 10

10. ECM

NOTE: Before continuing, check the ECM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.

1. Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.

Were there any problems found?

Yes

- Repair as necessary.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Replace and program the Engine Control Module.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

11. APP SENSOR SWEEP
1. Ignition on, engine not running.
2. With a scan tool, monitor the APP Sensor No.1 voltage.
3. Slowly press the Accelerator pedal down.

Does voltage start at approximately 0.45 of a volt and go above 4.6 volts with a smooth transition?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test

No

- Replace the APP Sensor Assembly. After installation is complete, use a scan tool and select the ETC RELEARN function to relearn the APPS values.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test