FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.
Home >> Dodge or Ram Truck >> 2012 >> RAM 3500 Truck 2WD L6-6.7L DSL Turbo High Output >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P2121

P2121






P2121-ACCELERATOR PEDAL POSITION SENSOR 1 PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The throttle pedal produces two voltage signals proportional to the pedal position. The primary signal varies between 0 and 5.0 Volts and the secondary signal varies between 0 and 2.5 Volts. The Powertrain Control Module (PCM) uses the two signals to validate throttle pedal position to control engine fueling. The PCM illuminates the MIL lamp and ETC light solid immediately after the diagnostic runs and fails. Acceleration rate and engine output are limited. The PCM will turn off the MIL lamp after the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Any time the Powertrain Control Module is powered up.

- Set Condition:
The Powertrain Control Module (PCM) 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 APP Sensor fault codes.

Do you have any additional APP Sensor faults?

Yes

- Troubleshoot other DTCs first,
- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. APP SENSOR HARNESS
1. Verify that the APP Sensor harness connector is connected.
2. Inspect the harness and the APP Sensor harness 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. CHECK THE APP SENSOR
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 +/- 3% as the voltage from APPS 2?

Yes

- Go To 4

No

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

4. CHECK THE (K23) APP SENSOR 1 SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Disconnect the C2 PCM harness connector.
2. Disconnect the APP Sensor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance of the (K23) APPS 1 Signal circuit between the APP Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 5

No

- Repair the (K23) APPS 1 Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (F855) 5-Volt Supply circuit between the APP Sensor connector and the PCM C2 connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 6

No

- Repair the (F855) 5-Volt Supply circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. CHECK THE (K23) APP SENSOR 1 SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the APP Sensor 1 Signal circuit at the APP Sensor harness connector.

Is the resistance above 10K Ohms?

Yes

- Go To 7

No

- Repair the (K23) APP Sensor 1 Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. CHECK FOR THE (K23) APP SENSOR 1 SIGNAL CIRCUIT SHORTED TO ANOTHER CIRCUIT
1. Measure the resistance between the (K23) APP Sensor 1 Signal circuit and all other circuits in the PCM 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) APP Sensor 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. CHECK THE (F855) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between the ground and the (F855) 5-Volt Supply circuit at the APP Sensor harness connector.

Is the resistance above 10k Ohms?

Yes

- Repair the (F855) 5-Volt Supply circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 9

9. CHECK FOR THE (F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO ANOTHER CIRCUIT
1. Measure the resistance between the (F855) 5-Volt Supply circuit and all other circuits in PCM C2 harness connector.

Is the resistance below 10K Ohms between the (F855) 5-Volt Supply circuit and any other circuit?

Yes

- Repair the short between the (F855) 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. CHECK THE (K167) APP SENSOR 1 RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K167) APP Sensor 1 Return circuit between the APP Sensor connector and the PCM C2 connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 11

No

- Repair the (K167) APP Sensor Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

11. CHECK FOR THE (K23) APP SENSOR 1 SIGNAL CIRCUIT SHORTED TO THE (F855) 5-VOLT SUPPLY CIRCUIT




1. Measure the resistance between the (K23) APP Sensor 1 Signal circuit and the (F855) 5-Volt Supply circuit at the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K23) APP Sensor Signal circuit and the (F855) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 12

12. CHECK FOR THE (K167) APP SENSOR 1 RETURN CIRCUIT SHORTED TO ANOTHER CIRCUIT
1. Measure the resistance between the (K167) APP Sensor 1 Return circuit at and all other circuits in the PCM C2 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K167) APP Sensor 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. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K29) APP Sensor 2 Signal circuit between the APP Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 14

No

- Repair the (K29) APP Sensor 2 Signal circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

14. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (F856) 5-Volt Supply circuit between the APP Sensor harness connector and the PCM C2 connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 15

No

- Repair the (F856) 5-Volt Supply circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

15. CHECK THE (K29) APP SENSOR 2 SIGNAL CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (K29) APP Sensor 2 Signal circuit at the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the (K29) APP Sensor 2 Signal circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 16

16. CHECK FOR THE (K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO ANOTHER CIRCUIT
1. Measure the resistance between the (K29) APP Sensor 2 Signal circuit and all other circuits in the PCM C2 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K29) APP Sensor 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. CHECK THE (F856) 5-VOLT SUPPLY CIRCUIT FOR A SHORT TO GROUND




1. Measure the resistance between ground and the (F856) 5-Volt Supply circuit at the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the (F856) 5-Volt Supply circuit for a short to ground.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 18

18. CHECK FOR THE (F856) 5-VOLT SUPPLY CIRCUIT SHORTED TO ANOTHER CIRCUIT
1. Measure the resistance between the (F856) 5-Volt Supply circuit and all other circuits in the PCM C2 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (F856) 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. CHECK THE (K400) APP SENSOR 2 RETURN CIRCUIT FOR AN OPEN/HIGH RESISTANCE
1. Measure the resistance of the (K400) APP Sensor 2 Return circuit between the APP Sensor harness connector and the PCM C2 harness connector.

Is the resistance below 5.0 Ohms?

Yes

- Go To 20

No

- Repair the (K400) APP Sensor 2 Return circuit for an open or high resistance.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

20. CHECK FOR THE (K29) APP SENSOR 2 SIGNAL CIRCUIT SHORTED TO THE (F856) 5-VOLT SUPPLY CIRCUIT




1. Measure the resistance between the (K29) APP Sensor 2 Signal circuit and the (F856) 5-Volt Supply circuit in the APP Sensor harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K29) APP Sensor 2 Signal circuit and the (F856) 5-Volt Supply circuit.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 21

21. CHECK FOR THE (K400) APP SENSOR 2 RETURN CIRCUIT SHORTED TO ANOTHER CIRCUIT
1. Measure the resistance between the (K400) APP Sensor 2 Return circuit and all other circuits in the PCM C2 harness connector.

Is the resistance below 10k Ohms?

Yes

- Repair the short between the (K400) APP Sensor 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. POWERTRAIN CONTROL MODULE
1. Reconnect the PCM connectors.
2. Reconnect the APP Sensor connector.
3. Turn Ignition on, engine off.
4. While monitoring with the scan tool, disconnect the APP Sensor harness connector.

Did a APP Sensor 1 and APP Sensor 2 voltage low DTC set?

Yes

- Go To 23

No

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

23. APP SENSOR
1. Reconnect the APP Sensor harness connector.
2. Monitor the APP Sensor 1 and APP Sensor 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 APP Sensor 1 twice as much +/- 3% as the voltage from APP Sensor 2?

Yes

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

No

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

pro multis Credits:Operation CHARM About Operation CHARM