what is p2121
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From: mojave desert california
what is p2121
Hi all
what is code p2121 and how do i fix it my truck just stared to run bad the outher day acts like its going to stall when i did the 3 turn key trick it showed the 2121 code
what is code p2121 and how do i fix it my truck just stared to run bad the outher day acts like its going to stall when i did the 3 turn key trick it showed the 2121 code
DTR's 'Go to Guy'
Joined: Jan 2007
Posts: 3,811
Likes: 4
From: Indiana
DTR's 'Go to Guy'
Joined: Jan 2007
Posts: 3,811
Likes: 4
From: Indiana
P2121-PPS CONFORMANCE ERROR
For a complete wiring diagram Refer to Section 8W.
When Monitored:
While the engine is running
Set Condition:
The ECM detected a conformance error between PPS 1 and PPS 2
Possible Causes
OTHER DTC'S
WIRING HARNESS OR CONNECTOR DAMAGED
APPS
INTERMITTENT CONDITION
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. OTHER DTC'S PRESENT
--------------------------------------------------------------------------------
Using the scan tool, check for any additional APPS fault codes
Do you have any additiona APPS faults?
Yes
troubleshoot other DTC's first, Go To2
No
Go To12
2. APPS HARNESS
--------------------------------------------------------------------------------
Verify that the APPS is connected.
Inspect the harness and the APPS connector.
Are any pins damaged?
Yes
Repair or replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
Go To3
3. APPS
--------------------------------------------------------------------------------
Monitor the APPS 1 and APPS 2 voltage with the scan tool while depressing the acceralator pedal.
Is the voltage transition shown on the scan tool smooth while depressing the acceralator pedal and is the voltage from APPS 1 twice as much as the voltage from APPS 2?
Yes
Go To4
No
Replace the APPS.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
4. OPEN SIGNAL CIRCUIT
--------------------------------------------------------------------------------
Disconnect the ECM connectors.
Disconnect the APPS connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the APPS 1 signal circuit between the APPS sensor connector and the ECM connector.
Yes
Go To5
No
Repair or Replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
5. OPEN SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance of the APPS 1 supply circuit between the APPS sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To6
No
Repair or replace the open harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
6. SIGNAL CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 signal circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 7
No
Repair the shorted harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
7. SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 signal circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 8
No
Repair the shorted signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
8. SUPPLY CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 supply circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 9
No
Repair the Supply circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
9. SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 supply circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 10
No
Repair the supply circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
10. RETURN CIRCUIT OPEN
--------------------------------------------------------------------------------
Measure the resistance on the APPS 1 return circuit between the sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To 11
No
Repair the open return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
11. SIGNAL CIRCUIT SHORTED TO SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 signal circuit in the sensor connector and the APPS 1 supply circuit in the sensor connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 12
No
Repair the signal circuit shorted to the supply.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
12. RETURN CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 return circuit at the ECM connector and all other circuits in the ECM connector.
Yes
Go To 13
No
Repair the return circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
13. OPEN SIGNAL CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance of the APPS 2 signal circuit between the APPS sensor connector and the ECM connector.
Yes
Go To14
No
Repair or Replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
14. OPEN SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance of the APPS 2 supply circuit between the APPS sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To15
No
Repair or replace the open harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
15. SIGNAL CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 signal circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 16
No
Repair the shorted harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
16. SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 signal circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 17
No
Repair the shorted signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
17. SUPPLY CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 supply circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 18
No
Repair the Supply circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
18. SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 supply circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 19
No
Repair the supply circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
19. RETURN CIRCUIT OPEN
--------------------------------------------------------------------------------
Measure the resistance on the APPS 2 return circuit between the sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To 20
No
Repair the open return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
20. SIGNAL CIRCUIT SHORTED TO SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 signal circuit in the sensor connector and the APPS 2 supply circuit in the sensor connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 21
No
Repair the signal circuit shorted to the supply.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
21. RETURN CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 return circuit at the ECM connector and all other circuits in the ECM connector.
Yes
Go To 22
No
Repair the return circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
22. ECM
--------------------------------------------------------------------------------
Reconnect the ECM connectors.
Reconnect the APPS connector.
Turn Ignition on, engine off.
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 POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
23. APPS
--------------------------------------------------------------------------------
Reconnect the APPS connector.
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 acceraaltor and is the voltage from APPS 1 twice as much as the voltage from APPS 2?
Yes
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
Replace the APPS.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
For a complete wiring diagram Refer to Section 8W.
When Monitored:
While the engine is running
Set Condition:
The ECM detected a conformance error between PPS 1 and PPS 2
Possible Causes
OTHER DTC'S
WIRING HARNESS OR CONNECTOR DAMAGED
APPS
INTERMITTENT CONDITION
ECM
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
Diagnostic Test
1. OTHER DTC'S PRESENT
--------------------------------------------------------------------------------
Using the scan tool, check for any additional APPS fault codes
Do you have any additiona APPS faults?
Yes
troubleshoot other DTC's first, Go To2
No
Go To12
2. APPS HARNESS
--------------------------------------------------------------------------------
Verify that the APPS is connected.
Inspect the harness and the APPS connector.
Are any pins damaged?
Yes
Repair or replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
Go To3
3. APPS
--------------------------------------------------------------------------------
Monitor the APPS 1 and APPS 2 voltage with the scan tool while depressing the acceralator pedal.
Is the voltage transition shown on the scan tool smooth while depressing the acceralator pedal and is the voltage from APPS 1 twice as much as the voltage from APPS 2?
Yes
Go To4
No
Replace the APPS.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
4. OPEN SIGNAL CIRCUIT
--------------------------------------------------------------------------------
Disconnect the ECM connectors.
Disconnect the APPS connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the APPS 1 signal circuit between the APPS sensor connector and the ECM connector.
Yes
Go To5
No
Repair or Replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
5. OPEN SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance of the APPS 1 supply circuit between the APPS sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To6
No
Repair or replace the open harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
6. SIGNAL CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 signal circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 7
No
Repair the shorted harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
7. SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 signal circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 8
No
Repair the shorted signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
8. SUPPLY CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 supply circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 9
No
Repair the Supply circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
9. SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 supply circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 10
No
Repair the supply circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
10. RETURN CIRCUIT OPEN
--------------------------------------------------------------------------------
Measure the resistance on the APPS 1 return circuit between the sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To 11
No
Repair the open return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
11. SIGNAL CIRCUIT SHORTED TO SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 signal circuit in the sensor connector and the APPS 1 supply circuit in the sensor connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 12
No
Repair the signal circuit shorted to the supply.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
12. RETURN CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 1 return circuit at the ECM connector and all other circuits in the ECM connector.
Yes
Go To 13
No
Repair the return circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
13. OPEN SIGNAL CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance of the APPS 2 signal circuit between the APPS sensor connector and the ECM connector.
Yes
Go To14
No
Repair or Replace the harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
14. OPEN SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance of the APPS 2 supply circuit between the APPS sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To15
No
Repair or replace the open harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
15. SIGNAL CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 signal circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 16
No
Repair the shorted harness.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
16. SIGNAL CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 signal circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 17
No
Repair the shorted signal circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
17. SUPPLY CIRCUIT SHORTED TO GROUND
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 supply circuit at the sensor connector and battery negative.
Is the resistance greater than 100 K ohms?
Yes
Go To 18
No
Repair the Supply circuit shorted to ground.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
18. SUPPLY CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 supply circuit at the ECM connector and all other circuits in the ECM connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 19
No
Repair the supply circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
19. RETURN CIRCUIT OPEN
--------------------------------------------------------------------------------
Measure the resistance on the APPS 2 return circuit between the sensor connector and the ECM connector.
Is the resistance less than 10 ohms?
Yes
Go To 20
No
Repair the open return circuit.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
20. SIGNAL CIRCUIT SHORTED TO SUPPLY CIRCUIT
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 signal circuit in the sensor connector and the APPS 2 supply circuit in the sensor connector.
Is the resistance greater than 100 K ohms?
Yes
Go To 21
No
Repair the signal circuit shorted to the supply.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
21. RETURN CIRCUIT SHORTED TO OTHER CIRCUITS
--------------------------------------------------------------------------------
Measure the resistance between the APPS 2 return circuit at the ECM connector and all other circuits in the ECM connector.
Yes
Go To 22
No
Repair the return circuit shorted to other circuits.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
22. ECM
--------------------------------------------------------------------------------
Reconnect the ECM connectors.
Reconnect the APPS connector.
Turn Ignition on, engine off.
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 POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
23. APPS
--------------------------------------------------------------------------------
Reconnect the APPS connector.
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 acceraaltor and is the voltage from APPS 1 twice as much as the voltage from APPS 2?
Yes
Refer to the INTERMITTENT CONDITION Symptom (Diagnostic Procedure). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
No
Replace the APPS.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL). (Refer to 9 - ENGINE - DIAGNOSIS AND TESTING)
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