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vipertech763
vipertech763, automotive technician
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Dodge: the Cummins motor, I have a trouble code of U1421, What

Resolved Question:

I have a 06 Dodge 2500 with the Cummins motor, I have a trouble code of U1421, What does it mean? Thanks
Submitted: 9 years ago.
Category: Dodge
Expert:  vipertech763 replied 9 years ago.

The code found is u1421 implausible ignition key off time recieved. This is not a common code. Here is the actual test for the code. Note: it requires the factory scanner to check it and the other control modules for any other possible codes:

U1421-IMPLAUSIBLE IGNITION KEY OFF TIME RECEIVED

For a complete wiring diagram Refer to Section 8W.

  • When Monitored:

    Ignition on.

  • Set Condition:

    The fuel volume message the ECM is receiving is implausible. The circuit is continuously monitored. One Trip fault.

Possible Causes
CAN B OPEN OR SHORTED
CLUSTER MODULE
FCM (TOTALLY INTEGRATED POWER MODULE)
ECM

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

 

Theory of Operation

The Totally Integrated Power Module (TIPM) isn't receiving a fuel volume signal over CAN B from the Cluster Module. The TIPM has to send the PCM a fuel volume signal over CAN C. The signal the TIPM sends over CAN C is implausible.

 

Diagnostic Test

1. ACTIVE DTC


Ignition on, engine not running.
With a scan tool read DTCs.

Is the DTC active at this time?

Yes

  • Go To 2


No

  • Refer to the INTERMITTENT CONDITION Diagnostic Procedure.
  • Perform the POWERTRAIN VERIFICATION TEST.



2. CAN B BUS HARDWARE DTCS ALSO ACTIVE


With a scan tool check for DTCs in the TIPM.

Are any CAN B Hardware related DTCs active at this time?

Yes

  • (Refer to 8 - ELECTRICAL/ELECTRONIC CONTROL MODULES - DIAGNOSIS AND TESTING) for the appropriate diagnostic procedures.
  • Perform BODY VERIFICATION TEST - VER 1.


No

  • Replace and program the Powertrain Control Module per Service Information.
  • Perform the POWERTRAIN VERIFICATION TEST.



It appears the issue will be the engine controller however it all depends if there are any other codes found. Let me know if you need more help or have more questions.

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