U1421 Jeep OBD Code Diagnostic Procedure

U1421 U1421 Jeep OBD Code

IMPLAUSIBLE IGNITION KEY OFF TIME RECEIVED

For a complete wiring diagram Refer to Section 8W

  • When Monitored:

At ignition on.

  • Set Condition:The ECM detects a problem when comparing the current ECT Sensor input to the ECT Sensor input at the last ECM power down and the amount of time that has elapsed based on an internal timer in the TIPM.
Possible Causes
INTERMITTENT CONDITION
IGNITION SWITCH
TIPM POWERS AND GROUNDS
TOTALLY INTEGRATED POWER MODULE (TIPM)
ENGINE COOLANT TEMPERATURE SENSOR

Diagnostic Test

1. CHECK FOR ACTIVE DTC

NOTE:
If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed
on the scan tool at the same time the DTC is displayed.

NOTE:
Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.

  • Turn the ignition on.
  • With the scan tool, erase ECM DTCs.
  • Perform several ignition cycles, turning the ignition off for at least 10 seconds between each ignition cycle.
  • Monitor the scan tool for ECM DTCs.

Did this DTC set again?

Yes

  • Go To 2

No

  • Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.

(Refer to 9 – ENGINE – DIAGNOSIS
AND TESTING)


2. CHECKING FOR OTHER DTCS

With the scan tool, read other TIPM DTCs.

NOTE:
Any ECM communication related DTC’s in the TIPM must be diagnosed and corrected before continuing to diagnose this DTC.

Are there any ECM communication related DTC’s in the TIPM?

Yes

  • Refer to the Symptom List and repair communication DTC’s before continuing.

 

  • Perform the ECM Verification Test Ver. 1.(Refer to 9 – ENGINE – STANDARD PROCEDURE)

 

No

  • Go To 3


3. CHECKING THE ECT SENSOR

Refer to the symptom Checking the ECT Sensor and verify proper ECT Sensor operation.

Is the ECT Sensor operating correctly?

Yes

  • Go To 4

No

  • Repair the (K344) ASD Relay Output circuit for an open.

 

  • Perform the ECM Verification Test Ver. 1.(Refer to 9 – ENGINE – STANDARD PROCEDURE)

 


4. IGNITION SWITCH

Refer to the Wiring Information and verify proper Ignition Switch operation.

Turn the ignition key to each position and verify correct voltage output at each ignition switch harness connector cavity.

Is the Ignition Switch operating properly?

Yes

  • Go To 5

No

  • Repair or replace Ignition Switch, wiring or connectors as necessary.

 

  • Perform the ECM Verification Test Ver. 1.(Refer to 9 – ENGINE – STANDARD PROCEDURE)

 


5. TIPM POWER AND GROUND CIRCUITS

Refer to the Wiring Information and verify proper battery supply, ignition switch supply and grounds at the TIPM harness connectors.

Are the TIPM power and grounds functioning properly?

Yes

  • Replace the Totally Integrated Power Module in accordance with the Service Information.

 

  • Perform the ECM Verification Test Ver. 1.(Refer to 9 – ENGINE – STANDARD PROCEDURE)

 

No

  • Repair power/ground circuit(s) as necessary.

 

  • Perform the ECM Verification Test Ver. 1.(Refer to 9 – ENGINE – STANDARD PROCEDURE)

 

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