U1421-IMPLAUSIBLE IGNITION KEY OFF TIME RECEIVED

For a complete wiring diagram Refer to Section 8W



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


No

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


No

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


No

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


No

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


No