U1421

U1421-IMPLAUSIBLE IGNITION KEY OFF TIME RECEIVED

For a complete wiring diagram Consult Diagrams/Electrical

- 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 FCM.





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.Intermittent Condition

2. CHECKING FOR OTHER DTCS
With the scan tool, read other FCM DTCs.

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

Are there any ECM communication related DTC's in the FCM?

Yes

- Refer to the Symptom List and repair communication DTC's before continuing.
- Perform the ECM Verification Test Ver. 1. Powertrain Verification Test

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. Powertrain Verification Test

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. Powertrain Verification Test

5. FCM POWER AND GROUND CIRCUITS
Refer to the Wiring Information and verify proper battery supply, ignition switch supply and grounds at the FCM harness connectors.
Are the FCM power and grounds functioning properly?

Yes

- Replace the Front Control Module.
- Perform the ECM Verification Test Ver. 1. Powertrain Verification Test

No

- Repair power/ground circuit(s) as necessary.
- Perform the ECM Verification Test Ver. 1. Powertrain Verification Test