Front Control Module (FCM)

U0164-LOST COMMUNICATION WITH HVAC CONTROL MODULE







- When Monitored:
With the ignition on.

Battery voltage between 10 and 16 volts.

IOD fuse installed.

Front Control Module (FCM) is configured correctly.

- Set Condition:
Bus messages not received from the A/C Heater Control (HVAC) for approximately 2 to 5 seconds.





1. VERIFY THE DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE

NOTE: Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.

1. With the scan tool, read active DTCs.

Is this DTC active?

Yes

- Go To 2

No

- Refer to the Stored Lost Communication test procedure. Stored Lost Communication DTCs

2. CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
1. With the scan tool, read active DTCs from all modules.

NOTE: Check for FCM configuration, CAN B or C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTCs.

Does the scan tool display any active DTCs to the conditions listed above?

Yes

- Go to and perform the appropriate diagnostic procedure.

No

- Go To 3

3. VERIFY THAT THE HVAC IS ACTIVE ON THE BUS
1. Turn the ignition on.
2. With the scan tool, select Network View and select Advanced.
3. Verify that the HVAC is active on the bus.

Is the HVAC active on the bus?

Yes

- Go To 4

No

- Refer to the No Response test procedure. Communications - Verbose Codes

4. CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
1. With the scan tool, select Network View and select Advanced.

Is there more than one module with active DTCs "Logged Against" the HVAC?

Yes

- Replace/update the A/C Heater Control.
- Perform the BODY VERIFICATION TEST. Body Verification Test

No

- Replace/update the module that set the DTC
- Perform the appropriate VERIFICATION TEST. Verification Tests