Diagnostic Test

1) VERIFY DTC IS ACTIVE
NOTE: Ensure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.

With the scan tool, read active DTCs.

Is this DTC active?

Yes
1. Go to 2).
No
1. Refer to the Stored Lost Communication test procedure. Refer to DIAGNOSTIC CODE INDEX table.
2) CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
With the scan tool, read all 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
1. Diagnose and repair the DTC. Refer to DIAGNOSTIC CODE INDEX table for a complete list of the symptoms. Refer to appropriate Engine ELECTRICAL DIAGNOSTICS article for powertrain DTCs.
No
1. Go to 3).
3) VERIFY THAT THE ECM/PCM IS ACTIVE ON THE BUS
Turn the ignition on.

With the scan tool, select Network Diagnostics.

Verify that the ECM/PCM is active on the bus.

Is the ECM/PCM active on the bus?

Yes
1. Go to 4).
No
1. Refer to the NO RESPONSE test procedure. Refer to DIAGNOSTIC CODE INDEX table.
4) CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
With the scan tool, select Network Diagnostics.

Is there more than one module with active DTCs "Logged Against" the ECM/PCM?

Yes
1. Replace/update the ECM/PCM in accordance with the service information.
2. Perform the appropriate VERIFICATION TEST.
No
1. Replace/update the module that set this DTC in accordance with the service information.
2. Perform the appropriate VERIFICATION TEST.