Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Test
- VERIFY THE DIAGNOSTIC TROUBLE CODE (DTC) IS ACTIVE NOTE: Make sure the IOD fuse is installed and battery voltage is between 10 and 16 volts before proceeding.
- Using the scan tool, read active DTCs.
Is this DTC active?
Yes
- Go to step 2
No
- Refer to Non-DTC Diagnostics/Communication - Diagnosis and Testing and perform the Stored Lost Communication DTCs diagnostic procedure.
- Using the scan tool, read active DTCs.
- CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
- Using 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
- Go to and perform the appropriate diagnostic procedure.
No
- Go to step 3
- Using the scan tool, read all active DTCs from all modules.
- VERIFY THAT THE FCM IS ACTIVE ON THE BUS
- Turn the ignition on.
- Using the scan tool, select Network Diagnostics.
- Verify that the FCM is active on the bus.
Is the FCM active on the bus?
Yes
- Go to step 4
No
- Refer to Non-DTC Diagnostics/Communication - Diagnosis and Testing and perform the No Response from FCM diagnostic procedure.
- CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
- Using the scan tool, select Network Diagnostics.
Is there more than one module with active DTCs "Logged Against" the FCM?
Yes
- Replace/update the Front Control Module in accordance with the Service Information.
- Perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure
No
- Replace/update the module that set this DTC in accordance with the Service Information
- Perform the appropriate verification test for the module being replaced. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Front Control (FCM) - Standard Procedure .
- Using the scan tool, select Network Diagnostics.
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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