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
- CHECK FOR AN ACTIVE DTC
- With the scan tool, read Body Control Module (BCM) DTCs and record on the repair order.
Is the DTC active?
Yes
- Go To 2
No
- Refer to STORED LOST COMMUNICATION DTCS and perform the STORED LOST COMMUNICATION DTCS diagnostic procedure.
- With the scan tool, read Body Control Module (BCM) DTCs and record on the repair order.
- CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
- With the scan tool, read active DTCs from all modules.NOTE:
Check for BCM configuration, Controller Area Network (CAN) IHS Bus 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 DIAGNOSTIC CODE INDEX and perform the appropriate diagnostic procedure.
No
- Go To 3
- With the scan tool, read active DTCs from all modules.
- VERIFY THE VEHICLE SYSTEM INTERFACE MODULE (VSIM) IS ACTIVE ON THE BUS
- Turn the ignition on.
- With the scan tool, verify the VSIM is active on the bus.
Is the VSIM active on the bus?
Yes
- Go To 4
No
- Refer to DIAGNOSIS AND TESTING and perform the NO RESPONSE FROM VSIM (VEHICLE SYSTEM INTERFACE MODULE) diagnostic procedure.
- CHECK FOR ADDITIONAL COMMUNICATION RELATED DTCS
- With the scan tool, read all the DTCs.
Is there more than one module with active DTCs "Logged Against" the VSIM?
Yes
- Replace/update the Vehicle System Interface Module (VSIM). Refer to MODULE, VEHICLE SYSTEM INTERFACE, REMOVAL .
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 5
- With the scan tool, read all the DTCs.
- CLEAR DTC IN MODULE SETTING FAULT
- With the scan tool, select the module setting the DTC against the VSIM.
- Clear active DTCs.
Is this DTC still active?
Yes
- 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. Refer to STANDARD PROCEDURE .
No
- Go To 6
- CYCLE IGNITION
- Cycle the ignition from RUN to OFF three times ending with the key in the RUN position.
Does this DTC become active?
Yes
- Go To 7
No
- The condition is not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
- Perform the appropriate verification test for the module. If there is no verification test for the associated module perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
- Cycle the ignition from RUN to OFF three times ending with the key in the RUN position.
- CHECK FOR ADDITIONAL LOST COMMUNICATION FAULTS
- With the scan tool, read the DTCs.
Does the BCM and other CAN IHS BUS modules show Lost Communication with the remaining CAN IHS BUS modules?
Yes
- Go To 8
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. Refer to STANDARD PROCEDURE .
- With the scan tool, read the DTCs.
- CHECK THE (D397) CAN IHS BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE
- Measure the voltage between the (D397) CAN IHS Bus (+) circuit and ground at the Data Link Connector (DLC).
Is the voltage above 5.0 volts?
Yes
- Repair the short to voltage in the (D397) CAN IHS Bus (+) circuit. The short to voltage is present in one of the CAN IHS Bus (+) circuits. Use the Star Connectors to isolate portions of the CAN IHS Bus (+) in order to locate the concern.
- Perform the BODY VERIFICATION TEST. Refer to STANDARD PROCEDURE .
No
- Go To 9
- Measure the voltage between the (D397) CAN IHS Bus (+) circuit and ground at the Data Link Connector (DLC).
- CHECK THE (D396) CAN IHS BUS (-) CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Check for continuity between ground and the (D396) CAN IHS Bus (-) circuit at the DLC.
Is there continuity between ground and the (D396) CAN IHS Bus (-) circuit?
Yes
- Repair the short to ground in the (D396) CAN IHS Bus (-) circuit. The short to ground is present in one of the CAN IHS Bus (-) circuits. Use the Star Connectors to isolate portions of the CAN IHS Bus (-) in order to locate the concern.
- Perform the BODY VERIFICATION TEST. Refer to 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. Refer to STANDARD PROCEDURE .
Use the Manual With the Right Hardware
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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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