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 DTC IS ACTIVE NOTE:
Make sure the battery voltage is between 10 and 16 volts before proceeding.
- With the scan tool, read active DTCs.
Is this DTC active?
Yes
- Go To 2.
No
- Refer to DIAGNOSIS AND TESTING and perform the Stored Lost Communication DTCs diagnostic procedure.
- With the scan tool, read active DTCs.
- CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS
- With the scan tool, read all active DTCs from all modules.NOTE:
Check for BCM configuration, CAN 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
- Refer to DTC INDEX and perform the appropriate diagnostic procedure.
No
- Go To 3.
- With the scan tool, read all active DTCs from all modules.
- VERIFY THE BCM IS ACTIVE ON THE BUS
- Turn the ignition on.
- With the scan tool, verify the BCM is active on the bus.
Is the BCM active on the bus?
Yes
- Go To 4.
No
- Refer to DIAGNOSIS AND TESTING and perform the No Response from BCM 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 BCM?
Yes
- Replace/update the BCM in accordance with the Service Information. Refer to MODULE, BODY CONTROL, REMOVAL .
- Refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
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 BCM.
- 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, refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
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 diagram/schematic as a guide, inspect the wiring for chafed, pierced, pinched, and partially broken wires and the wiring harness connectors for broken, bent, pushed out, and corroded terminals.
- Perform the appropriate verification test for the module. If there is no verification test for the associated module, refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
- 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, view the modules.
Do other CAN C BUS modules show Lost Communication with the remaining CAN C 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, refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
- With the scan tool, view the modules.
- CHECK THE CAN C BUS (+) CIRCUIT FOR A SHORT TO VOLTAGE
- Measure the voltage between the (D57) CAN C Bus (+) circuit and ground.
Is the voltage above 5.0 volts?
Yes
- Repair the short to voltage in the CAN C Bus (+) circuit. The short to voltage is present in one of the CAN C Bus circuits. Use the Star Connectors to isolate portions of the CAN C Bus in order to locate the concern.
- Refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
No
- Go To 9.
- Measure the voltage between the (D57) CAN C Bus (+) circuit and ground.
- CHECK THE CAN C BUS (-) CIRCUIT FOR A SHORT TO GROUND
- Turn the ignition off.
- Measure the resistance between ground and the (D58) CAN C Bus (-) circuit.
Is the resistance below 10k Ohms?
Yes
- Repair the short to ground in the CAN C Bus (-) circuit. The short to ground is present in one of the CAN C Bus circuits. Use the Star Connectors to isolate portions of the CAN C Bus in order to locate the concern.
- Refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
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, refer to STANDARD PROCEDURE and perform the BODY VERIFICATION TEST.
NO RELATED
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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.