Diagnostic System Check
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2012 GMC Yukon XL, 2012 GMC Yukon, 2012 Chevrolet Tahoe, 2012 Chevrolet Suburban, and 2012 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
- VERIFY CUSTOMER CONCERN-Understand and validate the customer concern. Inspect the visible system components for obvious damage or conditions that may cause the concern.
- BULLETIN SEARCH-Check for related bulletins, recall/field actions and preliminary information.
- MECHANICAL CONCERNS-Verify the symptom is not exclusively a mechanical concern.
- If the symptom is exclusively a mechanical concern, refer to Symptoms - Vehicle .
- VEHICLE POWER UP VERIFICATION-Ignition ON, verify the vehicle powers up.
- If the vehicle does not power up, refer to Power Mode Mismatch .
- CONTROL MODULE COMMUNICATION and DTC CHECK-Using a scan tool, perform the Vehicle DTC Information function and verify at least one control module communicates with the scan tool. Record on the Repair Order the following information:
- Any control module that is not communicating.
- Any DTC, including symptom byte, and the control module that has set the DTC.
- If the scan tool does not communicate with any control module on the vehicle, refer to Data Link References .
- CONTROL MODULE INTERNAL PERFORMANCE FAULTS-Verify there are no current control module Internal Hardware Performance DTCs set.
- If any DTC of this type is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- CONTROL MODULE COMMUNICATION VERIFICATION-Verify the vehicle is built with any control module listed as not communicating, refer to Data Link References
. All control modules should be communicating, as equipped.
- If the scan tool does not communicate with one or more control modules refer to Data Link References .
- COMMUNICATION and POWERMODE FAULTS-Verify there are no current control module Power Mode or Communication DTCs set.
- If any DTC of this type is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- POWER MODE VERIFICATION-Driver door open, observe the scan tool Power Mode parameter while cycling the ignition switch through all the power modes. Verify the current Power Mode parameter matches the actual ignition switch positions.
- If the Power Mode parameter does not match the actual ignition switch positions, refer to Power Mode Mismatch .
- ENGINE CRANK and RUN VERIFICATION-Verify that the engine cranks and runs.
- If the engine does not crank, refer to Engine Does Not Crank .
- If the engine does not run, refer to Engine Cranks But Does Not Run .
- REMAINING DTC REVIEW-Verify there are no other DTCs set.
- If other DTCs are set, diagnose them in the order listed below. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .
- Voltage DTCs
- Programming, Setup, Configuration or Software Performance DTCs
- Component related DTCs
- System related DTCs
- Any remaining DTCs
- EMISSION RELATED INSPECTION/MAINTENANCE TESTING CONCERNS-If inspection and maintenance checks are required in your region, verify the customer concern is not related to inspection/maintenance testing.
- If the customer concern is related to inspection/maintenance testing, refer to Inspection/Maintenance System Check .
- SYMPTOM DIAGNOSIS-Diagnose any remaining customer concern. Refer to Symptoms - Vehicle .
NOTE:
Do not clear any DTCs unless instructed to do so by a diagnostic procedure. If any DTC is Powertrain related, select Capture Info to store DTC and Freeze Frame/Failure Records to the Scan Tool.
NOTE:
The engine may start during this test. Ensure the vehicle is out of gear and the parking brake is applied. Turn the engine OFF as soon as the crank power mode parameter has been observed.