Verify that none of the following preliminary inspections/tests reveal the cause of the vehicle concern before beginning diagnosis:
Ensure that the battery is fully charged.
Ensure that the battery cables are clean and tight.
Inspect for any open fuses.
Ensure that the grounds are clean, tight, and in the correct location.
Inspect the easily accessible systems or the visible system components for obvious damage or conditions that could cause the concern. This would include checking to ensure that all connections/connectors are fully seated and secured.
Inspect for aftermarket devices that could affect the operation of the system.
Inspect the master cylinder reservoir for the proper brake fluid level.
Search for applicable service bulletins.
Install the scan tool to the Data Link Connector (DLC).
Use the appropriate scan tool selections to obtain DTCs from the required modules.
Check for related trouble codes.
Repair as needed.