1. Perform Diagnostic System Check - Vehicle before using the brake indicator symptom tables in order to verify that all of the following are true:
• There are no DTCs set.
• The control module(s) can communicate via the serial data link.
2. Perform the Brake System Vehicle Road Test before using the hydraulic brake symptom tables in order to duplicate the customer's concern.
3. Review the system operation in order to familiarize yourself with the system functions. Refer to the following:
• Brake Warning System Description and Operation
• Hydraulic Brake System Description and Operation
• Brake Assist System Description and Operation
• Disc Brake System Description and Operation

• Inspect for aftermarket devices which could affect the operation of the brake warning system. Refer to Checking Aftermarket Accessories.
• Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections.

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

• Brake Warning Indicator Malfunction
• Brake Pulsation
• Brake System Noise
• Braking Action Uneven - Pulls to One Side
• Braking Action Uneven - Front to Rear
• Brake Pedal Excessive Travel
• Brake Pedal Excessive Effort
• Brakes Drag
• Brake System Slow Release
• Brake Fluid Loss