Here’s the brake bleeding procedure when the master cylinder has been removed, reinstalled, or replaced.
- Connect a scan tool to the vehicle.
- Start the engine and allow it to idle.
- Depress the brake pedal firmly and maintain steady pressure on the pedal.
- Using the scan tool, begin the automated bleed procedure.
- Follow the instructions on the scan tool to complete the automated bleed procedure. Release the brake pedal between each test sequence.
- Turn the ignition OFF and remove the scan tool from the vehicle.
- Fill the brake master cylinder reservoir to the maximum-fill level with GM approved brake fluid from a clean, sealed brake fluid container.
- Bleed the hydraulic brake system.
- With the ignition OFF, apply the brakes 3–5 times, or until the brake pedal becomes firm, in order to deplete the brake booster power reserve.
- Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
- If the brake pedal feels spongy, repeat the automated bleeding procedure.
- If the brake pedal still feels spongy after repeating the automated bleeding procedure inspect the brake system for external leaks.
- Turn the ignition key ON, with the engine OFF; check to see if the brake system warning lamp remains illuminated.
- If the brake system warning lamp remains illuminated, Do not allow the vehicle to be driven until it is diagnosed and repaired.
- Drive the vehicle to exceed 8 mph/ 13 km to allow ABS initialization to occur. Observe brake pedal feel.
- If the brake pedal feels spongy, repeat the automated bleeding procedure until a firm brake pedal is obtained.
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