Bleeding the hydraulic control unit (HCU) is required only when removing or installing the HCU or master cylinder, or opening the lines to the HCU.
Carrying out the System Bleed function drives trapped air from the HCU. Subsequent bleeding removes the air from the brake hydraulic system through the bleeder screws.
Adequate voltage to the HCU module is required during the anti-lock control portion of the system bleed.
Connect the WDS or equivalent Tester.
Access the SYSTEM BLEED FUNCTION. Go to the Tool Tab-Chassis-Braking-ABS Service Bleed and follow the directions on the diagnostic tool.
Manually bleed the brake hydraulic system.
Repeat the procedure carrying out a total of two diagnostic tool cycles and two manual bleed cycles.