ABS Automated Bleed Procedure: Notes

Important:  In most circumstances a base brake bleed is all that is required for most component replacements (such as wheel cylinders, calipers, brake tubes, and master cylinder) except for BPMV replacement.

The following automated ABS bleed procedure is required when one of the following occur:

• Manual bleeding at the wheel cylinders does not achieve the desired pedal height or feel.
• Brake Pressure Modulator Valve replacement (BPMV).
• Extreme loss of brake fluid has occurred.
• Air ingestion is suspected.

If none of the above conditions apply use standard bleed procedures. Refer to HYDRAULIC BRAKE SYSTEM BLEEDING (MANUAL) or HYDRAULIC BRAKE SYSTEM BLEEDING (PRESSURE) in Hydraulic Brakes.

The auto bleed procedure is used on BOSH 5.3 equipped vehicles. This procedure uses a scan tool to cycle the system solenoid valves and run the pump in order to purge the air from the secondary circuits. These secondary circuits are normally closed off, and are only opened during system initialization at vehicle start up and during ABS operation. The automated bleed procedure opens these secondary circuits and allows any air trapped inside the BPMV to flow out toward the wheel cylinders or calipers where it can be purged out of the system.