Auto Bleed Procedure

COMPLETE BRAKE SYSTEM BLEED
The Auto Bleed Procedure is used to provide a complete brake system bleed; on Delco Bosch 5 (ABS) equipped vehicles. The procedure cycles the system valves and runs the pump to purge air from secondary circuits normally closed off during non-ABS/TCS mode operation and bleeding. Use this procedure where air is suspected in the secondary circuit or when replacing the Brake Pressure Modulator Valve (BPMV). To perform this procedure successfully, the following are required:
- Scan Tool.
- A pressure brake bleeder capable of producing at least 30 psi. with suitable adapters and filled with DOT-3 brake fluid, obtained from a sealed container.
- A hoist, or suitable stands to support vehicle.
- A bleeder bottle to receive vented brake fluid. The bottle should be constructed of unbreakable plastic, and should have a clear plastic hose sized to fit snugly on the bleeder valves. The hose should protrude into the bottle, with its end immersed in brake fluid.
- An assistant to pump the brake pedal during the procedure.
- Suitable safety attire, including safety glasses.

INSTRUCTIONS
1. Raise vehicle and support.
2. Remove all four wheels.
3. Inspect brake system for leaks or component damage. Correct all conditions found before starting procedure.
4. Assure vehicle battery is fully charged before beginning procedure.
5. Connect Scan Tool to DLC.
6. Turn Ignition to "RUN," do not start engine.
7. Establish communications with Scan Tool and select ABS/TCS system features.
8. Select "Special Functions"
9. Select "Auto Bleed Procedure."
10. Bleed base brake system as instructed in Manual bleeding. Manual Bleeding

11. Follow Scan Tool menu driven instructions until proper brake pedal height is achieved.

NOTE:
^ If any malfunctions are detected, the bleed procedure will be aborted.
^ If DTCs are present, the Scan Tool will display "DTCs PRESENT," or list the DTCs, depending on when the DTCs were set.
^ DTCs can be displayed or cleared as appropriate in the "Trouble Codes" mode. Testing and Inspection

^ If test is aborted but no DTCs are listed; diagnose the Brake system. Testing and Inspection

^ Correct all system malfunctions before attempting the bleed procedure again.
^ If a road test is required for diagnosis and brake pedal is "spongy," perform a conventional brake bleed, achieving a firm pedal before driving vehicle.

12. When Auto Bleed Procedure is complete, depress brake pedal. It should be high and firm.

NOTE:
^ If not, re-inspect brake system thoroughly for any conditions which could cause excess brake pedal travel. Diagnose the Brake system. Testing and Inspection

^ If brake system is OK, and excess pedal travel persists, repeat Auto Bleed Procedure.

13. Disconnect Scan Tool. Reinstall wheels and tires and lower vehicle.

NOTE:
^ Check brake fluid level in reservoir and fill if necessary. Road test vehicle, making several ABS and Traction Control stops in a suitable area. Brake pedal should remain high and firm after road test.