Hydraulic Brake System Bleeding
Hydraulic Brake System Bleeding (Two-mode Hybrid)
Special Tools
* J-29532-A - Brake Pressure Bleeder , or J-29532 - Diaphragm Pressure Bleeder , or equivalent
* J-35589-A - Brake Pressure Bleeder Adapter, or equivalent
Warning: Refer to Brake Fluid Irritant Warning (Brake Fluid Irritant Warning).
Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution (Vehicle Damage Warnings).
Caution: When adding fluid to the brake master cylinder reservoir, use only GM approved or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container. The use of any type of fluid other than the recommended type of brake fluid may cause contamination which could result in damage to the internal rubber seals and/or rubber linings of hydraulic brake system components.
1. Place the transmission in the PARK position.
2. Place a clean shop cloth beneath the brake master cylinder to prevent brake fluid spills.
Note: The ignition must be in the OFF position, without pausing at ACCESSORY, and without applying the brake pedal to ensure the brake modulator and high pressure accumulator (HPA) pressure relief occurs. This process will take approximately 1-3 minutes.
3. Turn the ignition to OFF, without pausing at ACCESSORY, and without applying the brake pedal.
Remove the ignition key.
4. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle (Service and Repair).
5. Remove the tire and wheel assemblies. Refer to Tire and Wheel Removal and Installation (Service and Repair).
6. Visually inspect the brake system for brake fluid leaks and damage. Refer to Symptoms - Hydraulic Brakes (Symptoms - Hydraulic Brakes).
Repair or replace components as necessary.
7. Lower the vehicle to a working height to bleed the hydraulic brake system.
8. If you have performed a brake master cylinder bench bleeding on this vehicle, or if you disconnected the brake pipes from the master cylinder, or from the brake pressure modulator valve (BPMV), you must perform the following steps to bleed air at the ports of the hydraulic brake component:
1. Ensure that the brake master cylinder reservoir is full to the maximum-fill level. If necessary add GM approved, or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
If removal of the reservoir cap and diaphragm is necessary, clean the outside of the reservoir on and around the cap prior to removal.
2. Clean the outside of the master cylinder reservoir on and around the cap prior to removal.
3. With the brake pipes installed securely to the affected hydraulic brake system component, loosen and separate one of the brake pipes from the port of the affected hydraulic brake system component.
4. Allow a small amount of brake fluid to gravity bleed from the open port of the affected hydraulic brake system component.
5. Reconnect the brake pipe to the affected hydraulic brake system component port and tighten securely.
6. Have an assistant slowly depress the brake pedal fully and maintain steady pressure on the pedal.
7. Loosen the same brake pipe to purge air from the open port of the affected hydraulic brake system component.
8. Tighten the brake pipe, then have the assistant slowly release the brake pedal.
9. Wait 15 seconds, then repeat steps 8.3-8.8 until all air is purged from the same port of the affected hydraulic brake system component.
10. With the brake pipe installed securely to the affected hydraulic brake system component, after all air has been purged from the first port of the affected hydraulic brake system component that was bled, loosen and separate the next brake pipe from the affected hydraulic brake system component, then repeat steps 8.3-8.8.
11. After completing the final affected hydraulic brake system component port bleeding procedure, ensure that each of the brake pipe-to-component fittings are properly tightened.
9. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved, or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
Clean the outside of the reservoir on and around the reservoir cap prior to removing the cap and diaphragm.
10. Install the J-35589-A - Brake Pressure Bleeder Adapter, or equivalent , to the brake master cylinder reservoir.
11. Inspect the brake fluid level in the J-29532-A - Brake Pressure Bleeder , or J-29532 - Diaphragm Pressure Bleeder , or equivalent.
12. Clean the outside of the J-29532-A or the J 29532 and add GM approved, or equivalent, brake fluid from a clean sealed brake fluid container, as necessary.
13. Connect the J-29532-A - Brake Pressure Bleeder , or J-29532 - Diaphragm Pressure Bleeder , or equivalent, to theJ-35589-A - Brake Pressure Bleeder Adapter, or equivalent.
14. Set the pressure regulator of the J-29532-A - Brake Pressure Bleeder , or charge the air tank of the J-29532 - Diaphragm Pressure Bleeder , to 200 kPa (30 psi).
15. Open the J-29532-A - Brake Pressure Bleeder , or J-29532 - Diaphragm Pressure Bleeder , or equivalent, fluid tank valve to allow pressurized brake fluid to enter the brake system.
16. Wait approximately 30 seconds, then inspect the entire hydraulic brake system in order to ensure there are no existing external brake fluid leaks.
Any brake fluid leaks identified require repair prior to completing this procedure.
17. Use the following sequence for bleeding the wheel hydraulic circuits:
* Right rear
* Left rear
* Right front
* Left front
18. Install a proper box-end wrench onto the appropriate wheel hydraulic circuit bleeder valve.
19. Secure a transparent bleeder hose to the bleeder valve.
20. Submerge the open end of the transparent hose into a transparent container partially filled with GM approved or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
21. Loosen the bleeder valve to purge air from the wheel hydraulic circuit. Allow fluid to flow for 30 seconds, or until air bubbles stop flowing from the bleeder, then tighten the bleeder valve.
22. With the first wheel hydraulic circuit bleeder valve tightened securely, repeat steps 18-21 for the remaining wheel hydraulic circuits in the proper sequence.
23. After completing the final wheel hydraulic circuit bleeding procedure, ensure that each of the 4 wheel hydraulic circuit bleeder valves are properly tightened.
24. Close the J-29532-A - Brake Pressure Bleeder , or J-29532 - Diaphragm Pressure Bleeder , or equivalent, fluid tank valve, then disconnect the J-29532-A - Brake Pressure Bleeder , or J-29532 - Diaphragm Pressure Bleeder , or equivalent, from the J-35589-A - Brake Pressure Bleeder Adapter, or equivalent.
25. Remove the J-35589-A - Brake Pressure Bleeder Adapter, or equivalent from the brake master cylinder reservoir.
26. Fill the brake master cylinder reservoir to the maximum-fill level with GM approved, or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
27. Slowly depress and release the brake pedal. Observe the feel of the brake pedal.
Note: If it is determined that air was introduced into the system upstream of the ABS modulator prior to servicing, the Antilock Brake System Automated Bleed (Service and Repair) must be performed.
28. If the brake pedal feels spongy perform the following steps:
1. Inspect the brake system for external leaks. Refer to Brake System External Leak Inspection (Component Tests and General Diagnostics).
2. Using a scan tool, perform the antilock brake system automated bleeding procedure to remove any air that may have been trapped in the brake pressure modulator valve (BPMV). Refer to Antilock Brake System Automated Bleed (Service and Repair).
29. Turn the ignition key ON, with the engine OFF. Check to see if the brake system warning lamp remains illuminated.
Note: If the brake system warning lamp remains illuminated, DO NOT allow the vehicle to be driven until it is diagnosed and repaired.
30. If the brake system warning lamp remains illuminated, refer to Symptoms - Hydraulic Brakes (Symptoms - Hydraulic Brakes).