Brake Bleeding: Service and Repair
BLEEDING SYSTEMReplacement modulators are shipped already filled and bled. In normal procedures requiring removal of the modulator, such as to replace the EBCM, air will not enter the modulator, and normal bleeding will be all that is needed.
If air enters the hydraulic modulator, or if an unfilled modulator is installed, use the brake bleeding program in the scan tool to bleed the modulator, Manual bleeding of the hydraulic modulator is not possible.
PRESSURE BLEEDING THE BRAKES
Notice: Pressure bleeding equipment must be of the diaphragm type. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture, oil, and other contaminants from entering the hydraulic system. Contamination could lead to deterioration of the braking components and loss of braking action.
1. Disconnect the master cylinder electrical connector.
2. Remove the master cylinder reservoir cap.
3. Connect the bleeder with the adapter to the master cylinder reservoir.
4. For vehicles with the Antilock Brake System (ABS), locate and remove the hydraulic modulator bleeder valves.
5. Charge the bleeder ball to 140 to 172 kPa (20 to 25 psi).
6. Connect the line to the adapter. Open the line valve.
7. Raise and suitably support the vehicle.
Important: The bleeding sequence is as follows: right rear, left front, left rear, and right front.
8. Attach the bleeder hose to the bleeder valve. Submerge the opposite end of the hose in a clean container partially filled with brake fluid.
9. Open the bleeder valve one-half to three-fourths of a turn and allow the fluid to flow until no air is seen in the fluid.
Notice: After the bleeding operation, the brake reservoir may be pressurized. While disconnecting the bleeder hose or the unthreaded adapter cap, cover the cap and the connection with a shop towel to protect painted surfaces from contact with the brake fluid.
10. Inspect the brake pedal for sponginess. Repeat the entire bleeding procedure to correct this condition.
MANUAL BLEEDING THE BRAKES
1. Remove the booster reserve by applying the brakes several times with the engine OFF until all the reserve is depleted.
Important: If the master cylinder is known or suspected to have air in the bore, then it must be bled before any wheel cylinder or caliper is bled.
2. Fill the master cylinder reservoir with brake fluid. Keep the master cylinder at least one-half full of fluid during the bleeding operation.
3. Disconnect the front brake line(s) at the master cylinder.
4. Allow the brake fluid to fill the master cylinder until it begins to flow from the front pipe connector port.
5. Connect the front brake line(s) to the master cylinder.
- Tighten the brake lines to 16 Nm (12 ft. lbs.).
6. Slowly push and hold the brake pedal one time.
7. Loosen the front brake line at the master cylinder to purge all air from the cylinder.
8. Tighten the brake line as in Step 5, and then release the brake pedal slowly. Wait 15 seconds before proceeding to the next step.
9. Repeat the sequence, including the 1 5-second wait, until all the air is removed from the master cylinder bore.
Notice: Care must be taken to prevent brake fluid from contacting any painted surface to prevent damage to the paint finish.
10. After all the air has been removed at the forward connection(s), bleed the master cylinder at the rear (cowl) connection(s) in the same manner as with the front connections.
Important: For vehicles equipped with a non-antilock braking system, non-ABS, the bleeding sequence is as follows: right rear, left front, left rear, and right front.
11. Attach a transparent tube over the valve. Allow the tube to hang submerged in brake fluid in a transparent container.
12. Slowly push and hold the brake pedal one time.
13. Remove the bleeder cap and loosen the bleeder screw to purge the air from the cylinder.
14. Tighten the bleeder screw.
- Tighten the bleeder screw to 9 Nm (80 inch lbs.).
15. Slowly release the brake pedal. Wait 15 seconds before proceeding with the next step.
Important: Rapid pumping of the brake pedal pushes the master cylinder secondary piston down the bore in a manner that makes it difficult to bleed the system.
16. Repeat the sequence, including the 15-second wait, until all the air is removed. It may be necessary to repeat the sequence 10 or more times to remove all the air.
17. Locate the front bleeder caps.
18. Proceed to bleed the front brakes following the appropriate sequence, beginning with Step 12.
19. Check the brake pedal for sponginess. Repeat the entire bleeding procedure to correct this condition.