Brake Bleeding: Service and Repair
BLEEDING SYSTEMTools Required
Scan Tool
NOTICE: Prior to bleeding the brakes, the front and rear displacement cylinder pistons must be returned to the top-most (home) position. Using a scan tool, select the motor rehome function. You cannot perform the motor rehome function if current diagnostic trouble codes (DTCs) are present. If DTCs are present, you must repair the vehicle and clear the DTCs.
MOTOR REHOME FUNCTION
Tools Required
Scan Tool
The motor rehome function initiates from the scan tool main ABS VI screen. The motor rehome function should always be used prior to bleeding the brake system to eliminate any trapped air within the hydraulic modulator cylinders. It accomplishes this by returning the hydraulic modulator pistons to their home positions and forcing any trapped air toward the bleeder valves where it can easily be bled out.
If you do not have a scan tool available to command a motor rehome, follow the procedure below:
1. Raise and suitably support the front end of the vehicle so that the drive wheels are off the ground.
2. Start the engine, engage the transaxle, and run the vehicle above 5 km/h (3 mph) for at least 10 seconds.
3. Observe the ABS indicator. Make sure that the indicator goes out after approximately 3 seconds.
- If the ABS indicator remains illuminated, use a scan tool to diagnose the malfunction.
- If the ABS indicator goes out and stays off, stop the engine and repeat steps 2 and 3 one more time.
CAUTION: Brake fluid may irritate eyes and skin. In case of contact, take the following actions:
- Eye contact - rinse thoroughly with water.
- Skin contact - wash with soap and water.
- Ingestion - consult a physician immediately.
Important: In the following procedure, use a suitable container and/or shop cloths to catch brake fluid and prevent it from contacting any painted surfaces, wiring, cables, or electrical connectors.
4. Clean the master cylinder reservoir and the surrounding area.
5. Remove the master cylinder reservoir cap.
NOTICE: Do not use fluid from an open container that may be contaminated with water.
6. Inspect the brake fluid level. Add clean DOT 3, or equivalent, hydraulic brake fluid, if needed.
7. Install the master cylinder reservoir cap.
8. Bleed the hydraulic modulator:
8.1 Attach a clear plastic bleeder hose to the right side bleeder valve on the hydraulic modulator. Submerge the other end of the bleeder hose in a clean container partially filled with brake fluid.
8.2 Slowly open the right-side bleeder valve 1/2 to 3/4 turn.
8.3 Have an assistant press the brake pedal and hold it down until the brake fluid begins to flow.
8.4 Close the bleeder valve and release the brake pedal. Repeat steps 8.2 and 8.3 until no air bubbles are present.
Tighten
Tighten the bleeder valve to 9 Nm (80 inch lbs.).
8.5 Repeat the procedure for the left-side bleeder valve.
Important: Once fluid flows from both hydraulic modulator bleeder valves, the hydraulic modulator is sufficiently full of brake fluid. However, it may not be completely purged of air. At this point, move to the wheel cylinders and the calipers and bleed them. This ensures that the lowest points in the system are completely free of air. Then the hydraulic modulator can be purged of any remaining air.
9. Bleed the system according to one of the bleeding procedures below.
10. Bleed the hydraulic modulator.
10.1 Attach a clear plastic bleeder hose to the right-side bleeder valve on the hydraulic modulator. Submerge the other end of the bleeder hose in a clean container partially filled with brake fluid.
10.2 Slowly open the right-side bleeder valve 1/2 to 3/4 turn.
10.3 Have an assistant press the brake pedal and hold it down until the brake fluid begins to flow.
10.4 Close the bleeder valve and have the assistant release the brake pedal. Repeat Steps 10.2 and 10.3 until no air bubbles are present.
Tighten
Tighten the bleeder valve to 9 Nm (80 inch lbs.),
10.5 Repeat the procedure for the left-side bleeder valve.
11. Remove the master cylinder reservoir cap.
12. Inspect the brake fluid level; add clean DOT 3, or equivalent, hydraulic brake fluid, if needed.
13. Install the master cylinder reservoir cap.
14. Inspect the brakes.
- With the ignition switch ON, press the brake pedal with moderate force and hold it in position. Note pedal travel and feel.
- If the pedal feels firm and constant, and pedal travel is not excessive, start the engine. With the engine running, re-check the pedal travel. If it is still firm and pedal travel is not excessive, proceed with step 15.
- If the pedal feels soft or has excessive travel whether initially or after the engine starts, using the scan tool, release then apply the motors 3 times and cycle the solenoids 10 times. Be sure to apply the motors to ensure that the pistons are in the home position. Repeat the bleeding procedure.
15. Road test the vehicle. Make several normal (non ABS) stops from a moderate speed to ensure proper brake system function.
BLEEDING PROCEDURES
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 braking 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 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.
11. Tighten the bleeder valve and replace the dust covers.
Tighten
Tighten the bleeder valve to 6 Nm (53 inch lbs.).
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, it must be bled before any wheel cylinder or caliper is bled. If the decision is made not to bleed the master cylinder, go to step 11.
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
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 air from the cylinder.
8. Tighten the brake line (as in step 5), and release the brake pedal slowly. Wait 15 seconds before proceeding to the next step.
9. Repeat the sequence, including the 15-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 without the antilock braking system (ABS), the bleeding sequence is as follows: right rear, left front, left rear and right front. For vehicles with ABS, refer to Models With ABS Only for the correct sequence and bleeding procedure.
11. Attach a transparent tube over the bleeder 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. Loosen the bleeder screw to purge the air from the cylinder.
14. 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.
15. 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.
16. Tighten the bleeder valve and replace the dust cover.
Tighten
Tighten the bleeder valve to 6 Nm (53 inch lbs.).
17. Proceed to bleed the brakes following the appropriate sequence, beginning with step 11.
18. Check the brake pedal for sponginess. Repeat the entire bleeding procedure to correct this condition.