Brake Master Cylinder: Service and Repair

Service Information

Brake Master Cylinder and Servo Unit Removal and Installation

Removal

1. Vehicle - Lift

1. Raise the vehicle on a lift, and make sure it is securely supported.

2. Air Cleaner

1. Disconnect the intake air duct (A) from the air cleaner (B).

2. Remove the air cleaner.

3. Brake Fluid

1. Remove the reservoir cap.

2. Remove the brake fluid.

3. Reinstall the reservoir cap.

4. Brake Fluid - Removal

NOTICE:
Do not spill brake fluid on the vehicle; it may damage the paint. If brake fluid does contact the paint, wash it off immediately with water.

NOTE:
* Do not reuse the drained fluid. Use only new Honda DOT 3 Brake Fluid from an unopened container. Using a non-Honda brake fluid can cause corrosion and shorten the life of the system.
* When you turn the ignition switch to ON (II), the power unit may operate (you can hear the motor sound).
* Because the conventional brake system and the AHB system use the same brake fluid reservoir, fluid removal is necessary in order to purge old fluid from the AHB system.

1. Turn the ignition switch to LOCK (0).

2. Press the brake pedal 20 times to release the pressure in the accumulator.

3. Attach a length of clear drain tube (A) to the bleed screw (B) on the caliper or wheel cylinder.

4. Loosen the bleed screw, and pump the brake pedal until brake fluid stops coming out.

5. Tighten the bleed screw.

6. Attach a length of clear drain tube (A) to the bleed screw (B).

7. Loosen the bleed screw.

NOTE: Turn the bleed screw about 180 °.

8. Turn the ignition switch to ON (II).

NOTE: Do not operate the pump motor for more than 110 seconds or it may be damaged.

9. When the brake fluid is drained out, tighten the bleed screw.

NOTE: After draining the brake fluid from the servo unit and the power unit, the sound of the power unit function changes.

10. Turn the ignition switch to LOCK (0).

5. Brake Master Cylinder and Servo Unit Assembly

1. Remove the IMA system power cable clamps (A).

2. Remove the wire harness clip (B).

3. Remove the wire harness clamp (C).

4. Disconnect the connector (D).

5. Remove the reservoir tank (A).

6. Remove the wire harness clips (A).

7. Slide reservoir tank bracket (B) back to release it from the wire harness clamp (C).

8. Remove the reservoir tank bracket.

9. Remove the wire harness clamp (A).

10. Remove the wire harness clip (B).

11. Remove the wire harness clamps bracket (C).

12. Disconnect the brake lines (A) from the master cylinder (B).

13. Disconnect the suction hose (C) from the brake line (D).

14. Disconnect the connector (E).

15. Disconnect the brake line (A) from the servo unit (B).

16. Disconnect the connector (A) by pulling down the lock (B).

17. Remove the brake lines (A) from the clamp (B).

18. Remove the lock pin (A) and the clevis pin (B).

19. Disconnect the yoke (C) from the brake pedal.

20. Remove the servo unit mounting nuts (D).

21. Remove the servo unit (A) with master cylinder.

NOTE: Be careful not to bend or damage the brake lines.

22. Remove the servo unit gasket (B).

6. Brake Subreservoir

1. Remove the subreservoir (A).

2. Remove the reservoir grommets (B).

7. Brake Master Cylinder

1. Separate the master cylinder (A) from the servo unit (B).

Installation

1. Brake Master Cylinder Assembly

1. Install the master cylinder (A).

NOTE:
* Coat the new O-ring (B) with the Shin-Etsu silicone grease (P/N 08798-9013).
* Make sure not to get any silicone grease on the terminal part of the connectors and switches, especially if you have silicone grease on your hands or gloves.

2. Brake Subreservoir

1. Install the new reservoir grommets (A).

NOTE:
* Coat the new grommets with the Shin-Etsu silicone grease (P/N 08798-9013).
* Make sure not to get any silicone grease on the terminal part of the connectors and switches, especially if you have silicone grease on your hands or gloves.

2. Install the subreservoir (B).

3. If the suction hose (A) from the subreservoir (B) was removed, install the hose.

NOTE: Position the clamp (C) as shown.

4. If the reservoir tank hose was disconnected, install the reservoir tank (A) and the reservoir tank hose (B) to the subreservoir (C).

NOTE: Align the "^" mark (D) on the reservoir tank and subreservoir with the paint mark (E) on the hose.

3. Brake Master Cylinder and Servo Unit Assembly

1. Install the servo unit (A) with master cylinder.

NOTE:
* Be careful not to bend or damage the brake lines.
* Use a new servo unit gasket (B).

2. Install the servo unit mounting nuts (A).

3. Connect the yoke (B) to the brake pedal.

4. Install the lock pin (C) and the clevis pin (D).

5. Install the brake lines (A) to the clamp (B).

6. Connect the connector (A) by pushing up the lock (B).

7. Connect the brake line (A) to the servo unit (B).

8. Connect the connector (A).

9. Connect the suction hose (B) to the brake line (C).

10. Connect the brake lines (D) to the master cylinder (E).

11. Install the wire harness clamps bracket (A).

12. Install the wire harness clip (B).

13. Install the wire harness clamp (C).

14. Install the reservoir tank bracket (A) by sliding it over the wire harness clamp (B).

15. Install the wire harness clips (C).

16. Install the reservoir tank (A).

17. Connect the connector (A).

18. Install the wire harness clamp (B).

19. Install the wire harness clip (C).

20. Install the IMA system power cable clamps (D).

4. Brake System - Bleeding

NOTICE:
Do not spill brake fluid on the vehicle; it may damage the paint. If brake fluid does contact the paint, wash it off immediately with water.

NOTE:
* Do not reuse the drained fluid. Use only new Honda DOT 3 Brake Fluid from an unopened container. Using a non-Honda brake fluid can cause corrosion and shorten the life of the system.
* Make sure no dirt or other foreign matter gets in the brake fluid.
* The brake fluid reservoir tank must be at least 1/2 full at the start of the bleeding procedure and checked after bleeding each brake caliper or wheel cylinder. Add fluid as required.
* Turn the ignition switch to LOCK (0), while doing this procedure.
* There are three different methods used for bleeding brake systems. The method shown here is the preferred manual method for removing the air from the system. For pressure or vacuum bleeding, refer to tool manufacturer's instructions included with the tool.

1. Turn the ignition switch to LOCK (0).

2. Press the brake pedal several times until it becomes a hard brake pedal to release the pressure in the accumulator.

3. Make sure the brake fluid level in the reservoir tank (A) is at the middle of the tank line (B).

4. Start the bleeding at the driver's side of the front brake system.

NOTE: Bleed the calipers in the sequence shown.

Front

Rear

5. Attach a length of clear drain tube (A) to the bleed screw (B).

6. Submerge the other end of the drain tube into a clear plastic catch bottle of brake fluid (C).

7. Have an assistant slowly pump the brake pedal several times then apply steady continuous pressure.

8. Loosen the bleed screw slowly to bleed the fluid into the plastic catch bottle. The brake pedal will travel toward the floor as the fluid is bled from the system.

9. When the brake pedal reaches the floor, have the assistant hold the pedal in that position, then tighten the bleed screw. The brake pedal can now be released.

10. Check and refill the master cylinder reservoir tank to the middle of level line. Be sure to reinstall the master cylinder reservoir cap.

11. Repeat steps 7 thru 10 until the brake fluid in the clear drain tube appears fresh and there are no air bubbles in the fluid.

12. Repeat this procedure for each brake in the bleeding sequence.

13. Inspect the brake fluid level.

5. Servo Unit and Power Unit Brake System - Bleeding

2. Attach a length of clear drain tube (A) to the bleed screw (B).

3. Loosen the bleed screw.

4. Add the brake fluid to the reservoir tank, and turn the ignition switch to ON (II).

NOTE: Do not operate the pump motor for more than 110 seconds or it may be damaged.

5. Make sure the brake fluid is discharged from the bleed screw to allow air to escape from the system, then tighten the bleed screw securely.

6. Turn the ignition switch to LOCK (0).

7. Add the brake fluid in the reservoir tank, and keep it at the middle of the tank line.

8. Turn the ignition switch to ON (II).

9. Wait several seconds until the AHB indicator and/or brake system indicator goes off.

10. Turn the ignition switch to LOCK (0).

11. Press the brake pedal 20 times.

12. Wait about 5 minutes.

13. Repeat step 9 to step 12 two times.

14. Make sure the bleed screw is tightened.

15. Inspect the brake fluid level.

16. Check the brake pedal stroke.

17. Clear the DTC with the HDS, if necessary.

6. Brake Drag - Check

1. Spin the wheels to check for brake drag.

7. Air Cleaner

1. Install the air cleaner (A).

2. Connect the intake air duct (B) to the air cleaner.

8. Brake Pedal Height - Inspection

1. Inspect the brake pedal height. Adjustments

9. HDS DLC - Connection

1. Connect the HDS to the data link connector (DLC) (A) located under the driver's side of the dashboard.

2. Turn the ignition switch to ON (II).

3. Make sure the HDS communicates with vehicle. If it does not communicate, go to the DLC circuit troubleshooting.

10. Advanced Hydraulic Booster Memorizing 0 (Zero) Position

1. Clear the DTC(s) by following the screen prompts on the HDS.

2. Turn the ignition switch to LOCK (0), then turn it to ON (II) again.

3. Check for DTCs and make sure no DTC is indicated.

4. Memorize the 0 (zero) position of the brake pedal stroke sensor and the servo unit by following the screen prompts on the HDS.

NOTE:
* See the HDS Help menu for specific instructions.
* If the memorization process does not work, replace the servo unit.

5. Turn the ignition switch to LOCK (0).