Brake Bleeding: Service and Repair
BRAKE FLUID LEVEL INSPECTION AND BLEEDINGCAUTION:
^ Use only brake fluid DOT3 DOT4. Never mix the specified brake fluid with other brake fluid, as it will significantly decrease braking performance.
^ Depress the brake pedal slowly. If the brake pedal is pressed too quickly, the pump motor will activate frequently and a large volume of high-pressure brake fluid may flow from the brake caliper quickly, depleting the HBB reservoir contents and possibly introducing air into the HBB system.
^ Depending upon the quantity of brake fluid in the reservoir, if the brake pedal is pressed with the reservoir cap removed, the brake fluid in the reservoir may overflow.
^ Use suitable protection to prevent brake fluid from contacting underhood components and body nai nt.
HBB System Bleeding
WARNING: The HBB system bleeding must be done in the following cases.
^ If brake fluid is drained after removing or installing the HBB
^ If there is excessive brake fluid loss during normal brake system bleeding
^ if you suspect that air has entered the HBB system
NOTE: The HBB brake system bleeding procedure requires two persons working together. HBB system bleeding must be done in the following order:
CAUTION
^ Keep the brake fluid reservoir level just above the "MIN" line. Monitor the fluid level during this procedure to ensure the fluid does not reach below the "MIN" line, to prevent air from entering the system.
^ If a large quantity of brake fluid is drained during the bleeding procedure, the accumulator pressure will decrease abnormally. Do not bleed more than 0.1 dm3 (0.11 quart) from each wheel at a time.
^ Confirm that the pump motor stops after each air-bleeding step. If not, proceed to the troubleshooting the HBB System section.
NOTE: The buzzer may sound during this procedure due to low pressure in the system. The buzzer will stop when normal HBB pressure is restored.
Required Special Tool:
^ MB991502: Scan Tool (MUT-II)
1. Fill the front brake system with brake fluid as follows (RH first, LH second):
1) Attach a clear hose to the RH caliper bleeder valve. This helps to monitor air/fluid flow.
2) Be sure the fluid level is between the "MIN" and "MAX" lines.
3) Turn the ignition switch to the "LOCK" (OFF) position. Pump the brake pedal 3 - 4 times and hold it depressed.
4) Open the RH caliper bleeder valve 1/4 turn.
5) With the bleeder valve still open, pump the brake pedal repeatedly to fill the line with fluid until no obvious air bubbles are seen. When no more obvious air bubbles are seen, and while the brake pedal is still being pumped, close the bleeder valve.
6) Repeat steps (1) - (5) for the LH caliper.
7) Release the brake pedal when both sides are filled.
2. Fill the pump motor as follows:
1) Turn the ignition switch to the "ON" position to operate the pump motor.
a. If the pump motor operates normally (normal operation sound), go to step 3.
b. If the pump motor operation sound is dry and high pitched, depress the brake pedal 3 or 4 times to introduce fluid into the pump motor. Then go to step 3.
3. Fill the accumulator system with brake fluid as follows:
1) Wait for the pump motor to stop from step 2.
2) Depress the brake pedal slowly 3 or 4 times with the ignition switch at the "ON" position. Observe the condition of the brake fluid in the reservoir.
a. If the fluid is cloudy, leave it for 2 or 3 minutes until it becomes clear.
b. Repeat the above procedure (a) until no bubbles appear while pumping the brake pedal.
NOTE: OK to fill the reservoir to the "MAX" line during this process. Brake fluid level around the "MIN" line may cause bubbles to appear from the jet flow of brake fluid while pumping the brake pedal.
4. Fill the rear brake system with brake fluid as follows (RH first, LH second):
CAUTION:
^ If a large quantity of brake fluid is drained during the bleeding procedure, the accumulator pressure will decrease abnormally. Do not bleed more than 0.1 dm3 (0.11 quart) from each wheel at a time.
^ Confirm that the pump motor stops after each air-bleeding step.
NOTE: A high-pressure hydraulic noise (hissing) is normal during this procedure.
1) Attach a clear hose to the RH caliper bleeder valve. This helps to monitor air/fluid flow.
2) Be sure the fluid level is between the "MIN" and "MAX" lines.
3) Turn the ignition switch to the "LOCK" (OFF) position. Pump the brake pedal 3 - 4 times and hold it depressed.
4) Open the RH caliper bleeder valve 1/4 turn.
5) With the bleeder valve still open, pump the brake pedal repeatedly to fill the line with fluid until no obvious air bubbles are seen. When no more obvious air bubbles are seen, and while the brake pedal is still being pumped, close the bleeder valve.
6) Repeat steps (1) - (5) for the LH caliper.
7) Release the brake pedal when both sides are filled.
5. Supply brake fluid into the power supply system as follows:
CAUTION: Keep the brake fluid reservoir level just above the "MIN" line at this time. Monitor the fluid level during this procedure to ensure it does not reach below the "MIN" line.
1) To release the pressure in the HBB power supply system, turn the ignition switch to the "LOCK" (OFF) position and depress the brake pedal repeatedly until its depressing force suddenly feels heavy (no pedal travel).
2) Turn the ignition switch to the "ON" position and at the same time quickly depress the brake pedal approximately 20 times. Then confirm that the pump motor has stopped. This can take up to 2 minutes.
3) Turn the ignition switch to the "LOCK" (OFF) position and depress the brake pedal repeatedly until its depressing force suddenly feels heavy (no pedal travel).
4) Turn the ignition switch to the "ON" position to operate the pump motor. Confirm that the pump motor stops within 25 seconds. If the pump motor does not stop, repeat steps (1) through (3) above.
6. Supply fluid into the ABS system as follows:
CAUTION: When connecting or disconnecting the scan tool, ensure that the ignition switch is at the "LOCK" (OFF) position.
1) urn the ignition switch to the "LOCK" (OFF) position and connect scan tool MB991502 to the data link connector.
2) Turn the ignition switch to the "ON" position. Select from scan tool menu screen as follows: [SYSTEM SELECT - ABS - ACTUATOR TEST - AIR BLEED]
3) Depress and hold the brake pedal.
4) Activate the actuator test [AIR BLEED (1)]. When the scan tool flashes confirmation that the AIR BLEED (1) operation is completed, proceed with AIR BLEED (2).
5) epress and hold the brake pedal.
6) Select and activate [AIR BLEED (2)] on the scan tool screen. When the scan tool flashes confirmation that the AIR BLEED (2) operation is completed, go to step 7.
7. Bleed the rear brake system as follows (RH first, LH second):
CAUTION:
^ Keep the brake fluid reservoir level just above the "MIN" line at this time. Monitor the fluid level during this procedure to ensure it does not reach below the "MIN" line.
^ If a large quantity of brake fluid is drained during the bleeding procedure, the accumulator pressure will decrease abnormally. Do not bleed more than 0.1 dm3 (0.11 quart) from each wheel at a time.
^ Confirm that the pump motor stops after each air-bleeding step.
1) Attach the clear hose to the RH caliper to monitor air/fluid flow.
2) Turn the ignition switch to the "ON" position.
3) Open bleeder valve 1/4 turn.
4) With the bleeder valve open, pump the brake pedal 3 times and hold.
5) Close the bleeder valve. Pump the brake pedal 3 times and hold.
7) Open the bleeder valve 1/8 turn briefly to allow any remaining air to escape, then close the bleeder valve.
8) Repeat steps (6) and (7) as many times as necessary to eliminate all air in the line.
9) Repeat steps (1) - (8) at the LH caliper.
8. Bleed the front brake system as follows (RH first, LH second):
CAUTION:
^ Keep the brake fluid reservoir level just above the "MIN" line at this time. Monitor the fluid level during this procedure to ensure it does not reach below the "MIN" line.
^ If a large quantity of brake fluid is drained during the bleeding procedure, the accumulator pressure will decrease abnormally. Do not bleed more than 0.1 dm3 (0.11 quart) from each wheel at a time.
^ Confirm that the pump motor stops after each air-bleeding step.
1) Attach the clear hose to the RH caliper to monitor air/fluid flow.
2) Turn the ignition switch to the "ON" position.
3) Open bleeder valve 1/4 turn.
4) With the bleeder valve open, pump the brake pedal 3 times and hold.
5) Close the bleeder valve. Pump the brake pedal 3 times and hold.
7) Open the bleeder valve 1/8 turn briefly to allow any remaining air to escape, then close the bleeder valve.
8) Repeat steps (6) and (7) as many times as necessary to eliminate all air in the line. Repeat steps (1) - (8) at the LH caliper.
9. Adjust the brake fluid level as follows:
1) Turn the ignition switch to the "LOCK" (OFF) position.
2) Depress the brake pedal repeatedly (up to 40 times or more) until its depressing force suddenly feels very heavy (no pedal travel).
3) Release the brake pedal.
4) Adjust the brake fluid level between the "MIN" and "MAX" lines on the reservoir.
Normal Brake System Air Bleeding
If the brake fluid level in the HBB reservoir is between the "MIN" and "MAX" lines after any brake servicing at the wheels (such as calipers, rotors, etc.), perform the following steps:
1. Bleed the rear brake system as follows (RH first, LH second):
CAUTION:
^ Keep the brake fluid reservoir level just above the "MIN" line at this time. Monitor the fluid level during this procedure to ensure it does not reach below the "MIN" line.
^ If a large quantity of brake fluid is drained during the bleeding procedure, the accumulator pressure will decrease abnormally. Do not bleed more than 0.1 dm3 (0.11 quart) from each wheel at a time.
^ Confirm that the pump motor stops after each air-bleeding step.
1) Attach the clear hose to the RH caliper to monitor air/fluid flow.
2) Turn the ignition switch to the "ON" position.
3) Open bleeder valve 1/4 turn.
4) With the bleeder valve open, pump the brake pedal 3 times and hold.
5) Close the bleeder valve.
6) Pump the brake pedal 3 times and hold.
7) Open the bleeder valve 1/8 turn briefly to allow any remaining air to escape, then close the bleeder valve.
8) Repeat steps (6) and (7) as many times as necessary to eliminate all air in the line.
9) Repeat steps (1) - (8) at the LH caliper.
2. Bleed the front brake system as follows (RH first, LH second):
CAUTION:
^ Keep the brake fluid reservoir level just above the "MIN" line at this time. Monitor the fluid level during this procedure to ensure it does not reach below the "MIN" line.
^ If a large quantity of brake fluid is drained during the bleeding procedure, the accumulator pressure will decrease abnormally. Do not bleed more than 0.1 dm3 (0.11 quart) from each wheel at a time.
^ Confirm that the pump motor stops after each air-bleeding step.
1) Attach the clear hose to the RH caliper to monitor air/fluid flow.
2) Turn the ignition switch to the "ON" position.
3) Open bleeder valve 1/4 turn.
4) With the bleeder valve open, pump the brake pedal 3 times and hold.
5) Close the bleeder valve.
6) Pump the brake pedal 3 times and hold.
7) Open the bleeder valve 1/8 turn briefly to allow any remaining air to escape, then close the bleeder valve.
8) Repeat steps (6) and (7) as many times as necessary to eliminate all air in the line.
9) Repeat steps (1) - (8) at the LH caliper.
3. Adjust the brake fluid level as follows:
1) urn the ignition switch to the "LOCK" (OFF) position.
2) Depress the brake pedal repeatedly (up to 40 times or more) until its depressing force suddenly feels very heavy (no pedal travel).
3) Release the brake pedal.
4) Adjust the brake fluid level between the "MIN" and "MAX" lines on the reservoir.