Canada - ABS/TCS - Brake Actuator Squawk/Bark Noise
BulletinTSB2659
Issue Date
June 23, 2009
Title
SQUAWK/BARK TYPE NOISE FROM BRAKE ACTUATOR
Component
BRAKES
Models
'07-'09 LS460, LS600h
INTRODUCTION:
Small amounts of air in the brake system may cause a squawk or bark type noise from the brake actuator in some LS 460/460L and LS 600h vehicles. If present, this condition is most noticeable when the vehicle is not moving and the brake pedal is depressed, or when coming to an abrupt stop. Follow the procedures outlined in this bulletin to completely remove any residual air from the system that could contribute to this condition.
This procedure should also be followed anytime the brake actuator assembly is replaced.
Refer to the attached video link for an example of the squawk/bark noise condition:
LS Squawk/Bark Noise Example
APPLICABILITY:
WARRANTY INFORMATION:
REQUIRED TOOLS & EQUIPMENT:
REPAIR PROCEDURE OVERVIEW:
The brake bleed procedure consists of 5 main sections:
- Section 1: Zero Down Accumulator Pressure (Zero Down)
This procedure is used to release the pressure from the accumulator prior to bleeding the brakes (or replacing the brake actuator). Techstream is used for this procedure.
- Section 2: Disable Electronic Controlled Brakes (ECB Invalid)
This procedure, using Techstream, disables the ECB system temporarily to allow the front brakes to be bled manually. Using Techstream to disable brake control causes the master cylinder cut solenoid to turn OFF and the line from the master cylinder to front brake calipers to open, allowing manual bleeding of the front brakes.
- Section 3: Front Brake Bleed - Manual Process
This is a two-man process in which one technician pumps and holds the brake pedal, while another technician opens the right front bleeder screw to remove air from the system. The same procedure is repeated for the left front.
- Section 4: Rear Brake Bleed
- Right Rear Brake Line Air Bleed
During this procedure, Techstream opens the solenoid for the right rear brake line and then the accumulator pump runs during this process to push fluid and air out of the right rear caliper bleeder valve. During this process, the brake pedal is NOT applied - the accumulator pump will automatically pump fluid out of the right rear caliper bleeder valve. This process bleeds the red brake line (suction line from the accumulator to the actuator) and passes air out through the right rear caliper bleeder.
- Left Rear Brake Line Air Bleed
The left rear brake line is bled using a combination of the brake pedal being pressed-and held and the accumulator pump.
- Section 5: Reset Memory and Linear Valve Offset Calibration
The purpose of this step is to erase all previously memorized brake actuator linear valve calibration values and to re-calibrate the brake actuator linear valves after all brake bleeding procedures are finished. This procedure resets the memory of the skid control computer and then performs the Linear Valve Offset Learning Process. During the Linear Valve Offset Learning Process, the skid control computer memorizes the characteristics of the actuator linear solenoids.
REPAIR PROCEDURE:
Section 1: Zero Down Accumulator Pressure (Zero Down)
IMPORTANT
- When the actuator is replaced, there is no pressure in the accumulator and the Zero Down procedure is NOT necessary.
- If the actuator has just been replaced and no bleeding has yet been performed, DO NOT connect accumulator connectors and press the "Engine Start/Stop" button to the ignition ON position. (If the connectors are plugged in and the ignition is turned "ON", pressure will be built up in the accumulator.)
Press the "Engine Start/Stop" button to the ignition ON position, then start with "Section 2: Disable Electronic Controlled Brakes (ECB Invalid)".
This procedure releases pressure from the accumulator.
1. Connect a battery charger to maintain battery voltage.
2. Press the "Engine Start/Stop" button to the ignition ON position.
3. Using Techstream, navigate to the following menu:
ABS/VSC/TRAC
4. Select the "Utility" menu.
5. Select "ECB Utility".
6. Select "Zero Down" from the ECB Utility screen and press "Next".
7. Press "Next" to proceed.
8. Confirm the conditions listed on Techstream and press "Next".
9. Press "Next" to proceed.
10. Wait for the Zero Down process to finish and press "Next".
NOTE
The Zero Down process will take 20 seconds to complete.
The Low Pressure beeper will sound at the end of Zero Down to indicate the accumulator pressure is low. This is normal.
11. STOP DO NOT turn the ignition OFF and ON as instructed by Techstream. Just press "Next".
12. Once the "Zero Down" function is complete, press "Exit".
13. Navigate back to the ABS/VSC/TRAC utility menu, select "Data List", then "Accumulator Sensor", and check accumulator pressure. Pressure should be approximately 0.5 volts.
14. Press the "Engine Start/Stop" button to the ignition OFF position.
15. Disconnect both accumulator pump electrical connectors.
REPAIR PROCEDURE:
Section 2: Disable Electronic Controlled Brakes (ECB Invalid)
1. Press the "Engine Start/Stop" button to the ignition ON position.
2. Select "ECB Utility" from the Utility menu screen.
3. Select "ECB invalid" from the ECB Utility screen, and press "Next".
4. Press "Next" to proceed.
5. Confirm the conditions listed on Techstream and press "Next".
6. STOP - DO NOT turn the ignition OFF as instructed by Techstream. Press "Next" - DO NOT PRESS "Exit".
Section 3: Front Brake Bleed - Manual Process
NOTE
- Keep doors closed during bleeding.
- Ignition must be ON before starting this procedure.
1. Connect a clear vinyl tube to the FR (Front Right) bleeder screw.
2. Pump and hold pressure on the brake pedal while an assistant opens the bleeder screw.
NOTE
Make sure fluid level in reservoir does NOT fall below the low mark during this procedure.
3. When fluid/air bubbles stop coming out, tighten the bleeder screw and then release the brake pedal.
4. Repeat steps 2 and 3 until all air is removed from the FR line.
5. Connect a vinyl tube to the FL (Front Left) bleeder screw.
6. Repeat steps 2 and 3 until all air is removed from the FL line.
7. Press the "Engine Start/Stop" button to the ignition OFF position.
8. Connect the accumulator pump electrical connectors.
9. Press the "Engine Start/Stop" button to the ignition ON position.
IMPORTANT
- Accumulator pressure must be approximately 0.5 volts before starting the rear brake bleed procedure.
- You should NOT hear the accumulator pump motor run after the ignition is turned ON. If the accumulator pump runs after ignition is turned ON, return to "Section 1: Zero Down Accumulator Pressure".
10. Check and adjust the brake fluid level to MAX.
Section 4: Rear Brake Bleed
1. Select "Air Bleeding" from the Utility menu screen.
2. Press "Next" from the Air Bleeding Utility screen.
3. Confirm the conditions listed on Techstream and press "Next".
4. Select "Actuator has been removed" and press "Next".
5. STOP - DO NOT turn the ignition OFF as instructed by Techstream.
DO NOT unplug relays or disconnect accumulator connectors. Select "Next" - But DO NOT turn the ignition OFF.
6. Press "Next" through the Techstream screens concerning front brake bleed - front brakes have already been manually bled in section 3.
7. Press "Next" through the FR (Front Right) and FL (Front Left) brake bleed Techstream screens.
8. Press "Next" through the FL brake bleed Techstream screens.
9. Press "Next" at this screen since front brakes have already been manually bled.
10. Follow the instructions on Techstream and press "Next".
IMPORTANT
DO NOT press the brake pedal at this time.
A Attach the vinyl tube and bottle.
B Loosen the RR (Rear Right) bleeder screw.
NOTE
This step removes air from the RR (Rear Right) line and actuator.
11. DO NOT press the brake pedal.
During this step, Techstream opens the solenoid in the actuator for the RR line and then runs the accumulator pump.
NOTE
This step takes 30 seconds.
12. Tighten the bleeder screw and press "Next".
13. Adjust the brake fluid level to MAX before bleeding RL (Rear Left).
14. Follow instructions on Techstream for RL (Rear Left) brake, then press "Next".
NOTE
- Press and hold the brake pedal during RL (Rear Left) brake bleeding.
- The accumulator pump will run when the RL brake bleeder screw is opened.
15. Wait for completion of operations listed on Techstream, then press "Next".
16. Wait for completion of operations listed on Techstream, then press "Next".
NOTE
Lowering accumulator pressure takes 20 seconds.
17. Follow instructions on Techstream and press "Next".
NOTE
Techstream will instruct you to perform the accumulator Zero Down procedure 4 times.
18. Press "Next" to proceed.
19. Follow instructions on Techstream and press "Next".
20. Press "Next" after cycling the ignition switch OFF and then ON. Press "Next" AFTER the pump motor stops running.
21. Perform the "Zero Down" procedure 4 times, per Techstream. At the end of the 4 "Zero Down" procedures, the "Air bleeding is complete" message will be displayed. Press "Exit".
22.Check and adjust the brake fluid level to MAX.
Section 5: Reset Memory and Linear Valve Offset Calibration
1. Select "Reset Memory" from the Utility menu screen.
2. Confirm the conditions listed on Techstream and press "Next".
3. Press "Next" to proceed.
4. Press "Exit".
5. Select "ECB Utility" from the Utility menu screen.
6. Select "Linear Valve Offset" from the ECB Utility screen and press "Next".
7. Press "Next" to proceed.
8. Press "Next" to proceed.
9. Confirm the conditions listed on Techstream and press "Next".
10. Press "Next" to proceed.
11. Techstream is now performing Linear Valve Offset.
DO NOT depress the brake pedal at this time.
NOTE
This process takes 120 seconds.
12. Press "Exit".
13. Clear all stored DTCs.
14. Test drive vehicle to confirm NO warning lights illuminate and there are NO abnormal brake concerns.
15. Verify the squawk/bark noise has been eliminated.
NOTE:
Issue of this Technical Service Bulletin is to ensure that proper repair information is available. IT DOES NOT CONSTITUTE AN AUTHORIZATION FOR REPAIR. Normal provisions of the formal warranty policy, as applicable, will apply.