Montero V6-3.8L SOHC (2005)
Hydraulic Brake Booster: Component Tests and General Diagnostics
HBB Operating Check
HBB OPERATING CHECK
CAUTION: If the diagnostic trouble code is stored in the M-ASTC-ECU memory, erase it after diagnosis is completed.
Function and Operation Check of Power Supply System
1. Depress the brake pedal repeatedly more than 40 times until the pedal depressing force feels heavy with the ignition switch at the "LOCK" (OFF)
position to release the pressure of HBB power supply system.
2. Check that the fluid level in the reservoir is at the "MAX" line.
3. Chock the wheels and release the parking brake.
4. Turn the ignition switch to the "ON" position and measure how long it takes for the pump motor to start, then stop.
Standard value: 20 - 80 seconds
5. After the pump motor stops, start the engine to confirm that the brake warning light does not come on.
6. Stop the engine and turn the ignition switch to the "ON" position again.
7. Confirm that the pump motor operates, then stops when the brake pedal is depressed repeatedly 4 to 5 times.
8. Depress the brake pedal repeatedly 4 to 5 times again to measure how long it takes for the pump motor to start, then stop.
Standard value: 2 - 11 seconds
9. Check and confirm the following items 120 seconds or more after turning ON the ignition switch.
CAUTION: Check and confirm the following items 120 seconds or more after turning the ignition switch to the "ON" position.
10. Confirm that the buzzer sounds and the brake warning light illuminates when the brake pedal is fully depressed 15 to 20 times within 10 seconds.
HBB Simple Check
1. Depress the brake pedal repeatedly for more than 40 times until the pedal depressing force feels heavy with the ignition switch at the "LOCK"
(OFF) position to release the pressure of HBB power supply system.
2. Check the change of pedal height by turning the ignition switch to the "ON" position while depressing the brake pedal. It is normal if the pedal is
lowered at this time. If it is not lowered, the system is defective.
Check Using Simple Tester
1. Depress the brake pedal repeatedly more than 40 times until the pedal depressing force feels heavy with the ignition switch at the "LOCK" (OFF)
position to release the pressure of HBB power supply system.
2. Connect a pressure gauge and a pedal depression gauge as shown in the illustration and bleed air from the pressure gauge.
3. Perform the operation test without booster according to the following method. Depress the brake pedal repeatedly more than 40 times with the
ignition switch at"LOCK" (OFF) position to bleed pressure from the HBB power supply system. Measure the relation between the brake pedal
depressing force and the hydraulic pressure.
