ABS <4WD> -
On-vehicle Service
35B-29
HYDRAULIC BRAKE BOOSTER (HBB) - HYDRAULIC UNIT CHECK
Caution
Turn the ignition switch to the LOCK (OFF) position when connecting and disconnecting the MUT-
II
.
(1) Jack up the vehicle, and support it in th e specified location using a rigid rack, or place the vehicle
on the rollers of a brake force tester.
Caution
1. The rollers of the brake force tester and the vehicle tyres should be dry during checking.
2. If using a brake force tester, apply the parking brake when testing the front brakes, and
use a wheel lock to lock the front wheels when testing the rear brakes.
(2) Turn the ignition switch to the LOCK (OFF) position, and connect the MUT-
II
to the diagnosis connector.
(3) After checking that the selector lever is in the N position, start the vehicle’s engine.
(4) Operate the MUT-
II
to carry out the actuator tests.
NOTE
1) When actuator tests are being carried out, the ABS warning lamp will illuminate and ABS control
will be stopped.
2) MUT-
II
actuator tests cannot be carried out when the operation of the ABS-ECU has been stopped
by the fail-safe function.
(5) Rotate the wheel by hand and check that the brake force changes when the brake pedal is depressed.
If using a brake force tester, depress the brake pedal until the brake force reaches the following value,
and then cheek that the brake force changes when the actuator test is carried out.
Front wheels 785 - 981 N
Rear wheels 785 - 981 N
Caution
The solenoid valves should be driven one wheel at a time, and the brake pedal should be
released each time a wheel is checked.
The following illustration shows this in graphical form.
Pedal operation
Depress
Release
Solenoid valve position
Increase
Hold
Decrease
Brake force
check
Locked
Drag force when
pedal is released
2s
1s
MUT-
II
actuator test (Item No. 01, 02, 03, 04) start
www.WorkshopManuals.co.uk
Purchased from www.WorkshopManuals.co.uk
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