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Mitsubishi Pajero Pinin. Manual - part 250

ABS <4WD> –

On-vehicle Service

35B-23

Points In Waveform Measurement

Symptom

Probable causes

Remedy

Too small or zero waveform
amplitude

Faulty wheel speed sensor

Replace sensor

Waveform amplitude fluctuates
excessively (this is no problem if

Axle hub eccentric or with large runout

Replace hub

excessively (this is no roblem if
the minimum amplitude is 100 mV
or more)

Faulty ABS-ECU earth

Repair

Noisy or disturbed waveform

Open circuit in sensor

Replace sensor

Open circuit in harness

Correct harness

Incorrectly mounted wheel speed sensor

Mount correctly

ABS rotor with missing or damaged teeth

Replace ABS rotor

Caution
Because the wheel speed sensor cables move together with the front and rear suspension, they vibrate
greatly when driving over poor road surfaces. As a result, the sensor harnesses should also be shaken
when monitoring of output waveforms of the wheel speed sensors in order to simulate conditions such
as driving over poor road surfaces.

ABS WARNING LAMP RELAY CONTINUITY
CHECK

Battery voltage

Terminal No.

Power is not
supplied

Power is supplied

Hydraulic unit
and ABS-ECU

<L.H. drive vehicles>

<R.H. drive vehicles>

Hydraulic unit
and ABS-ECU

ABS <4WD> –

On-vehicle Service

35B-24

HYDRAULIC UNIT CHECK

Jack up the vehicle and support the vehicle with rigid racks placed at the specified jack-up points
or place the wheels which are checked on the rollers of the braking force tester.

Caution
(1) The roller of the braking force tester and the tyre should be dry during testing.
(2) When testing the front brakes, apply the parking brake, and when testing the rear brakes,

stop the front wheels by chocking them.

Turn the ignition key to the LOCK (OFF) position and set the MUT-

Caution
Turn the ignition key to the LOCK (OFF) position before connecting or disconnecting the MUT-

After checking that the shift lever <M/T> or the selector lever <A/T> is in neutral, start the engine.

Use the MUT-

to force-drive the actuator.

NOTE
(1) During the actuator test, the ABS warning lamp will illuminate and the anti-skid control will be

cancelled.

(2) When the ABS has been interrupted by the fail-safe function, the MUT-

actuator testing cannot

be used.

Turn the wheel by hand and check the change in braking force when the brake pedal is depressed.
When using the braking force tester, depress the brake pedal until the braking force is at the following
values, and check that the braking force decreases when the actuator is force-driven.

Front wheel

785 – 981 N

Rear wheel

588 – 784 N

The result should be as shown in the following diagram.

Pedal operation

Depressed

Released

Solenoid valve
position

Increase in pressure

Steady pressure

Reduction in pressure

Checking the
brake force

Lock

Drag force when the pedal is free

MUT-

actuator test

(Item No. 01, 02, 03, 04) start

2 seconds

Approx. 0.05 seconds

1 seconds

ABS <4WD> –

On-vehicle Service

35B-25

If the result of inspection is abnormal, correct according to the “Diagnosis Table”.

Diagnosis Table

No.

Operation

Judgement
– Normal

Judgement
– Abnormal

Probable cause

Remedy

(1) Depress brake pedal

to lock wheel.

(2) Using the MUT-

select the wheel to be

Brake force
released for 3
seconds after
locking

Wheel does not
lock when brake
pedal is de-
pressed

Clogged brake
line other than
hydraulic unit

Check and clean
brake line

select the wheel to be
checked and force the
actuator to operate.

(3) Turn the selected

wheel

manually

locking.

pressed.

Clogged hydrau-
lic circuit in
hydraulic unit

Replace hydrau-
lic unit assembly

wheel manually to
check the change of
brake force.

Brake force is
not released

Incorrect hydrau-
lic unit brake
tube connection

Connect correct-
ly

Hydraulic unit
solenoid valve
not functioning
correctly

Replace hydrau-
lic unit assembly

After inspection, disconnect the MUT-

immediately after turning the ignition switch to OFF.

REMEDY FOR A FLAT BATTERY

When booster cables are used to start the engine when the
battery is completely flat and then the vehicle is immediately
driven without waiting for the battery to recharge itself to some
extent, the engine may misfire, and driving might not be
possible.
This happens because ABS consumes a great amount of
current for its self-check function; the remedy is to either allow
the battery to recharge sufficiently, or to disconnect the
ABS-ECU connector, thus disabling the anti-skid brake system.
The ABS warning lamp will illuminate when the ABS-ECU
connector is disconnected.
After the battery has sufficiently recharged, connect the
ABS-ECU connector and restart the engine; then check to
be sure the ABS warning lamp is not illuminated.

DISCONNECTING ABS-ECU CONNECTOR

Move the lock lever of the ABS-ECU connector as shown
in the illustration, and then disconnect the ABS-ECU connector.

Lock lever

Hydraulic unit and
ABS-ECU

ABS <4WD> –

Hydraulic Unit and ABS-ECU

35B-26

HYDRAULIC UNIT AND ABS-ECU

REMOVAL AND INSTALLATION

Pre-removal Operation

Brake Fluid Draining

Air Cleaner Removal (Refer to GROUP 15.)

Post-installation Operation

Brake Fluid Supplying and Brake Line Bleeding
(Refer to GROUP 35A – On-vehicle Service.)

Hydraulic Unit Inspection (Refer to P.35B-24.)

Air Cleaner Installation (Refer to GROUP 15.)

<L.H. drive vehicles>

15 Nm

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