Mitsubishi Lancer Evolution IX. Manual — part 527

ON-VEHICLE SERVICE

ANTI-SKID BRAKING SYSTEM (ABS)

35B-139

3. Manually turn the wheel to be measured 1/2 to 1

turn/second. Measure the output voltage with a
voltmeter or oscilloscope.
NOTE: The output waveform is low when the
wheel speed is low. Similarly, it will be higher as
the wheel speed increases. Waveform may also
be observed by driving the vehicle.

Output voltage:

• Minimal voltmeter reading: 42 mV

• Maximum voltmeter reading: 300 mV

• Minimal oscilloscope reading: 120 mV

• Maximum oscilloscope reading: 600 mV

Probable causes of low output voltage

• Wheel speed sensor pole piece-to-wheel speed

rotor clearance too large

• Faulty wheel speed sensor

NOTE: Check the connection of the wheel speed
sensor harness and connector before using the
oscilloscope.

4. To observe the waveform with an oscilloscope:

• Front Wheels: Shift into low gear and drive the

wheels.

• Rear Wheels: Turn the wheels manually at a con-

stant speed.

POINTS IN WAVEFORM MEASUREMENT

NOTE: The wheel speed sensor cable moves in relation to motion of the front or rear suspension. Therefore,
it is likely that it has an open circuit only when driving on rough roads but it functions normally when driving on
smooth roads. It is recommended to observe sensor output voltage waveform also under special conditions,
such as driving on a rough road.

Terminal No.
Front left

Front right

Rear left

Rear right

22

29

6

8

31

30

7

9

AC211695AB

AC000949 AF

When turned by hand

When idling (5 − 6 km/h), with 1st gear

[10.0 ms/DIV IV/DIV]

Symptom

Probable causes

Remedy

Too small or zero waveform
amplitude

Faulty wheel speed sensor or
excessive gap between it and the
wheel speed rotor

Replace wheel speed sensor

Waveform amplitude fluctuates
excessively (This is no problem if
the minimum amplitude is 100 mV
or more)

Axle hub eccentric or with large
runout

Replace hub assembly

Faulty ABS-ECU earth

Repair harness wires

Noisy or disturbed waveform

Open circuit in wheel speed sensor Replace wheel speed sensor
Open circuit in harness

Repair harness wire

Incorrectly mounted wheel speed
sensor

Mount wheel speed sensor
correctly

Wheel speed rotor with missing or
damaged teeth

Replace wheel speed rotor

ON-VEHICLE SERVICE

ANTI-SKID BRAKING SYSTEM (ABS)

35B-140

HYDRAULIC UNIT CHECK

M1352001700642

CAUTION

• The roller of the braking force tester and the

tyre should be dry during testing.

• When testing the front brakes, apply the park-

ing brake. When testing the rear brakes, stop
the front wheels with chocks.

1. Jack up the vehicle. Then support the vehicle with

rigid racks at the specified jack-up points or place
the front or rear wheels on the rollers of the
braking force tester.

2. Release the parking brake, and feel the drag force

(drag torque) on each road wheel. When using
the braking force tester, take a reading of the
brake drag force.

3. Turn the ignition switch to the "LOCK" (OFF)

position.

CAUTION

To prevent damage to the M.U.T.-II/III, always turn
the ignition switch to the "LOOK" (OFF) position
before connecting or disconnecting the
M.U.T.-II/III.

4. Connect the M.U.T.-II/III as shown in the

illustration.

5. After checking that the shift lever is in neutral,

start the engine.

6. Use the M.U.T.-II/III to force-drive the actuator.

For the M.U.T.-II/III, follow the steps below.
(1) Select "Interactive Diagnosis" from the start-up

screen.

(2) Select "System select."
(3) Choose "ABS" from the "CHASSIS" tab.
(4) Select "Actuator Test" from "ABS" screen

AC207179AB

M.U.T.-II

16-PIN

<Using the M.U.T.-II>

AC210056

AC

MB991911

16-PIN

MB991827

MB991824

<Using the M.U.T.-III>

ON-VEHICLE SERVICE

ANTI-SKID BRAKING SYSTEM (ABS)

35B-141

(5) Choose an appropriate item for hydraulic unit

check.

NOTE: The ABS system will switch to the
M.U.T.-II/III mode and the ABS warning lamp
will illuminate.

NOTE: When the ABS has been interrupted by
the fail-safe function, the M.U.T.-II/III actuator
testing cannot be used.

7. 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
changes to the reading taken in step 2. The result
should be as shown in the diagram above.

AC000954AH

M.U.T.-II/III actuator test
(Item No.01, 02, 03, 04) start

1 seconds

2 seconds

3 seconds

Depressed

Released

Increase in pressure

Reduction in pressure

Steady pressure

Lock

Drag force when the
pedal is free

Pedal
operation

Solenoid
valve
position

Checking
the brake
force

Approx. 0.05 second

Front wheel

785

− 981 N

Rear wheel

588

− 784 N

ON-VEHICLE SERVICE

ANTI-SKID BRAKING SYSTEM (ABS)

35B-142

8. If the result of inspection is abnormal, repair

according to the Diagnosis Table below.

9. After inspection, disconnect the M.U.T.-II/III

immediately after turning the ignition switch to the
"LOCK" (OFF) position.

IN THE EVENT OF A DISCHARGED
BATTERY

M1352003500600

WARNING

If the ABS is not operating, the vehicle pos-
ture will be unstable during braking, Do not
drive the vehicle with the ABS-ECU connec-
tor disconnected or with the ABS not operat-
ing for any other reason.

If the engine is started using a booster cable when
the battery is completely flat, and the vehicle is then
driven without waiting for the battery to be recharged,
the engine may misfire and it may not be possible to
drive the vehicle. This is because the ABS consumes
a large amount of current when carrying out its initial
checks. If this happens, recharge the battery fully.

Diagnosis Table

M.U.T.-II/III Display Operation

Inspection result

Judgment Probable cause

Remedy

01 FR VALVE
02 FL VALVE
03 RR VALVE
04 RL VALVE

• Depress brake pedal

to lock wheel.

• Using the M.U.T.-II/III,

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

• Turn the selected

wheel manually to
check the change of
brake force.

Brake force is
released for
three seconds
after wheels
have been
locked.

Normal −

−

Wheel does not
lock when brake
pedal is
depressed.

Abnorm
al

Clogged brake
line other than
hydraulic unit

Check and clean
brake line

Clogged
hydraulic circuit
in hydraulic unit

Replace
hydraulic unit
assembly

Brake force is
not released

Incorrect
hydraulic unit
brake tube
connection

Connect correctly

Hydraulic unit
solenoid valve
not functioning
correctly

Replace
hydraulic unit
assembly