Mitsubishi Lancer Evolution 7. Manual — part 322
ABS <4WD> -
On-vehicle Service
35B-27
4. Rotate the wheel to be measured at approximately 1/2 - 1
rotation per second, and check the output voltage using a
circuit tester or an oscilloscope.
Wheel speed
sensor
Front
left
Front
right
Rear
left
Rear
right
Terminal No.
22
29
6
8
31
30
7
9
Output voltage
When measuring with a circuit tester:
42 mV or more
When measuring with an oscilloscope:
120 mV p-p or more
5. The followings are suspected if the output voltage is lower
than the value described above. Check the wheel speed
sensor, and replace if necessary.
D
Too large clearance between the pole piece of the
wheel speed sensor and ABS rotor
D
Faulty wheel speed sensor
Inspecting Waveforms With An Oscilloscope
Use the following method to observe the output voltage
waveform from each wheel speed sensor with an oscilloscope.
D
Start the engine, and rotate the front wheels by engaging
1st gear. Turn the rear wheels manually so that they
rotate at a constant speed.
NOTE
1. The waveform measurements can also be taken while
the vehicle is actually moving.
2. The output voltage will be small when the wheel speed
is low, and similarly it will be large when the wheel speed
is high.
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 problem if
the minimum amplitude is 100 mV
or more)
Faulty ABS-ECU earth
Repair
When turning by hand
When idling (5 - 6 km/h), 1st gear
10.0 ms/DIV 1 V/DIV
ABS <4WD> -
On-vehicle Service
35B-28
Symptom
Remedy
Probable causes
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.
HYDRAULIC UNIT CHECK
1. 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.
2. Turn the ignition key to the “LOCK” (OFF) position and set the MUT-II.
Caution
Turn the ignition key to the “LOCK” (OFF) position before connecting or disconnecting the
MUT-II.
3. After checking that the shift lever is in neutral, start the engine.
4. Use the MUT-II 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-II actuator testing cannot
be carried out.
5. 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
ABS <4WD> -
On-vehicle Service
35B-29
The result should be as shown in the following diagram.
Approx. 0.05 seconds
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-II actuator test
(Item No. 01, 02, 03, 04) start
2 seconds
1 seconds
6. If the result of inspection is abnormal, correct according to the following “Diagnosis Table.”
Diagnosis Table
No.
MUT-II
display
Operation
Judgement
Probable
cause
Remedy
display
Normal
Abnormal
cause
01
FR VALVE
(1) Depress the brake
pedal to lock wheel.
(2) Using
the
MUT-II,
select the wheel to be
checked and force the
Brake force
released for 3
seconds after
locking.
Wheel does
not lock when
brake pedal
is depressed.
Clogged
brake line
other than
hydraulic unit
Check and
clean brake
line.
02
FL VALVE
checked and force the
actuator to operate.
(3) Check the brake force
for the selected wheel
using a brake force
t t
b
t ti
th
Clogged
hydraulic
circuit in
hydraulic unit
Replace
hydraulic unit
assembly.
03
RR VALVE
g
tester or by rotating the
wheel by hand.
Brake force is
not released.
Incorrect
hydraulic unit
brake tube
connection
Connect
correctly.
04
RL VALVE
Hydraulic unit
solenoid
valve not
functioning
correctly
Replace
hydraulic unit
assembly.
7. After checking, turn the ignition switch to the “LOCK” (OFF) position and then disconnect the MUT-II.
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. If this happens,
recharge the battery fully.
Caution
The vehicle posture will be unstable during braking, so
do not drive the vehicle with the ABS-ECU connector
disconnected or with the ABS not operating for any other
reason.
ABS <4WD> -
Hydraulic Unit and ABS-ECU
35B-30
HYDRAULIC UNIT AND ABS-ECU
REMOVAL AND INSTALLATION
<L.H. drive vehicles>
Pre-removal Operation
D
Strut Tower Bar Removal (Refer to GROUP 42.)
D
Brake Fluid Draining
Post-installation Operation
D
Brake Fluid Supplying and Brake Line Bleeding
(Refer to GROUP 35A - On-vehicle Service.)
D
Hydraulic Unit Check (Refer to P.35B-28.)
D
Strut Tower Bar Installation (Refer to GROUP 42.)
2
3
4
2
2
2
15 ± 2 N·m
25 ± 6 N·m
1
25 ± 6 N·m
Removal steps
A
A"
1. Harness connector
"
AA 2. Brake pipe connection
A
B"
3. Hydraulic unit and ABS-ECU
4. Hydraulic unit bracket assembly
Нет комментариевНе стесняйтесь поделиться с нами вашим ценным мнением.
Текст