Mitsubishi Lancer Evolution VI. Manual — part 71
ABS –
Troubleshooting
35B-34
Terminal No.
Normally
Signal name
38 – body ground
Solenoid valve IN (FR)
8.04 – 9.04
Ω
39 – body ground
ECU ground
Conducting
45 – body ground
Solenoid valve IN (RL)
8.04 – 9.04
Ω
46 – body ground
Solenoid valve OUT (FR)
4.04 – 4.54
Ω
<EVOLUTION-V, VI>
Terminal No.
Signal name
Normally
1 – body ground
Solenoid valve OUT (FL) output
4.04 – 4.54
Ω
2 – body ground
Solenoid valve OUT (RR) output
4.04 – 4.54
Ω
3 – body ground
Solenoid valve IN (RR) output
8.04 – 9.04
Ω
7 – 20
Wheel speed sensor (FL) input
1.4 – 1.8 k
Ω
8 – 21
Wheel speed sensor (RR) input
1.4 – 1.8 k
Ω
9 – 22
Wheel speed sensor (RL) input
1.4 – 1.8 k
Ω
10 – 23
Wheel speed sensor (FR) input
1.4 – 1.8 k
Ω
14 – body ground
Solenoid valve IN (FL) output
8.04 – 9.04
Ω
15 – body ground
Ground
Conducting
25 – body ground
Ground
Conducting
40 – body ground
Solenoid valve OUT (RL) output
4.04 – 4.54
Ω
41 – body ground
Solenoid valve OUT (FR) output
4.04 – 4.54
Ω
42 – body ground
Ground
Conducting
48 – body ground
Valve relay monitor input
Conducting
49 – body ground
Motor relay monitor input
Conducting
51 – body ground
Solenoid valve IN (RL) output
8.04 – 9.04
Ω
52 – body ground
Solenoid valve IN (FR) output
8.04 – 9.04
Ω
ABS –
On-vehicle Service
35B-35
ON-VEHICLE SERVICE
WHEEL SPEED SENSOR OUTPUT VOLTAGE
CHECK
1.
Lift up the vehicle and release the parking brake.
2.
Disconnect the ABS-ECU connector, and then measure
the output voltage at the harness-side connector.
Caution
Insert the probe in the connector from the harness
side after releasing the double lock. Inserting it from
the terminal side could cause poor contacts.
3.
Rotate the wheel to be measured at approximately 1/2– 1
rotation per second, and check the output voltage using
a circuit tester (ACmV range) or an oscilloscope.
Terminal numbers
<EVOLUTION-IV>
Front left
Front right
Rear left
Rear right
6
8
9
7
19
21
22
20
<EVOLUTION-V, VI>
Front left
Front right
Rear left
Rear right
7
10
9
8
20
23
22
21
Output voltage
When measuring with a circuit tester:
70 mV or more
When measuring with an oscilloscope:
200 mV p-p or more
4.
If the output voltage is lower than the above values, the
following causes are suspected. Check the wheel speed
sensors and replace if necessary.
D
Too large gap between wheel speed sensor pole piece
and ABS rotor
D
Faulty wheel speed sensor
ABS-ECU connector (harness side)
<EVOLUTION-IV>
ABS-ECU connector (harness side)
<EVOLUTION-V, VI>
ABS –
On-vehicle Service
35B-36
Inspecting Waveforms with an Oscilloscope
Use the following method to observe the output voltage
waveform from each wheel sensor with an oscilloscope.
Check the connection of the sensor harness and connector
before using the oscilloscope.
Start the engine, and rotate the wheels by engaging 1st gear.
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
c
y (t
p
the minimum amplitude is 100 mV
or more)
Faulty ABS-ECU ground
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 rotor
Caution
The wheel speed sensor cable moves following motion of the front or rear suspension. Therefore,
it is likely that it has an open circuit only when driving on rough roads and it functions normally
on ordinary roads. It is, therefore, recommended to observe sensor output voltage waveform also
under special conditions, such as rough road driving.
When turning by hand
When idling (5 – 6 km/h),
1st gear
10.0 ms/DIV 1 V/DIV
ABS –
On-vehicle Service
35B-37
HYDRAULIC UNIT CHECK
Caution
Turn the ignition switch off before connecting or disconnecting the MUT-
II
.
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 OFF position and set the MUT-
II
.
3.
After checking that the shift lever is in neutral, start the engine.
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 used.
4.
Use the MUT-
II
to force-drive the actuator.
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
294 – 490 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-
II
actuator test
(Item No. 01, 02, 03, 04) start
1 seconds
2 seconds
about 0.05 seconds
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