wheel MITSUBISHI 3000GT 1991 Service Manual

35-30SERVICE BRAKES -Anti-lock Braking System Troubleshooting
METHOD OF CLEARING DIAGNOSIS
ACTUATOR TEST FUNCTION
CODE MEMORYCautionThe actuator can be forcibly driven in the following
way by using the MUT.
lWhen servicing is finished, clear the diagno-
sis code memoryNOTElThe actuator test cannot be carried out when the
Trouble codes cannot be cleared from memoryABS ECU system is in fail safe mode.
when the ABS-ECU system is in fail safe mode.
Proceed to diagnosis and repair.l When using forced drive using the MUT, the
vehicle must be stopped.
(1) Clear memory using MUT.
lDuring forced drive using the MUT, forced drive
(No. 7
“DIAG. ERASE” in the actuator test isoperation is stopped, when any wheel speed
selected to erase the diagnosis code.)reaches 10 km/h (6 mph).
(2) After clearing, recheck the diagnosis codes, and
check that memory is .cleared.
Actuator test specifications
Not usedStart of forced drive
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[Explanation][Hint]
The ABS ECU detects breaks in the wheel speedIn addition to a broken wire/short circuit in the wheel
sensor wire. This trouble code is output if the wheelspeed sensor, also check whether the sensor gap is
speed sensor signal is not input (or short circuited)too large, sensor harness wire is broken, or sensor
or if its output is low when starting to drive or whileharness and body connector are not properly con-
driving.
netted.E-2 When diagnosis code“15 VEH. SPD. SNSR.” is displayed
[Explanation]l Broken sensor harness
This trouble code is output when there is anl Poor connection of connector
abnormality (other than broken wire or short circuit)
NOTEin any of the wheel speed sensor output signals
(1) If contact is poor, check the sensor cable by
while driving.bending and lightly stretching it.
[Hint](2) Except for the case where a fault condition
The following can be considered as the cause of theexists in the system, but the inspection results
wheel speed sensor output abnormality.are normal; if an abnormality cannot be found in
l Distortion of rotor, teeth missingthe sensor. circuit displayed as abnormal, erase
lLow frequency noise interference when sensorthe diagnosis code and turn the ignition switch
harness wire is brokento OFF once, and then test-drive again.
l Noise interference in sensor signalIf the same trouble code is output, replace the
lSensor output signal is below the standard valueABS ECU. If the trouble does not occur any-or amplitude modulation is over the standardmore, the problem is likely to be with the ABS
ECIJ.\value. Using an oscilloscope to measure the
wave shape of the wheel speed sensor output
signal is very effective.
I\-- -.(If the trouble is in the speed sensor circuit, butdis difficult to recreate, it will recur even after the
ABS ECU has been replaced.)35-38
SERVICE BRAKES -Anti-lock Braking System Troubleshooting
E-lWhen the following diagnosis codes are displayed “11 FR SNSR. OPEN”
“12 FL SNSR. OPEN” “13 RR SNSR. OPEN” “14
RL SNSR. OPEN”
d
SPEED SENSOR
FRONTCLH) FRONTGWR!%R(LH) REARmi
m I@m @
If?All110130125ASS-ECI.+tB5
8
8I
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SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-39
Check flow connected with wheel
speed sensorNOTECheck speed sensor harness and connector connection
and then observe with oscilloscope. (Refer to
P.35-57.)No ,
Is the resistance value of the wheel
speed sensor part normal?
Standard value: 0.8 - 1.2 kR
z Malfunction of wheel speed
sensor
Yes
,I”
/
LY14N0127
L14N0181
1Yes
-NoCheck the output of each
wheel speed sensor with an
oscilloscope, including the
waveform. (Refer to
P.35-57.)Is the output voltage for each
wheel speed sensor over
the standard value and is
the waveform normal?
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SERVICE BRAKES - Service Adiustment Procedures
i14LO29C
1Al 0781
14LO291141029
1. Visually check the brake pad thickness through the inspec-
tion hole in the caliper body.
Standard value: IO.0 mm
(.39 in.)
Limit: 2.0 mm (.08 in.)
Caution
Replace the pad if worn beyond the limit. At this time,
replace the pads on right and left wheels as a set.
2. Remove the guide pin, raise the caliper assembly, and
support it with a wire, etc.
Caution
The guide pin has been coated with special
Igrease. Do
not wipe off the special grease on the lock pin, and do
not contaminate the lock pin.
3. Remove the following parts from the caliper support.@ Pad and wear indicator assembly
8 F$$ assembly
3 I@ Outer shim
4. Measure the rotating torque of the hub with the pads
removed to determine brake drag torque after pads are
installed.
5. Install the pad clips to the caliper support in position.
\14AO400
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35-50SERVICE BRAKES - Service Adjustment Procedures
Pad pin
1 AFnn97
6.Clean the piston and, using the special tool, push the piston
into the cylinder.
7.With care not to allow the piston boot to be wedged, lower
the caliper assembly and fit the lock pin.
8. Using the following procedure, check the brake drag
‘d ,
torque.@ Start the engine and depress and hold the brake pedal
for five seconds.@ Stop the engine. (Approx. 200 N
[44 Ibs.])@ Rotate the brake disc ten turns in the forward direction.@ Using a spring balance, check the brake drag force.
9. If the difference between the brake drag force and hub
rotating force exceeds the standard value, disassemble the
piston and check the piston sliding surfaces for dirt and
rust, piston seal for deterioration, and lock pin and guide pin
for sliding motion.
Standard value: 70 N (15.4 Ibs.)
[4 Nm (3 ftlbs.)] or less
1. Visually check the brake pad’ thickness. Through the
opening in the caliper body.
Standard value: 10.0 mm
(-39 in.)
Limit: 2.0 mm
(.08 in.)
Caution
‘L&iReplace the pad if worn beyond the limit. At this time,
replace the pads on right and left wheels as a set.
I2. Remove the clip and, holding the cross spring with hand,
remove the pad pins.
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35-52SERVICE BRAKES - Service Adjustment Procedures
14FOO94
k.!! I14FOO427. Using the following procedure, check the brake drag
torque.@ Start the engine and depress and hold the brake pedal
’for five seconds. [Approx. 200 N (44
Ibs.)]@ Stop the engine.@ Rotate the brake disc ten turns in the forward direction.@ Using a spring balance, check the brake drag force.
8. If the difference between the brake drag force and hub
rotating force exceeds the standard value, disassemble the
piston and check the piston sliding surfaces for dirt and
rust, piston seal for deterioration, and lock pin and guide pin
for sliding motion.
Standard value: 70 N (15.4
Ibs.) [4 Nm (3 ft.lbs.)] or less
INSPECTION OF FRONT BRAKE DISC THICKNESS1. Remove dirt and rust off the surface of the brake disc.
2.Measure the thickness of disc at four or more places of the
pad contacting surface.
Standard value:
24.0 mm (.94 in.)
30.0 mm (1.18 in.)
,Limit:
22.4 mm (.88 in.)
28.4 mm (1.12 in.)
3.If the wear exceeds the limit even at one place, replace the
right and left discs and brake pads as a set.
FRONT BRAKE DISC RUN-OUT CHECKM35FSAF
1. Remove the front brake assembly; and support it with a
wire, etc.
TSB Revision2. Place a dial gauge approximately 5 mm
(.2 in.) from the
outer circumference of the brake disc, and measure the
run-out of the disc.
Limit: 0.10 mm (.004 in.) or less
NOTESecure the disc to the hub with wheel nuts.

L.
SERVICE BRAKES -Service Adjustment Procedures35-53
I14A0398
14F003r
i14A04014NOO27
7
FRONT BRAKE DISC RUN-OUT CORRECTION
M35FFAC
1.If the run-out of the brake’disc is equivalent to or exceeds
the limit specification, change the phase of the disc and
hub, and then measure the run-out again.
(1) Before removing the brake disc, chalk both sides of the
wheel stud on the side at which run-out is greatest.
(2) Remove the brake disc, and then place a dial gauge as
shown in the illustration; then move the hub in the axial
direction and measure the play.
Limit: 0.05 mm (.002 in.)
If the play is equivalent to or exceeds the limit, replace
the front hub unit bearing.
(3) If the play does not exceed the limit specification, and
then check the run-out of the brake disc once again.
Mount the brake disc on the position dislocated from
the chalk mark.
2.If the run-out cannot be corrected by changing the phase of
the brake disc, replace the disc.
REAR DISC BRAKE PAD CHECK AND REPLACE-
MENTM35FUAE
1.Check brake pad thickness through caliper body check port.
Standard value: 10.0 mm
(39 in.)
Limit: 2.0 mm
(08 in.)
Caution
1.When the limit is exceeded, replace the pads at both
sides, and also the brake pads for the wheels on the
opposite side at the same time.
2.If there is a significant difference in the thicknesses
of the pads on the left and right sides, check the
sliding condition of the piston, lock pin sleeve and
guide pin sleeve.
2. Loosen the parking brake cable (from the vehicle interior),
and disconnect the parking brake end installed on the rear
brake assembly.
3. Remove lock pin. Lift caliper assembly and retain with
wires.
Caution
Do not smear special grease on lock pin or make it
dirty.
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SERVICE BRAKES - Service Adjustment Procedures
4. Remove the following parts from caliper support.@ Outer shim@ Pad assembly@ Pad & wear indicator assembly@ Clip@ Inner shim A@ Inner shim B
d
14N0031
f\
/0014N013714A040;14N003:
14AO401
l%FLision
14N01365. Measure hub torque with pad removed to measure brake
drag torque after pad installation.
On vehicles with VCU-equipped LSD, disengage the drive
shaft and companion flange.
NOTESecure the disc to the hub with wheel nuts.
6. Securely attach the pad clip to the caliper support.
Caution
Do not deposit
&ease or other dirt on pad or brake disc
friction surfaces.
7.Clean the piston and then push the piston into the cylinder.
8.With care not to allow the piston boot to be wedged, lower
the caliper assembly and fit the lock pin.
9. Check brake drag torque as follows.
(I) Start engine and hold brake pedal down for 5 seconds.
[Approx. 200 N (44
Ibs.)](2) Stop engine.
(3) Turn brake disc forward
10 times.
(4) Check brake drag torque with spring scale.
If the difference between brake drag torque and hub torque
exceeds the standard value, disassemble piston and clean
piston. Check for corrosion or worn piston seal, andcheck
the sliding condition of the lock pin sleeve and guide
pinl/jsleeve.
Standard value: 70 N (15.4
Ibs,,) [4 Nm (3 ft.lbs.)] or less

SERVICE BRAKES - Service Adjustment Procedures35-57
i
~18~17~16~15~14~13~12~11~10~ 9 18 I 7 16 I 5 14 13 12 1 1 1[35~34~33~32~31~30~29~28~27~26~25~24~23~22~21~20~19~Check connector
ECU
/m/Body harness
MB991 35614N018(
I I I 2When turned manually
~---~---~-.-~---[--.I 1MEASUREMENT OF
WHEEL SPEED SENSOR
OUTPUT VOLTAGEM35FOAO
1. Lift up the vehicle and release the parking brake.
2.Disconnect the ECU harness connector and measure with
the adapter harness (MB991 356) connected to the harness
side connector.
Caution
1. Never insert a probe, etc. into the connector as it
may result in poor contact later.
2.Do not connect the connector (Special Tool) markedwith “r+”except when recording the waveform on a
driving test. In such a case, connect the connector
to the ECU.
Terminal No. (same for AWD and FWD)
FL
RRFRRL
4
24218
52623393. Manually turning the wheel to be measured by
112 to 1
turn/second, measure the output voltage with a circuit
tester or oscilloscope.
Output voltage:
When measured with circuit tester: 70
mV or more
When measured with oscilloscope (max. voltage): 100
mV or more
Probable causes of low output voltage
l Speed sensor pole piece-to-rotor clearance too large
l Faulty speed sensor
4. Then, in order to observe the output state of the wheel
speed sensors, shift into low gear
(AWD vehicle) and drive
the wheels, observe the output voltage waveform of each
wheel speed sensor with an oscilloscope.
In the case of the FWD vehicle, observe the waveform with
an oscilloscope; for the front wheels, shift into low gear and
drive the wheels; for the rear wheels, turn the wheels
manually at a constant speed.
NOTE
1.Waveform may also be observed by actually driving the
vehicle.
2.The output voltage is low when the wheel speed is low
and increases as the wheel speed increases.
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35-58SERVICE BRAKES - Service Adjustment Procedures
POINTS IN WAVEFORM MEASUREMENT
Symptom
Too small or zero waveform
amplitudeProbable causes
Faulty wheel speed sensorRemedy
Replace sensor
Incorrect pole piece-to-rotor clearance
Adjust clearance
Waveform amplitude fluctuates
excessively (this is no problem ifAxle hub eccentric or with large runout
Replace hub
the minimum amplitude is
100 mV
or more)
Noisy or disturbed waveformOpen circuit in sensor
Open circuit in harness
Incorrectly mounted wheel speed sensor
Rotor with missing or damaged teethReplace sensor
Correct harness
Mount correctly
Replace rotor
NOTEThe 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,
(ME!991 377)12FOO5i
INSPECTION OF HYDRAULIC UNITINSPECTION BY FEEL
(I) Jack up the vehicle and support the vehicle with rigid racks
placed at the specified jack-up points.
(2) Release the parking brake and determine the drag force
(drag torque) of each wheel by feel.
LJ(3) Set the MUT through the adapter harness (MB991377) as
illustrated.
(4) After confirming that the shift lever or selector lever is in
the neutral position, start the engine.
The ABS warning light lights up, it goes into the MUT mode.
In the MUT mode, ABS does not function.
(5) Operate the MUT to force the actuator to operate (item No.
04, 05, 06).
(6) Turning the wheel manually, check the change of the
braking force when the brake pedal is depressed.
The change should be as shown in the following illustration.
NOTEWhile the ABS is in the fail safe mode, the MUT actuator
test cannot be made.
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