1991 MITSUBISHI 3000GT wheel

35-12SERVICE BRAKES -Anti-lock Braking System Troubleshooting
METHOD OF CLEARING DIAGNOSIS
ACTUATOR TEST FUNCTION
CODE MEMORYThe actuator can be forcibly driven in the following
Cautionway by using the MUT.
lWhen servicing is finished, clear the diagno-
sis code memory.NOTEd
lThe actuator test cannot be carried out when the
Trouble codes cannot be cleared from memoryABS ECU system is in fail safe.
when the ABS ECU system is in fail safe. Proceed tol When using forced drive using the MUT, the
diagnosis and repair.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 diaanosis code.)reaches 10 km/h (6 mph).
(2) After clearing, recheck the diagnosis codes, and
check that memory is cleared.
Actuator test specifications
No.MUT display
01FR VALVE A
02
FL VALVE A03
REAR VALVE A04
FR VALVE M
05
FL VALVE M06
REAR VALVE MDrive solenoid
valve and motorDrive pattern
Not used
Solenoid valve and
pump motor for
each HU corres-
ponding channel.

Start of forced drive
End of forced drive
1440588
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35-20SERVICE BRAKES -Anti-lock Braking System Troubleshooting
the following diagnosis codes are displayed “11 FR SNSR. OPEN”
“12 FL SNSR. OPEN” “13 RR SNSR. OPEN” “14 RL SNSR. OPEN”
[Explanation]
The ABS ECU detects breaks in the wheel speed
sensor wire. This trouble code is output if the wheel
speed sensor signal is not input (or short circuited)
or if its output is low when starting to drive or while
driving.[Hint]
In addition to a broken wire/short circuit in the wheel
speed sensor, also check whether the sensor gap is
too large, sensor harness wire is broken, or sensor
harness and body connector are not properly
con-
netted.
r--~- -E-2 When dlagnosls code“15 VEH. SPD. SNSR.” is displayedI[Explanation]
This trouble code is output when there is an
abnormality (other than broken wire or short circuit)
in any of the wheel speed sensor output signals
while driving.
[Hint]
The following can be considered as the cause of the
wheel speed sensor output abnormality.
l Distortion of rotor, teeth missing
lLow frequency noise interference when sensor
harness wire is broken
l Noise interference in sensor signal
lSensor output signal is below the standard value
or amplitude modulation is over the standard
value. Using an oscilloscope to measure the
wave shape of the wheel speed sensor output
signal is very effective.l Broken sensor harness
l Poor connection of connector
NOTE(1) If contact is poor, check the sensor cable by
bending and lightly stretching it.
(2) Except for the case where a fault condition
exists in the system, but the inspection results
are normal; if an abnormality cannot be found in
the sensor circuit displayed as abnormal, erase
the diagnosis code and turn the ignition switch
to OFF once, and then test-drive again.
If the same trouble code is output, replace the
ABS ECU. If the trouble does not occur
any-more, the problem is likely to be with the ABS
ECU.(If the trouble is in the speed sensor circuit, but
is difficult to recreate, it will recur even after the
ABS ECU has been replaced.)
SPEED SENSOR
FRONTCLH) FRONTFTRH)RF.AR(LH) REfIR(RH)
@cTJ @ij@ fi&
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SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-21
Check flow connected with wheelNOTEspeed sensorWhen checking with an oscilloscope, first measure voltage
iivariations in the wheel speed sensor output. (Refer to P.35-57.)
No
Is the resistance value of the wheel
speed sensor part normal?
Standard value:Front 1.4 - 2.2 kRRear 1.3 - 2.1 kSZ
> Malfunction of wheel speed
sensor
Yes
Yes
1
IIs the standard value for
the gap between the wheel
speed sensor and rotor
within the range?
Standard value:;+;;fi3 - 0.9 mm LO12 -
poe288r,$ - 0.7 mm LOO8 -
Yes
I Yes
ICheck the output of each
wheel speed sensor with an
oscilloscope, including the
waveform. (Refer to mea-
surement of wheel speed
sensor output voltage
variations on
P.35-57.)Is the output voltage for
each wheel speed sensor
over the standard value and
is the waveform normal?
:
No-
Lsensor has a poor wave-
form. Replace sensor or
Yes
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SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-27
i-,’
No.
4Trouble condition
IMajor causes
After the ignition key is turned to the
“ON” position, it blinks once and then
illuminates when it is turned to the
“START” position. When the key is
returned to the “ON” position, the light
blinks again. (Blinking with the ignition
key in the “ON” position is synchronized
with operation noise of the valve relay.)
ABSwarrmglightkey ACC.
LOi;+lgmtion14A0593l Break in harness for ECU warning
light drive circuit
l Malfunction of ECU
CONTINUED FROM PREVIOUS PAGE
Yes
Trouble condition
One-sided braking
Insufficient braking force
Decline in ABS function
ABS sometimes functions even when
there is no sudden braking.
(ABSoperation vibration is transmitted.)Remedy
Check, using flow
chart D (Refer to
P.35-37.)Does the ABS warning light illuminate
when starting to drive the car?Trouble with the motor relay, solenoid
valve [due to self test at start-up or
Is there one-sided braking, insufficient
braking force or malfunction of ABSCONTINUED ON NEXT PAGE
Major causes
l Hydraulic line in HU is clogged.
l Mechanical lock of HU solenoid valve
l Hydraulic line in HU is clogged.
l Malfunction in HU solenoid valve
operation
l Insufficient wheel speed sensor out-
put voltage (sensor malfunction, too
large a gap between sensor rotor,
missing rotor teeth)
l Malfunction of ABS ECURemedy
Check HU operation and, if
necessary, replace
HU.If HU is normal, check struc-
tural parts for normal
braking.
Check wheel speed sensor
(Refer to
P.35-57.) and, if
necessary, replace sensor,
adjust gap or replace rotor.
If tests indicate that there are
no mechanical or electrical
failures,replace the ECU.
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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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