1991 MITSUBISHI 3000GT brake rotor

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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[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 - 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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3588SERVICE BRAKES - Wheel Speed Sensor (ABS)WHEEL SPEED SENSOR (ABS)
REMOVAL AND INSTALLATION

a*1. Front rotorFront speed sensor removal steps
2. Clip*I) ++ 3. Front speed sensorw 4. Front speed sensor bracket*I)5. Rear rotorRear speed sensor removal steps
6. Clipa* l + 8. Rearspeedsensor
M350A-B L/ 1
(Refer to Group 42 - Fender.)
14FOO78LJ
Post-installation Operationl Installation of Splash Shield (Front Only)(Refer to Group 42 - Fender.)l Inspection of A.B.S.(Refer to P.35-7.)TSB Revision

L
SERVICE BRAKES - Wheel Speed Sensor (ABS)35-89

12 Nm9 ft.lbs.
6
2
3
12 Nm- 9 ft.lbs.
a*I, Front rotor
Front speed sensor removal steps
2. Clipl * I)*3. Front speed sensora*5. Rear rotorRear speed sensor removal steps
6. Clip
7. Cable band
+I) l *8. Rear speed sensor9. O-ringPre-removal Operation
lRemoval of Splash Shield (Front Only)(Refer to Group 42 - Fender.)1
Post-installation Operationl Installation of Splash Shield (Front Only)(Refer to Group 42 - Fender.)l Inspection of A.B.S.
(Refer to P.35-7.)14FOlOO
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