1991 MITSUBISHI 3000GT engine

35-16SERVICE BRAKES -Anti-lock Braking System Troubleshooting
BABS warning light stays on when the ignition key is in the “ON” position.
[Explanation]
[Hint]
This is the symptom when the ABS ECU does not
Check the diagnosis output and if there is no output
power up due to broken ECU power circuit, etc.,
voltage or if the MUT and ABS ECU cannot
when the fail safe function operates and isolates thecommunicate, there is a good possibility that power
system or when the warning light drive circuit is
is not flowing to the ECU.
short circuited.
!8IGNIISWIT(-
:Et
J’B @
C151
:
E
COMBINATION
METER
-19
7
------____-_---1
2
610 2
~;@lizEFgIIc,
6227J
r bL-1
IN(IGl)
1
,
ig
)
158
7
r-TSB iCaution
lIf the trouble code is output, the system can
be in the fail safe mode. in such a case, erase
the trouble code and then restart the engine
to check if the system is currently in a fault
condition.
~~~~
~~~~1
I,No ,I
Yes6
Replace ECU.
41,No rIDoes the ABS warning light
remain illuminated even with
the HU connector discon-
nected?
Yes
Short-circuit in harness
between HU or ECU and ABS
warning light
> Repair harness or replace
combination meter.
bvision

35-26SERVICE BRAKES -Anti-lock Braking System TroubleshootingI
TROUBLESHOOTING (ABS - AWD)Confirm condition in the following way and diagnosis accordingly.
Does the ABS warning light illuminate as described
below up to the time the engine starts?(2) With the ignition key in the “START” position,
(1) When the ignition key is turned to the “ON”power to the ABS ECU is interrupted and the
position, the ABS ECU causes the ABS warningABS warning light remains lit because the valve
relay is OFF.
light to flash four times in about one second (3) When the ignition key is returned from the
(during which the valve relay self check is made)
and then causes it to go out.“START” position to the “ON” position, the
ABS warning light flashes four times in about
one second (during which the valve relay self
-check is made again) and then goes out.
III
OFFu--I-II
ST
ONACC, LOCK
114A0594Yes
>CONTINUED ON NEXT PAGE
No
No.
Trouble condition
Major causesRemedy
1ABS warning light does not light up at all.l ABS warning light bulb is burnt out.
ACC,LOb--
l Open in ABS warning light electricalCheck, using flowchart A (Refer to
ABScircuit (check for blown fuse)P.35-31.)warningOFFlight
lgmtlon
key
14AO590
2When the ignition key is turned to the
“ON” position, it remains lighted.l Fail safe is functioning due to ECU
self diagnosis.Check, using flowchart B (Refer toABS,“,F
J-l Short in ECU warning light drive circuitP.35-34.)warningl Malfunction of ECUlight
Ignition
key.;i,LOi h
3Does not illuminate when ignition key is
in “START” position.l Malfunction of valve relayl Break in harness between ABS warningCheck, using flowchart C (Refer to
light and HUP.35-36.)l Break in harness between HU andwarning
body ground
TSB Revision1

35-34SERVICE BRAKES -Anti-lock Braking System Troubleshooting
II1
1 B 1 ABS warning light stays on when the ignition key is in the “ON” position.1II\[Explanation]
[Hint]
k.JThis is the symptom when the ABS ECU does not
power up due to broken ECU power circuit, etc.,Check the diagnosis output and if there is no output
when the fail safe function operates and isolates thevoltage or if the MUT and ABS ECU cannot
system or when the warning light drive circuit iscommunicate, there is a good possibility that power
short circuited.is not flowing to the ECU.
IGNITIONSWITCH(IG1)Caution
lIf the trouble code is output, the system can
be in the fail safe mode. In such a case, erase
the trouble code and then restart the engine
to check if the system is currently in a fault
condition.
f
j @
?
j 0
:ml-
I2a-----11 g:I aI7
:I1
-_307a
-
I-=_-. -----------1
P
Y
4 a:&
I25ABS
ECU
iz- 11213 ia1516j7j819~10~11~12~13~14~15~16~17~1819l20l21C2C3Ca~25~~7~3~29~0~1~32~3~35
:95-AK-R9502
4
Replace ECU.
I YesI.
Replace HU or replace
valve relay.
I
_
ai.. .
ITSB hevIsIon

SERVICE BRAKES - Set-vice Adiustment Procedures35-45lUF51F
Pedal
7\ \!4FOO7.
F14511
F14519
TSB Revision-_.1
SERVICE ADJUSTMENT PROCEDURES
BRAKE PEDAL INSPECTION AND ADJUSTMENT
1.Measure the brake pedal height as illustrated. If the’brakepedal height is not within the standard value, adjust as
follows.
Standard value (A): 177
- 182 mm (7.0 - 7.2 in.)
(I) Disconnect the stop light switch connector, loosen the
lock nut, and move the stop light switch to a position
where it does not contact the brake pedal arm.
(2) Adjust the brake pedal height by turning the operating
rod with pliers (with the operating. rod lock nut
loosened), until the correct brake pedal height is
obtained.
(3) After screwing in the stop light switch until it contacts
the brake pedal stopper (just before the brake pedal is
caused to move), return the stop light switch
l/2 to 1
turn and secure by tightening the lock nut.
(4) Connect the connector of the stop light switch.
(5) Check to be sure that the stop light is not illuminated
with the brake pedal unpressed.
Reference value (6): 0.5
- 1.0 mm (.02 - .04 in.)
2. On vehicles with automatic transaxle, check the shift-lock
mechanism. (Refer to GROUP 23
- Transaxle Control.)
3. With the engine stopped, depress the brake pedal two or
three times. After eliminating the vacuum in the power
brake booster, press the pedal down by hand, and confirm
that the amount of movement before resistance is met (the
free play) is within the standard value range.
Standard value (C): 3
- 8 mm (.I - .3 in.)
If the free play is less than the standard value, confirm that
the clearance between the stop light switch and brake
pedal is within the standard value.
If the free play exceeds the standard value, it is probably
due to excessive play between the clevis pin and brake
pedal arm. Check for excessive clearance and replace faulty
parts as required.
4.Start the engine, depress the brake pedal with approximate-
ly 500 N (110
Ibs.) of force, and measure the clearance
between the brake pedal and the floorboard.
Standard value (D): 80 mm (3.1 in.) or more
If the clearance is less than the standard value, check for air
trapped in the brake line and for brake fluid leaks. If
necessary, check the brake system mechanism (excessive
shoe clearance due to faulty auto adjuster) and repair faulty
parts as required.~1~1
I
I
I
I
I

35-46SERVICE BRAKES - Service Adjustment Procedures
BRAKE FLUID LEVEL SENSOR CHECK
I
MBSFBAF
Good
k‘14UOO61
When engine is
stoppedNo good
When engine isstarted
14UOO6C)Checkvalve/1. Connect a circuit tester to the brake fluid level sensor.
I
2.Move the float from top to bottom and check for continuity.
3. The brake fluid level sensor is in good condition if there is
‘k&Jno continuity when the float surface is above “A”, and if,there is continuity when the float surface is below “A”.
BRAKE BOOSTER OPERATING INSPECTION
M35FCAOFor simple checking of brake booster operation, carry out the
following tests.
1.Run the engine for one or two minutes, and then stop it.
2. Step on the brake pedal several times with normal
pressure.If the pedal depresses fully the first time but gradually
becomes higher when depressed succeeding times, the
booster is operating properly.
If the pedal height remains unchanged, the booster is
faulty.
3. With the engine stopped, step on the brake pedal several
times with the same pressure to make sure that the pedal
height will not change.
Then step on the brake pedal and start the engine.
If the pedal moves downward slightly, the booster is in
good condition. If there is no change, the booster is faulty.
4.With the engine running, step on the brake pedal and then
stop the engine.
Hold the pedal depressed for 30 seconds. If the pedal
height does not change, the booster is in good condition. If
the pedal rises, the booster is faulty.
If the above three tests are okay, the booster performance can
be determined as good.
If one of the above three tests is not okay at last, the check
valve, vacuum hose, or booster will be faulty.
CHECK VALVE OPERATION CHECKM35FNALWhen checking the check valve, keep the check valve fit in the
vacuum hose.
1. Remove the vacuum hose.
Caution
The check valve is press-fit inside the vacuum hose and
do not remove the check valve from the vacuum hose.1
d~
TSB Revision

35-48SERVICE BRAKES - Service Adjustment Procedures
BLEEDINGCautionM35FYAOUse the specified brake fluid. Avoid using a mixture of the
specified brake fluid and other fluid.
Specified brake fluid: Conforming to DOT314POO3C
1
14A045
When new
When wornWear
indicator
Lrakedisc
indicatorBrake
disc
14FOO4CBLEEDING THE MASTER CYLINDER
If the master cylinder is empty of brake fluid, bleed the cylinder
as follows.
(1) Fill the reserve tank with brake fluid.
(2) Depress and hold the brake pedal.
(3) Let your fellow worker plug the master cylinder outlet with
finger.
(4) Keeping the condition (3), release the brake pedal.
(5) Repeat steps
(2) to (4) three to four times while filling the
master cylinder with brake fluid.
BLEEDING THE BRAKE PIPE LINE
Bleed the brake pipe line with the engine running in the order
shown in the illustration.
Caution
When adding brake fluid on vehicles with ABS, be sure to
fit the filter to the reserve tank.
FRONT DISC BRAKE PAD CHECK AND REPLACE-
MENTM35FQAG
NOTEThe brake pads have wear indicators that contact the brake disc
when the brake pad thickness becomes 2 mm
(.079 in.), and
emit a squealing sound to warn the driver.
&ionI

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.