1991 MITSUBISHI 3000GT lock

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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SERVICE BRAKES -Anti-lock Braking System Troubleshooting
1 CONTINUED FROM PREVIOUS PAGE 1
IAfter a test drive, use self diagnosis to
check (Refer to
P.35-29.).
INo trouble codes output and normal
codes are displayed?NoNo diagnosis output
NoTrouble codes are output
Yes
All ABS functions are normal.
(Nor are there stored memory of
past trouble code.)
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SERVICE BRAKES -Anti-lock Braking System Troubleshooting
MUT
I/(MB991 341)
\03A0211
DIAGNOSIS CODE CHART
I I21G SNSR.IE-3
[ 22 1 STOP LAMPSW 1E-4
CHECK USING SELF DIAGNOSIS FUNCTION
(1) With the ignition switch OFF, connect the MUT through the
adapter harness (MB991377). turn the ignition ON and
select the ABS system. (The ABS warning light lights up, it
goes into the MUT mode. In the MUT mode, ABS does
not function.)
If it does not go into the MUT mode, check the ECU power
circuit and the harness between the ECU and diagnosis
check terminals.
(2) Read the diagnosis output codes from the ECU memory.
(3) Clear the diagnosis codes once from memory. (Refer to
P.35-30.)If the memory cannot be cleared, the ECU is currently
detecting the trouble and the ABS ECU is in fail safe. If it
can be cleared, the trouble is either temporary or appears
only when driving.
(4) When the trouble codes cannot be cleared, or when the
ABS ECU goes into fail safe during another test drive and
trouble codes are output, check according to trouble code
check charts (E-l-E-7).
Reference
we -1 ;+EiT;
I I41FR SOL. VALVEI
P.35-381 ;; / ;;tS;L;;;E/ E-5
I I51VALVE RELAY
P.35-38 1 52 1 MOTOR RELAY)E-7
si 55 / ‘ONT. UNlT/ replaEcCeUment
Reference
iwe
P.35-42
P.35-43
P.35-44
-
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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
1 TSB Revision

SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-31
L’A ABS warning light does not light at all.
[Explanation][Hint]
When it does not light up at all, there is a strongIf other warning lights do not light up either, fuse is
possibility that there is trouble with ABS warningprobably blown.
light or with power to the light.
FUSIBLE LINEI
L--L5--
i
IGNITIONSWITCH(IG2)IGNITIONSWITCH(IG1)
(L-R)-' .3
G-RI
7
!
m59COMBINATION
iMETER
1:I1o‘r_- ----- ‘2 -- ‘Ti----‘%--‘79 -_----- -7 -- “j-+3 -----1
=p!Rq3;
g:W
25
b
ABS-ECU
n=
1 TSB Revision

35-32SERVICE BRAKES -AniLlock Braking System Troubleshooting
NoWith the ignition key in the “ON” posi-
I--Check fuse No. 11. If it is
blown, correct the cause of
the blown fuse and then
replace the fuse.J
Yes
I
( ~;T&$Efg,?~ )harness connector terminal
No. 59 and ground indicate
battery voltage?
----F--
&Repair harness.
Circuit in combination meter
-is broken.
Is there continuity between combination
meter No. 58 and No. 59 terminals?
Are instrument panel wiring harness
and body wiring harness connected
Broken wire in ECU, valve relay or both
drive circuits. Check both circuits.
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SERVICE BRAKES -Anti-lock Braking System Troubleshooting35-33
1i, 1 CheckABSECU. ,
Remove the ECU connector and
check.Does the voltage between ECU harness
> Broken wire between ABSj Repair harness.
connector terminal No. 25 and ground
warning light and ECU
indicate battery voltage while the
ignition key is in the “ON” position?
Yes
> ABS ECU malfunction> Replace ABS ECU.
Remove valve relay and check.
I
1Nois valve relay normal? (Refer to
P.35-62.)) Valve relay malfunction+ Replace valve relay.IYes
Install the valve relay, remove the HU
connector and check.
Does voltage between the HU harness
uLEm-h[ Repair harness.
connector terminal No. 8 and ground
indicate battery voltage
while the
ignition key is in the “ON” position?
Yes
r7; t%$~?$!Je~~~g~undIIs there continuity between HU harness9 Repair harness.
connector terminal No. 9 and ground?
Is there continuity between HU harness
connector terminals No. 8 and No. 9?Yes+ HU malfunctionI+ Replace HU.
b Connector not connected
securely.- Replace connector.
1 TSB Revision

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