1991 MITSUBISHI 3000GT Service Manual

SRS ServicePrecautions /SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Spectiications52B-15View A
To front impact sensor
(L.H.)
\To frontimpactsensor (R.H.)
\To body wiring harness (14-pin)To clock spring19FOllOZ-pin blue connector to
right front impact sensor
Z-pin yellow connector
to left front impact sen2-pin red corm
to clock spring
SDU
14-pin red connector to body wiring harness
j.SRS components should not be subjected to heat over 93°C (2OO”F), so remove the front impact sensors,
SRS diagnosis unit and air bag module and clock spring before drying or baking the vehicle after painting.
Recheck SRS system operability after re-installing them.
j. Whenever you finish servicing the SRS, check the SRS warning light operation to make sure that the
system function properly. (Refer to
P.52B-2.)
7. In case of any questions about the SRS, call the regional Tech Line at I-800-446-6064.
NOTESERIOUS INJURY CAN RESULT FROM UNINTENDED AIR BAG DEPLOYMENT, SO USE ONLY THE
PROCEDURES AND EQUIPMENT SPECIFIED IN THIS MANUAL.
SPECIFICATIONSMUCB-B
SERVICE SPECIFICATION
ItemsSpecification
Standard value
Front impact sensor resistanceQ2,000 f 40
TSB Revision

52B-16 SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - SRS Sewice Pre=utions
TEST EQUIPMENT TO BE USED FOR TROUBLESHOOTINGM52DA-0
heck harness is used on various
(connected
3R resistor)Use a multwneter for which the
lessat themnmumrange ofreslstance measurement
1 TSB Revision1

SUPPLEMENTAL RESfRAlNT SYSTEM (SRS) - Troub!eshooting 52B-17TROUBLESHOOTING
M52ECAA
idSRS DIAGNOSTIC PROCEDURES
- INITIAL STEPS’FOLLOW THESE STEPS WHEN BEGINNING ANY SRS SERVICE:
/II/ ,- -u’ 16FO304
SRS warning light
Multi-use fester
(MB991341)RbM pack(MB991359)
Diagnosis/
service data
output
Ground
16LOO9
[TSB
1. Check the SRS fuses (multi-purpose fuses No. 11 and No.
18).If either is loose, tighten it; if damaged or blown, replace it.
.
2.After performing step 1, start engine. Does “SRS” warning
light
illumi.nate for about 7 seconds and then turn OFF? If
yes, SRS system is functioning properly.
If no, continue with following steps.
NOTEIf the battery power supply (multi-purpose fuses No. 11 or
No. 18) is disconnected with the ignition key in the “ON”
position, the SRS warning light will continue to illuminate
even after the fuses are replaced in their original positions.
In this case, the SRS warning light can be extinguished by
turning the ignition switch ON and OFF
10 times.
3. Turn the ignition key to the “LOCK” position.
4. Insert ROM pack into the Multi-use Tester and connect
tester to Diagnosis Check Connector in glove compart-
ment.
5. Start the SRS diagnosis,by conducting TEST 1
(SRSwarninq liqht does not extinguish) or TEST 2 (SRS warning
light does- not illuminate.) which begins on next page or
page
[52B-191.
ivision

52B-18 SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Troubleshooting
DIAGNOSTIC SEQUENCE
TEST 1SRS WARNING LIGHT DOES NOT EXTINGUISH
\1 I
Vehicle Model Selection
{
F
1. SELF-DIAG CODE2. SERVICE DATA
3. ACTUATOR TEST
4. SPECIAL TEST
,, I,
0
“CLEAR” and“4”1.
SIMLTD VEH SPD
2. PULSE CHK
3. DRIVE RECORDER4. EXTERNAL COMM
” 1 ”
1’1
y,,
SRS-AIR BAGID NO.: 19INPUTABOVE CODE
I(1) Turn the ignition key to the “ON” position.
(2) The Multi-use Tester display section successfully passes
the self-check and the model selection menu is displayed
after completing the self-check of the Multi-use Tester.
Select 3000GT 91 MDL [No. 3 (Non-Turbo) or No. 4 (Turbo)]
and SRS-AIR BAG system by entering the “YES” key.
(3) If the Multi-use Tester displays “CAN’T COMM.“, check
the Multi-use Tester and vehicle side self-check diagnosis
TSB Revisionconnector for poor connections (Refer to the previous
page.) and perform
[I.If the 3000GT 91 MDL SRS-AIR BAG system selection is
successful, continue with following steps.
(4) Select the “1. SELF-DIAG CODE” function and read (and
write down) all displayed diagnosis codes.
(5) Press the “CLEAR” key to return to the Function Selection
and select the
“4. SPECIAL TEST”.
(6) Pr+FE,the ”
1 ” key and select the “5. ERASE DIAG.
(7) Erase the diagnosis codes following the Multi-use Tester
messages.
(8) Start engine.
Does “SRS” warning light illuminate for about 7 seconds,
turn OFF and then remain extinguished for at least 45
seconds?
If yes, SRS system is functioning properly now.
If no, check the diagnosis codes written down at step (4)
above, refer to SELF-DIAGNOSIS QUICK REFERENCE
CHART
(P.52B-20) and perform service indicated there.

SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Troubleshooting 52B-19
TEST 2SRS WARNING LIGHT DOES NOT ILLUMINATE
Vehicle Model Selection
-
pc-y-y
1. SELF-DIAG CODE
2. SERVICE DATA
3. ACTUATOR TEST
4. SPECIAL TEST
(1) Turn the ignition key to the “ON” position.
(2) The Multi-use Tester display section successfully passes
the self-check and the model selection menu is displayed
after completing the self-check of the Multi-use Tester,
select 3000GT 91 MDL [No. 3 (Non-Turbo) or No. 4 (Turbo)]
and SRS-AIR BAG system by entering the “YES” key.
(3) If the Multi-use Tester displays “CAN’T COMM.“, check
the Multi-use Tester and vehicle side self-check diagnosis
connector for poor connections (Refer to
P.52B-17.) and
perform
ITEST 4 1.If the 3000GT 91 MDL SRS-AIR BAG svstem selection is
successful, continue with following steps.
(4) Select the “1. SELF-DIAG CODE” function and read (and
write down) all displayed diagnosis codes.
(5) Check diagnosis codes against SELF-DIAGNOSIS QUICK
REFERENCE CHART and perform service indicated there.
TSB Revision1

52B-20 SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Troubleshooting
SELF-DIAGNOSIS QUICK REFERENCE CHART
Fault
No.
-
11
32
Diagnosis code name
[Failure mode]
(NORMAL)
G-SENS. TRBL
1[Short circuit]
G-SENS. TRBL 2[One open-circuit]
G-SENS. TRBL 3[Two open-circuit]
SQUIB TRBL 1[Short circuit]
SQUIB TRBL 2
[Open-circuit]
CONDENS. VO. HI
CONDENS. VO. LO
CRANKING TRBL
CONN. UNLOCKED
Explanation
Normal. The SRS is in goodorder.
The circuits for the front impact sensor are shortedto each other.
Right or left impact sensor cirucit is open or the
wire from the sensor to the SDU is open-circuit.
Right and left impact sensor circuits are open or thewires from the sensors to the SDU areopen-circuit.
The circuits for the air bag module (squib) are
shorted to each other or the circuit isgrounded.
The air bag module Isquib) circuit is open or the wire
from the air bag to the SDU (clock spring) is open-circuit.
The capacitor (integrated in the
SDU) terminal voltage
is higher than the specified value for 5 seconds.
The capacitor (integrated in the
SDU) terminal voltage
is lower than the specified value for 5 seconds.
The circuit for the cranking signal is shorted to
some power supply circuits.
It takes at least 45 seconds that the SDU detects
this fault.
The lock switch (short bar) of the SDU double lockconnector isopen.Service
Perform TEST 5
Perform TEST 6(I) Turn the ignition key
to the “LOCK” posi-
tion, disconnect the
negative battery
cable and tape the
terminal.
(2) After waiting atleast 30 seconds,
replace the SDU.
(Refer to P.52B-59.)
Perform TEST 7
Perform TEST 8NOTE
- IMPORTANT
(1) After repairing the SRS, reconnect the battery cable, erase the diagnosis code memory from theMulti-use Tester and check the SRS warning light operation to verify the system functions
properly. (Refer to TEST 1.)
(2) SDU
= SRS Diagnosis Unit
1 TSB Revision

SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Troubleshooting 52B-21
/
id
FaultDiagnosis code nameNo.[Failure mode]Explanation
Service
41
IG VOLT LOW 1The multi-purpose fuse (No. 18) is blown or the wirefrom the fuse to the SDU is open-circuit or itsresistance value is increased.
It takes at least 5 seconds that the SDU detects
this fault.
Perform TEST 9
42
IG VOLT LOW 2The multi-purpose fuse (No. 11) is blown or the wirefrom the fuse to the SDU is open-circuit or itsresistance value is increased.
It takes at least 5 seconds that the SDU detects
this fault.
Perform TEST 10
SRS LMP TRBL 1
i
The SRS warning light circuits are open or the wireWhen SRS warning lightOpen circuit orfrom the light to the SDU is grounded.does not extinguish:43ground shortIIt takes at least 5 seconds with the light OFF thatPerform TEST 11the SDU detects this fault.When SRS warning light
does not illuminate:
Perform TEST 12
SRS LMP TRBL 2The SRS warning light drive transistor (integrated
(1) Turn the ignition key
44SRS warning light
[I
in the SDU) is open-circuit.to the “LOCK” posi-
drive transistortion, disconnet the
is open-circuitnegative battery
cable and tape the
SRS DIAG. UNITThe EEP ROM or A/D converter (integrated in the SDU)terminal.is defective.(2) After waiting at
45least 30 seconds,
replace the SDU.
(Refer to P.52B-59.)
/NOTE -IMPORTANT
b(1) After repairing the SRS, reconnect the battery cable, erase the diagnosis code memory from theMulti-use Tester and check the SRS warning light operation to verify the system functions
properly. (Refer to TEST 1.)
(2) SDU
= SRS Diagnosis Unit
1 TSB Revision

52B-22 SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Troubleshooting
TEST 3NO COMMUNICATION BETWEEN MULTI-USE TESTER AND SDU
(SRS warning light does not extinguish)
COMBINATION METER(SRS WARNING LIGHT)
SRS DIPGNOSIS UNITSRS
diag(osis unit
View A13R0704To front impact sensor
(L.H.)
\To front impact sensor (R.H.)To
clock springI19FOllO
To body wiring harness (14-pin)
13R072113RO72:L
A double-lock mechanism is employed for the connec-
tor of the SRS diagnosis unit, so care must be taken notto damage it by using excessive force or by not
. .disconnecting it correctly.(4) Disconnect the red
IQpin connector from the SRS diagno- Q’sis unit while pressing down the lock of the connector.
(Refer to
P.52B-9.)
TSB Revision
(1) Turn the ignition key to the “LOCK” position, disconnect
the negative battery cable and tape the terminal.
Caution
Wait at least 30 seconds after disconnecting the battery
cable before doing any further work. The SRS system is
designed to retain enough voltage to deploy the air bagfor a short time even after the battery has been
disconnected, so serious injury may result from unin-
tended air bag deployment if work is done on the SRSsystem immediately after the battery cable is discon-
nected.(2) Remove the rear console assembly. (Refer to GROUP 52A
- Floor Console.)
(3) Use a screwdriver to push in the lock spring of the lock
lever of the SRS diagnosis unit to unlock the lock lever.
Caution
d
I
I
I1
LJ
I
I
I
I
I