check engine MITSUBISHI 3000GT 1991 Service Manual

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
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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-39
MB991349SRS Check Harness
connector
View ASRS Check Harness connector @
Ground
II No(5) Connect the now disconnected red harness-side SDU
connector
(14-pin) to the connector @ of the SRS Check
Harness.(6) Check according to the flow chart below, using the digital
multi-meter.
IIIIs there continuity between the No. 191 or No. 20 terminal ofi;RSCheck‘1 ~~~~~;,0~~~~~~.~~~-14.~r1 Ground ‘jrcuit Open1Harness connector @ and ground?
Reconnect negative terminal of
(()
terminal (of SRS Check Harness connec-
tor 0) and the No. 19 or 20 terminal(ground) indicate system voltage?NOTE
- IMPOR
TANT
Yes
(1) Turn the ignition key
to the “LOCK” po-
sition, disconnect
the negative battery
cable and tape the
terminal.
(2) After waiting at least30 seconds, replacethe SDU.(Refer toP.52B-59.)
(1) Turn the ignition key
to the “LOCK” po-
sition, disconnect
the negative battery
cable and tape theterminal.
(2) After waiting at least
30 seconds, repair orreplace the body wir-ing harness. (Refer toP.52B-14.)
(1) If more than 45 seconds of cranking is required to start up the engine, the diagnosis code will be
stored in memory, but if there is no problem, the diagnosis code will be cleared and the SRS willreturn to normal.
(2) 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.)
(3) SDU
= SRS Diagnosis Unit
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SUPPLEMENTAL RESTRAINT SYSTEM (SRS) - Z~-%Z%&Z% 528-49Manufacture
date
IVEHICLE TYPE: PASSENGER CAR
MU9001/
OOFOOOlSRS
warnmq light- -SDU’
t>19FOlO:SRS MAINTENANCE AND
POST-COLLISION DIAGNOSIS
M52PCAAMAINTENANCE
The SRS must be inspected by an authorized dealer
10 years
after the car manufacture date shown on the certification label
located on left front door latch post.
Maintenance Items
1.“SRS” WARNING LIGHT CHECK
When the ignition key is turned to “ON” or engine started,
the “SRS” warning light will illuminate for about 7 seconds
and then turn off.
This means that the system is functioning properly.
2. SRS COMPONENTS VISUAL CHECK
(1) Turn the ignition key to the “LOCK” position, discon-
nect the negative battery cable and tape the terminal.
CautionWait at least 30 seconds after disconnecting the
battery cable before doing any further work. The
SRS system is designed to retain enough voltage todeploy the air bag for a short time even after the
battery has been disconnected, so serious injury
may result from unintended air bag deployment
if
work is done on the SRS system immediately afterthe battery cable is disconnected.
(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.
CautionA double-lock mechanism is employed for the
connector of the SRS diagnosis unit, so care must
be taken not to damage it by using excessive forceor by not disconnecting it correctly.
(4) Disconnect the red
14-pin connector from the SRS
diagnosis unit while pressing down the lock of the
connector. (Refer to
P.52B-9.)
13R0721113R0722
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55-1
HEATER, AIR
CONDITIONER
AND VENTILATION
CONTENTSM55AA- -
HEATERS AND AIR CONDITIONING................3HEATER UNIT*........................................................................22
SPECIFICATIONS
....................................................................3REFRIGERANT LINE................................................................35General Specifications
........................................................3RESISTOR................................................................................20Lubricants
............................................................................4SAFETY PRECAUTIONS........................................................9Sealant and Adhesive............................................................4
Service Specifications3SERVICE ADJUSTMENT PROCEDURES............................10........................................................
SPECIAL TOOLS4Charging Procedures............................................................11
i
........................................................................Charging the Refrigerant....................................................12Compressor Drive Belt Adjustment....................................11
HEATERS AND MANUAL AIR CONDITIONER5Compressor Noise................................................................16
................................................16
AIR CONDITIONER SWITCH................................................21Handling Tubing andFittings
Idle-up Operation Check....................................................17
BELT LOCK CONTROLLER20Performance Test................................................................15....................................................
BLOWER ASSEMBLYPower Relay Check............................................................17............................................................23Refrigerant Leak Repair Procedure....................................15COMPRESSOR........................................................................
27TestProcedures....................................................................10
CONDENSER AND CONDENSER FAN MOTOR................33TROUBLESHOOTING............................................................5
ENGINE COOLANT TEMPERATURE SWITCH....................
39VENTILATORS (AIR INLET AND AIR OUTLET)................38
EVAPORATOR
........................................................................
25VENTILATORS (INSTRUMENT PANEL)*............................36
HEATER CONTROL ASSEMBLY*
........................................18CONTINUED ON NEXT PAGE
SUPPLEMENTAL RESTRAINT SYSTEM (SRS)
(1)A Supplemental Restraint System (SRS), which uses a driver-side air bag, has been installed in the 3000GT.(2)The SRS includes the following components: impact sensors, SRS diagnosis unit: SRS warning light, air bagmodule, clock spring, interconnecting wiring. Other SRS-related components (that may have to be
removed/installed in connection with SRS service or maintenance) are indicated in the table of contents byan asterisk (*).
WARNING!(1)Improper service or maintenance of any component of the SRS, or any SRS-related component, can lead to
personal injury or death to service personnel (from inadvertent firing of the air bag) or to the driver (fromrendering the
SRS inoperative).(2) Service or maintenance of any SRS component or SRS-related component must be performed only at anauthorized MITSUBISHI dealer.
(3) MITSUBISHI dealer personnel must thoroughly review this manual, and especially its GROUP 52B
-Supplemental Restraint System (SRS), before beginning any service or maintenance of any component of theSRS or any SRS-related component.

55-10 HEATERS AND MANUAL AIR CONDITIONER -Service Adjustment Procedures
OFF-----__-__1210235 2,1002,700
(30) (33)(299) (384)
Pressure Fil
2OPOOlL
SERVICE ADJUSTMENT PROCEDURES
M55FEAU
TEST PROCEDURESSIGHT GLASS REFRIGERANT LEVEL TEST
The sight glass is a refrigerant level indicator. To check the
refrigerant level, clean the sight glass and start the vehicle
engine. Push the air conditioner button to operate the com-
pressor, place the blower switch to high and move the
temperature control lever to MAX. COOL. After operating for a
few minutes in this manner, check the sight glass.
(I) If the sight glass is clear, the magnetic clutch is engaged,
the compressor discharge line is warm and the compressor
inlet line is cool; the system has a full charge.
(2) If the sight glass is clear, the magnetic clutch is engaged
and there is no significant temperature difference between
compressor inlet and discharge lines; the system has lost
some refrigerant.
(3) If the sight glass shows foam or bubbles, the system could
be low on charge. The system has to be charged with some
refrigerant.
MAGNETIC CLUTCH(1) Disconnect the wiring to the magnetic clutch.
(2) Connect battery (+) voltage directly to the wiring for the
magnetic clutch.
(3) If the magnetic clutch is normal, there will be a “click”. If
the pulley and armature do not make contact (“click”), there
is a malfunction.
v):
I
I
I
I
\,
3’
RECEIVER DRIERTo Test the Receiver Drier
(1) Operate the unit and check the piping temperature by
touching the receiver drier outlet and inlet.
(2) If there is a difference in the temperatures, the receiver
drier is restricted.
Replace the receiver drier.
DUAL PRESSURE SWITCH (LOW PRESSURE SWITCH)
(I) Turn back the adaptor valve handle all the way and install it
to the low pressure side service valve.
(2) With the gauge manifold low pressure service valves
closed, connect the gauge manifold high pressure side
charging hose to the adaptor valve.
(3) Tighten the adaptor valve handle and open the service
valve.
(4) If there in continuity between the dual pressure switch
terminals when the low pressure side pressure is at the
level of dual pressure switch ON condition shown to the
left, the switch is functioning normally. If not, replace the
L/(switch.
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CautionRefrigerantR-l 2iAdaptorNever use the high pressure side as this may cause
/valve
refrigerant to flow back, using rupture of the servicecan.(7) Start the engine. Charge valvergmg hose
55-14 HEATERS AND MANUAL AIR CONDITIONER - Service Adjustment procedures
CORRECTING LOW REFRIGERANT LEVEL
(I) Install the charge valve to the service can with its handle
turned back all the way.
(2) Connect the charging hose to the charge valve.
(3) Connect the adaptor valve to the charging hose with itsL&lhandle turned back all the way.
(4) Tighten the charge valve handle to puncture the can.
(5) Operate the adaptor valve handle to bleed air.
(6) Install the adaptor valve to the low pressure side service
valve.
(8) Operate the air conditioner and set at the lowest tempera-
ture (MAX. COOL).
(9) Fix the engine speed at 1,500 rpm.
(10)Open the adaptor valve and charge refrigerant checking
level with the sight glass.
(1 l)Upon completion of charging, close the adaptor valve and
20M0128charge valve.
(12)Remove the adaptor valve from the service valve.
NOTEIf the service can is not emptied completely, keep the
charge valve and adaptor valve connected to the can for
next charging.
Adaptor
valve
\
DISCHARGING SYSTEMUse the refrigerant recovery unit to discharge refrigerant gas
from the system.
NOTERefer to that Refrigerant Recovery and Recycling Unit Instruc-
tion Manual for operation of the unit.
REFILLING OF OIL IN THE AIR CONDITIONER SYSTEM
Too little oil will provide inadequate compressor lubrication and
cause a compressor failure. Too much oil will ,increase
discharge air temperature.
When a
FX-105VS compressor is installed at the factory, it
contains
160 cc (9.8 cu.in.) of refrigerant oil. While the air
conditioning system is in operation, the oil is carried through
the entire system by the refrigerant.
Some of this oil will be trapped and retained in various parts of
the system.
When the following system components are charged, it is
necessary to add oil to the system to replace the oil being
removed with the component.
Condenser: 8 cc
(5 cu.in.)Evaporator: 72 cc (4.4
cu.in.)Piping: 9.6 cc
(6 cu.in.)Receiver drier: 6.4 cc
(.4 cu.in.)
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L/
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HEATERS AND MANUAL AIR CONDITIONER -Service Adjustment Procedures 55 15
PERFORMANCE TESTM55FWAH
(I) Park the tested vehicle at the area which is not exposed to
the direct sunlight.
(2) Connect a tachometer.
(3) Turn back the adaptor valve handle all the way and install
the adaptor valves to the high pressure and low pressure
service valves.
(4) Connect the gauge manifold to the adaptor valves.
(5) Tighten the adaptor valve handle and open the service
valves.
(6) Start the engine.
(7) Set the controls to the air conditioner as follows:
Air conditioning switch: Air conditioner
- ON position
Mode selection: Face position
Temperature control: MAX. COOL position
Air selection: Recirculation position
Blower switch: HI (Fast) position
(8) Adjust engine speed to 1,000 rpm with air conditioner
clutch engaged.
(9) Engine should be warmed up with doors, windows close,
and hood open.
(1O)lnsert a thermometer in the center air conditioner outlet and
operate the engine for 20 minutes.
(II )Note the discharge air temperature.
NOTEIf the clutch cycles, take the reading before the clutch
disengages.
Performance Temperature ChartGarage
amb;in,L;am-perature21 (70)
26.7 (80)32.2 (90)37.8 (100)43.3 (110)
Iperature Dischargeair "C tem- ("F)(32.0 0.0- -3.0 37.4)(33.8 1.0- -4.0 39.2)(33.8 1.0- -4.0 39.2)(33.8 1.0- -4.0 39.2)(35.6 2.0- -41.0) 5.0
ICompressor pressure kPa discharge (psi)(98.1 690- -105.3) 740(110.9 780- -830 118.1)(123.7 870- -920 130.9)(153.6 1,080- -1,130 160.7)(172.1 1,210- -1,260 179.2)Compressor suction130
-190130-190130-190130-190130-190
pressure kPa (psi)(18.5-27.5)(18.5-27.5)(18.5-27.5)(18.5-27.5)(18.5-27.5)
REFRIGERANT LEAK REPAIR PROCEDUREM55FHAQ
LOST CHARGEIf the system has lost all charge due to a leak:
(1) Evacuate the system. (See procedure.)
(2) Charge the system with approximately one pound of
refrigerant.
(3) Check for leaks.
(4) Discharge the system.
(5) Repair leaks.
(6) Replace receiver drier.
Caution
Replacement filter-drier units must be sealed while instorage. The drier used in these units will saturate
water quickly upon exposure to the atmosphere. When
installing a drier, have all tools and supplies ready forquick reassembly to avoid keeping the system open
any longer than necessary.(7) Evacuate and charge the system.
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HEATERS AND MANUAL AIR CbNDlTlONER -Service Adjustment Procedures 55 17
ADJUSTMENT PROCEDURES(1) Select a quiet area for testing. Duplicate conditions as much
as possible. Switch compressor on and off several times to
clearly identify compressor noise.
To duplicate high ambient conditions (high head pressure),
restrict air flow through condenser. Install manifold gauge
set to make sure discharge pressure doesn’t exceed 2,070
kPa (300 psi).
(2) Tighten all compressor mounting bolts, clutch mounting
bolt, and compressor drive belt. Check to assure clutch coil
is tight (no rotation or wobble).
(3) Check refrigerant hoses for rubbing or interference that can
cause unusual noises.
(4) Check refrigerant charge. (See “Charging System”.)
(5) Recheck compressor noise as in Step 1.
(6) If noise still exists, loosen compressor mounting bolts and
retorque. Repeat Step 1.
(7) If noise continues, replace compressor and repeat Step 1.
POWER RELAY CHECKMBBFNAK(1) Remove the radiator fan motor relays (HI) and (LO) from the
relay box on the right of the engine compartment.
(2) Remove the radiator fan motor relay (air conditioner),
condenser fan motor relays (HI) and (LO), and
air-conditioner compressor relay from the relay box on the left
of the engine compartment.
(3) Remove the blower motor relay from the junction box.
(4) Remove the blower motor HI relay from the blower case
assembly.
(5) Check the continuity between terminals using a circuit
tester.
J Blower m.otor HI relay\2OFOO6l
IDLE-UP OPERATION CHECKM55FOAB
(1) Before inspection and adjustment set vehicle in the
following condition:
lEngine coolant temperature: 80 - 95°C (176 - 203°F)
lLights, electric cooling fan and accessories: Set to OFF
l Transaxle: Neutral (N or P for vehicles with
A/T)l Steering wheel: Straightforward
(2) Check to be sure that the idling speed becomes the
standard value when the air conditioner switch is switched
ON and the air conditioner is activated.
Standard value: 900
+ 100 rpm
NOTEThere is no necessity to make an adjustment, because the
idling speed is automatically adjusted by the ISC” system.
If, however, there occurs a deviation from the standard
value for some reason, check the ISC” system.
ISC: Idle Speed Control
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HEATERS AND MANUAL AIR CONDITIONER - Compressor
Spring
Valve
ompressor
2OPO286~
SERVICE POINT OF DISASSEMBLYMSlSFAE3. REMOVAL OF NUT
Use the special tool to loosen the nut,
INSPECTIONM55SGABl Check the surface of the armature for scoring or bluing.
l Check the surface of the rotor for scoring or bluing.
l Check the sealing surfaces for cracks, scratches and
deformation.
0Check the front housing for cracks or scoring on the sealing
surfaces.l Check the compressor shaft for scoring.
J
HIGH PRESSURE RELIEF VALVE CHECK
The high pressure relief valve is a safety feature which releasesI
part of the refrigerant inside the system into the atmospherewhen the high pressure level exceeds 3,550
kPa (505 psi)
during air conditioner operation.Once the pressure inside the system has been reduced to
2,400
kPa (341 psi) or lower, the high pressure relief valveL&Jcloses, thus allowing continued operation.
(1) If a leak is detected at section A, replace the high pressure
relief valve. The valve can be used unless there is a leak(from that section.
(2) If a leak is detected at section B, retighten the valve. If the
leak still persists after retightening the valve, replace the
packing.
THERMOSTAT CHECK
(1) Dip the thermostat in engine oil.
(2) Check for continuity across terminals @ and @ when theengine oil is heated.
Standard value:Continuity at approx.
110°C (230°F) or less
at A pointNo continuity at approx. 155°C (311°F) or more
,I
at B pointII;TSB Revision

HEATERS AND MANUAL AIR CONDITIONER - Compressor55-3120N003d
2OFOO96
I
Ec-3
3180?+I! (25)zz
h34\
*
Engine speed rpm2OPO2S
\CrankshaftTapered part
20A0157
REVOLUTION PICK UP SENSOR CHECKMeasure the resistance between terminals
@ and @ of the
connector.
Normal resistance: 405 + 35 R when ambient temperatureis
20°C (68°F)
If the measurement deviates greatly from the above resis-
tance, replace the revolution pick up sensor assembly.
CONTROL VALVE CHECKThe control valve detects a low pressure level during the
operation of the air conditioner, and adjusts the amount of
refrigerant to be bypassed.
(1) Operate the air conditioner under a high temperature loadcondition (when vehicle interior temperature is high).
(2) Connect a low pressure gauge to the air compressor.
(3) Operate the air conditioner with the engine running at idle.
(4) Gradually increase the engine speed while observing the
low pressure gauge.
If the valve is normal, the low pressure drops slowly as the
engine speed increases until a pressure of 180
kPa (25 psi)
is reached, at which point the pressure temporarily ceasesto drop. Then, the pressure again starts dropping as the
engine speed further increases.If the valve is abnormal, the low pressure drops in direct
proportion to the increase in engine speed without a
temporary leveling off at the 180 kPa (25 psi) pressure level.
If the low pressure drops like this, replace the control valve.
SERVICE POINTS OF REASSEMBLYM556HAF
8. INSTALLATION OF CLUTCH COIL
Align the pin of the clutch coil with the pin hole in the fronthousing, and then fit it into the hole.
7. INSTALLATION OF SNAP RING
Install the snap ring so that the tapered surface is at the
outer side.
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