1991 MITSUBISHI 3000GT display

FUEL SYSTEM - On-vehicle Inspection of MPI Components
L
L
IGNITION SWITCH-ST
lgnitlon switch (ST)
I
Enaine control unit connector
7FUO653
Engine control unit
1 FU0638
OPERATION
lThe ignition switch-ST inputs a high signal to the engine control unit while the engine is cranking. Theengine control unit provides fuel injection control, etc., at engine startup based on this signal.
lWhen the ignition switch is set to START, the battery voltage at cranking is applied through the ignitionswitch to the engine control unit, which detects that the engine is cranking.
INSPECTION
Using Multi-use Tester
FunctionItem No. Data displayCheck conditionEngineNormal indication
Data reading18Switch stateIgnition switch: ONstopOFF
CrankingON
HARNESS INSPECTION
1
L6FU1258
2
1
Engine control
side connector
IY-6FU1259
Measure the input voltage to theengine control unit.nlEngine control unit connector:Disconnectedl Ignition switch: START
Check for continuity of the groundcircuit.
lEngine control unit connector:Disconnected
Repair the
harness.
(m - Ground)
iTSB Revision

FUEL SYSTEM - On-vehicle Inspection of MPI Components13-77INSPECTION
Using Multi-use Tester
LIGNITION SWITCH-ST
FunctionItem No. Data displayCheck conditionEngineNormal rndrcation
Data reading18Switch stateIgnition switch: ON
stopOFF
CrankingONINHIBITOR SWITCH
FunctionItem No. Data displayCheck conditionSelect lever positionNormal indicationData reading 29
Shift
Ignition switch: ONP or NP or Nposition
D.2,L or RD.2.L or RHARNESS INSPECTION
@ Harness sideconnector
OlA0206
2
@ Harness srdeconnectorl
Engine control unit connector:
Connectedl
InhibItor switch connector: Dis-6a
L-J
cl3
connectedl Ignition switch: ON
Repair the
harness.Voltage
(VI@El - El)
OlA0206LII
Engine control
unit harness
side connector
Measure the power supply voltage of
the inhibitor switch.
-lEngine control unit connector:
Disconnectedl
lnhibrtor switch connector: Dis-
connectedl Ignition switch: START
Voltage
(V)
rLlltXK IlIt:Lpower supplycircuit.
Measure the inhibitor switch terminalinput voltage.
Measure the input voltage of enginecontrol unit.lEngine control unrt connector:DisconnectedlFer;it;r switch connector: Con-
1 TSB Revision

FUEL SYSTEM- On-vehicle Inspection of MPI Components13-81
INSPECTIONUsing Multi-use Tester
Function
Data readingItem No. Data displayCheck conditionSteering wheelNormal indication
27Switch stateEngine: IdlingSteering wheel neutralOFFposition (wheels
straight-ahead direction)
Steering wheel half turn
ON
Checking Oil Pressure
Steering wheelOil pump delivery pressure (ref. value)
Straight forward700 - 1,200 kPa (100 - 171 psi)
Turned1,500
- 2,000 kPa (213 - 284 psi)
HARNESS INSPECTION
i1
@ Harness side
connector
Measure the power supply voltage.
SENSOR INSPECTIONRefer to GROUP 37
- Service Adjustment Procedures.
TSB Revision

13-82FUEL SYSTEM - On-vehicle Inspection of MPI Components
AIR CONDITIONER SWITCH AND POWER RELAY
\
*I \\-- \
Air conditronerAir conditioner
control unitAir conditioner
compressor lock
controllerr
Engine control unit
Dual pressureswitch
M13YRAA2
b1IFF
Air conditioner
compressor
Engine control
unit connector
7FUO966
7FUO653
OPERATION
lThe air conditioner switch applies the battery voltage to the engine control unit when the air conditioner is
turned on.
lWhen the air conditioner ON signal is input, the engine control unit drives the idle speed control servo and
turns ON the power transistor. As a result, the air conditioner power relay coil is energized to turn on therelay switch, which activates the air compressor magnetic clutch.
TROUBLESHOOTING HINTS
If the air compressor magnet clutch is not activated when the air conditioner switch is turned on during idling,faulty air conditioner control system is suspected.
INSPECTION
Using Multi-use Tester
AIR CONDITIONER SWITCH
Function1 Item No. 1 Data display 1Check condition) Air conditioner switch 1 Normal indication IData reading 28
Switch stateEngine: Idling (airOFFOFFcompressor to be running
when air conditionerONONswitch is ON)\k”JTSB Revision

FUEL SYSTEM - On-vehicle Inspection of MPI Components
AIR CONDITIONER POWER RELAY
L
FunctionItem No. Data display
Data reading49Air condi-tioner relay
stateCheck conditionEngine: Idling after
warm-up
HARNESS INSPECTIONAir conditioner switch
Normal indication
OFFOFF (compressor
clutch non-activa-
tion)
ONON (compressorclutch activation)
’ I
unit harness
side connector
7FUO695
Measure the power supply voltage of
the air conditioner circuit.l
Air conditioner switch: ONlEngine control unit connector:
Disconnectedl Ignition switch: ON
l
Dual air conditioner switch: ONVoltage
(V)IM
ASTOP
Check the airconditioner
circuit.
AIR CONDITIONER INSPECTIONRefer to GROUP 55
- Service Adjustment Procedures.
TSB Revision

13-86FUEL SYSTEM - On-vehicle Inspection of MPI Components
ELECTRICAL LOAD SWITCH16FO29;
Tail-lightrelayDefog.wrelaystoplight
t;1
switch
ti* . .
Engine control unit connector
Engine
control
unit7FUO653
7FUO688OPERATION
lThe electrical load switch inputs ON/OFF state of the switch of equipment that consumes much powerduring idling, namely, equipment with a large electrical load, to the engine control unit. Based on this
signal, the engine control unit controls the idle-speed control servo.
l
When the switch of equipment with a large electrical load is turned ON, the battery voltage is applied tothe engine control unit to indicate that the equipment switch is turned ON.,
LJINSPECTION
Using Multi-use Tester
Function
Data reading
I
tem No. Data display
-I-
33Switchstate
Check condition
Equipment stateNormal display
$;ration of equipment:L$ing;Atch only:OFF + ON-3
1 TSB Revision

13-88FUEL SYSTEM - On-vehicle Inspection of MPI Components
MUFFLER MODE CHANGEOVER SWITCH
Engine control unit
r
@ Equipment sideconnector3
-Muffler
modeOFF changeover
ONswitch
2
r
7FU1053
OPERATIONlIf the operator turns the muffler mode changeover switch to ON or OFF position, this is converted to
high/low voltage to be sent to the engine control unit. Receiving this signal, the engine control unit
performs the dual mode (TOUR/SPORT mode) muffler control.
lThe output terminal of the muffler mode changeover switch has battery voltage applied to it from the
engine control unit through the resistor inside the unit. Place the muffler-mode changeover switch to the ‘LJj
ON posrtton, and the muffler mode changeover switch circuit will be closed to short the voltage applied
output terminal to the ground.. Accordingly, the output voltage of the muffler mode changeover switchchanges from high to low.
INSPECTION
Using Multi-use Tester
FunctionItem No. Data displayCheck conditionMuffler mode changeover Normal displayswitch condition
Data list35Switch
conditionIgnition switch: ONTurn to TOUR mode
Turn to SPORT modeON
OFFTSB Revision

FUEL SYSTEM- On-vehicle Inspection of MPI Components13-93INSPECTION
Using Multi-Use Tester
FunctionItem No. Data displayCheck conditionEngine stateStandard valueData reading 43
SensorEngine: Warmed up700 rpm (Idle)100°C (212°F) or less
temperatureEngine is maintained in-
a constant state for3,500 rpm120°C (248°F) or more
2 minutes or moreHARNESS INSPECTION
connector
2-..-I
@ Harness side
connector
m2 1
4
1
Measure the power supply voltage.l Connector: Disconnected
l Ignition switch: ON
Voltage
(V)4.3
- 4.7Repair the
harness.
(@I@ - q I
Check for continuity of the groundcircuit.
l Connector: Disconnected
I
Repair the
harness.@@J-m,
SENSOR INSPECTION
Refer to GROUP 17 - Exhaust Gas Recirculation (EGR) System.TSB Revision