1991 MITSUBISHI 3000GT check engine

FUEL SYSTEM - Service Adjustment Procedures
(3) Insert a 0.65-mm-thick feeler gauge between the fixed SASand throttle lever.
Terminal @
(sensor output)zensor g&nd)MB991348
1
(4) Loosen the throttle position sensor mounting bolts and turnthe TPS body fully counterclockwise.
(5) In this condition, check that there is continuity across
terminals
@ and @.
(6) Slowly turn the throttle position sensor clockwise until you
find a point at which there is no continuity across terminals
@ and 0. Then, tighten the throttle position sensor
mounting bolt securely.(7) Connect the throttle position sensor connector.
(8) When using the multi-use tester, connect it to the diagnosis
connector.
(9) When not using the multi-use tester, proceed as follows:
@ Disconnect the throttle position sensor connectors andconnect the special tool, Test Harness Set, between
the disconnected connectors.
@ Connect a digital voltmeter between the throttle posi-
tion sensor terminal @ (sensor output) and teminal @
(sensor ground).
(lO)Turn the ignition switch ON (but do not start the engine).
(IlKheck the throttle position sensor output voltage.
When using the multi-use tester, select item No. 14 and
read the throttle position sensor output voltage.
Standard value: 400 - 1,000 mV
(12)lf the voltage is out of specification, check the throttle
position sensor and associated harnesses.
(13)Remove the feeler gauge.
(14)Turn the ignition switch OFF.
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1

13-40FUEL SYSTEM -On-vehicle Inspection of MPI Components
COMPONENTS INSPECTION PROCEDUREM13YBAC
USING MULTI-USE TESTER
(1) Check by the service data and actuator test function. If any ij
abnormality is found, check the body harness, components,
etc. and repair as necessary.
(2) After repair, check again with the multi-use tester to makesure that the input and output signals are now normal.
(3) Erase the self-diagnosis trouble code in memory.
(4) Disconnect the multi-use tester.
(5) Start the engine and perform running test, etc. to make
sure that the troubles have been corrected.
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FUEL SYSTEM - On-vehicle Inspection of MPI Components13-41
POWER SUPPLY AND IGNITION SWITCH-IG
Engine control
unit
16FO29:
Q-i=++=
iA MPI control relay
ml3Yuu
lcmition switch (IG)
@ Harness sideccmnector
62
I
Engine control unit
Engine control unit connector7FUO950
OPERATIONl
While the ignition switch is on, battery power is supplied to the engine control unit, the injector, the airflow sensor, etc.
lWhen the ignition switch is turned on, the battery voltage is applied from the ignition switch to the engine
control unit, which then turns ON the power transistor to energize the control relay coil. This turns ON thecontrol relay switch and the power is supplied from the battery to the engine control unit through the
control relay switch.
INSPECTION
Using Multi-use Tester
IFunctionItem No.Data displayICheck conditionIStandard valueI
Data reading16Engine control unit
power voltageIgnition switch: ONsv
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IS-42FUEL SYSTEM - On-vehicle Inspection of MPI Components
HARNESS INSPECTION
Measure the ignition switch terminalinput voltage.l
Engine control unit connector:
Disconnectedl Ignition switch: ON
01
orOlLO427Voltage
(V)svRepair the
harness.
(Ignitionswitch -@I
Measure the power supply voltage ofthe control relay.l Connector: Disconnected
Voltage
(V)sv
Repair the
harness.
(Battery -
@IIN
ontrolrelay connector: Discon-
Engine controlunit harnessCheck for an open-circuit, or a short-
side connectorcircuit to ground between the enginecontrol unit and the control relay.l
Control relay connector: Discon-l
Engine control unit connector:
Disconnected
1 TSB RevisionI

13-44FUEL SYSTEM - On-vehicle Inspection of MPI Components
ENGINE CONTROL UNIT POWER GROUNDMlBYD~
wEngine controld/ unii16FO292
Engine control unit
L-7-l d
1326
Yx
01A01@1
Engine control unit connector
7FUO653
OPERATIONGrounds the engine control unit
TROUBLESHOOTING HINTSIf the ground wire of the engine control unit is not connected securely to ground, the unit will not operate
correctly.
HARNESS INSPECTION
unit harness
side connector
Check for continuity of the ground
circuit.l
Engine control unit connector:DisconnectedTSB Revision

13-46FUEL SYSTEM - On-vehicle Inspection of MPI Components
INSPECTIONUsing Multi-use Tester
FunctionItem No.DriveCheck condition
Check contentNormal statedActuator test 07
Fuel pump isl Engine cranking
Hold return hose withPulsation is felt
driven to cir-l Forced drive of fuelculate fuelfingers to feel pulsation
pump
Check is made forindicating fuel flow
above two conditions
Listen to pump operating
sound near fuel tankOperating sound isheard
HARNESS INSPECTION
check terminal
7FUO954
@ Harness side
connector7FUO955
Check the fuel pump.l
Apply battery voltage to thechecking terminal and operate the
w-w
Check for continuity of the ground
circuit.l
Fuel pump connector: Discon-
nected
Repair the
harness.
@FJ-Ground)
Check for continuity between the fuelpump and the checking terminal.l
Fuel pump connector: Discon-
nectedcl4
Repair the
harness.
@vJ-@g)
1 TSB Revision

FUEL SYSTEM - On-vehicle inspection of MPI Components
@ Harness side
connector6
1
@ Harness side
connector
77FUO475
-
Engine controlunit harnessside connector
Q Harness side
-1
=7FUO476
9 Harnessside
connec-
tor
@ Harness side connector
7FUO956
Measure th& power supply voltage of
the control relay.l Connector: Disconnected
OK
lIgnition switch: START (when0
@@checked)lIgnition switch: ON (when @@
checked)
cl6
t
Repair the
harness.
(Ignition
switch-[IGI
- @El)
(Ignition
switch-[ST]
- @El)
Check for an open-circuit, or a short-
circuit to ground between the controlrelay and the engine control unit.
lControl relay connector: Discon-nectedl Enaine control unit connector:
Disconnected
Repair the
harness.
@El-lg
Check for continuity of the ground
circuit.l Connector: Disconnected
Repair the
harness.
L%n~)
Check for an open-circuit, or a short-circuit to ground between the controlrelay and the fuel pump.A
lControl relay connector: Discon-nected(OK)+ Adl Fuel pump connector:
Discon-netted
Repair the
harness.
@I@-@g)
I
vision

FUEL SYSTEM - On-vehicle Inspection of MPI Components
13-49 i
Ignition switch [IG]
Ignition switch [ST]
@ Equipment side
connector9 3Control reta)
;i.
L Ll
@ Harness side
connector
Enaine control unitEquipment side
connector
M-ii
Resistorw(for fuel pump)
Equipment side
connector
II &A
8 A21
@ Equipment
side@I Harness side
connector
connector
M
‘r
Y
2
7
Y
Fuelpump
-JFuel pumpcheck terminal
7FUO959Engine control unit connector
7FUO653
idTSB Revision