1991 MITSUBISHI MONTERO battery

cable. Using digital voltmeter, backprobe terminal No. 19 (Green/White
wire) and terminal No. 24 (Black or Green/Black wire) at Engine
Control Unit (ECU) wiring harness connector. Check TPS output voltage.\
2) If output voltage is .48-.52 volt, go to step 3). If
output voltage is not .48-.52 volt, remove throttle body. Loosen TPS
mounting screws and rotate TPS clockwise, or counterclockwise, until
output voltage is within specification. Tighten TPS mounting screws.
3) Turn ignition off. Disconnect voltmeter from ECU harness
connector. Adjust throttle cable. Disconnect negative battery cable
for at least 10 seconds to clear diagnostic code. Reconnect negative
battery cable. Operate engine at idle for about 5 minutes to ensure
engine idles smoothly.
Test No. 3
1) Turn ignition on for more than 15 seconds. DO NOT start
engine. Turn ignition off. This should fully retract ISC plunger.
2) Ensure ISC plunger is fully retracted. Disconnect TPS
harness connectors. Connect Test Harness (MD998474) between
connectors. Connect digital voltmeter between Red and Blue wires of
test harness.
3) Turn ignition on. DO NOT start engine. TPS voltage should
be .48-.52 volt. If TPS voltage is .48-.52 volt, go to step 4). If TPS
voltage is not .48-.52 volt, loosen TPS mounting screws and rotate TPS
clockwise, or counterclockwise, until correct voltage is obtained.
Tighten TPS mounting screws.
4) Turn ignition off. Disconnect voltmeter and remove test
harness. Reconnect TPS harness connectors. Adjust throttle cable.
Start engine and check idle speed.
5) Turn ignition off. Disconnect negative battery cable for
at least 10 seconds to clear diagnostic trouble code. Reconnect
negative battery cable. Operate engine at idle for about 5 minutes to
ensure engine idles smoothly.
Test No. 4
1) Loosen throttle cable. Disconnect electrical connector
from TPS. Connect digital ohmmeter between Green/White and
Green/Yellow wire terminals of TPS electrical connector (on TPS side
of harness).
2) Insert .026" (.66 mm) feeler gauge between fixed Speed
Adjusting Screw (SAS) and throttle lever. See Fig. 4. Loosen TPS
mounting screws. Rotate TPS fully clockwise. Check for continuity
between Green/White wire and Green/Yellow wire terminals of TPS
electrical connector.
3) Rotate TPS counterclockwise until ohmmeter registers no
continuity. Tighten TPS mounting screws and reconnect TPS electrical
connector.
4) Using digital voltmeter, backprobe terminal No. 19
(Green/White wire) and terminal No. 24 (Black or Green/Black wire) a\
t
Engine Control Unit (ECU) wiring harness connector. Turn ignition on.
DO NOT start engine. Check TPS output voltage.
5) If TPS output voltage is 0.4-1.0 volt, go to step 6). If
TPS output voltage is not 0.4-1.0 volt, check TPS and wiring harness
for damage or malfunction. Replace TPS or repair wiring harness if
necessary and go to next step.
6) Remove feeler gauge. Turn ignition off. Disconnect
voltmeter from ECU connector. Adjust throttle cable. Operate engine at
idle for about 5 minutes to ensure engine idles smoothly and within
specification.
Test No. 5
1) Disconnect electrical connector from TPS. Connect digital
ohmmeter between Yellow/Red wire and Black wire terminals of TPS.
2) Insert .026" (.66 mm) feeler gauge between fixed Speed

ALTE R NATO R & R EG ULA TO R

1991 M it s u bis h i M onte ro
1991 ELECTRICAL
Alternators & Regulators
Colt, Colt Vista, Colt 200, Ram-50, Stealth, Summit;
Eclipse, Galant, Mirage, Montero, Pickup, Precis, 3000GT
DESCRIPTION
Mitsubishi alternators are conventional 3-phase, self-
rectifying type units containing 6 diodes (3 positive and 3 negative)
which are used to rectify current. All models use a case-mounted
Integrated Circuit (IC) voltage regulator.
Alternator relay or resistor with diode is used to ensure
charging of battery even if charging indicator light is defective. See
Figs. 1 -9.
Fig. 1: Charging System Wiring Schematic (Colt, Mirage & Summit)
Courtesy of Mitsubishi Motor Sales of America.

BELT ADJUSTMENT TABLE








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Application ( 1) New Belt Deflection: In. (mm)
Colt, Colt 200 & Summit ..................... .28-.35 (7.1-8.9)
Mirage
1.5L ...................................... .28-.35 (7.1-8.9)
1.6L ..................................... .35-.45 (8.9-11.4)
Colt Vista .................................. .28-.34 (7.1-8.6)
Eclipse & Galant
1.8L ..................................... .32-.43 (8.1-10.9)
2.0L ..................................... .35-.45 (8.9-11.4)
Montero ..................................... .22-.32 (5.6-8.1)
Pickup & Ram-50
2.4L ...................................... .28-.39 (7.1-9.9)
3.0L ...................................... .32-.39 (8.1-9.9)
Precis ...................................... .28-.32 (7.1-8.1)
Stealth & 3000GT
DOHC ...................................... .16-.22 (4.1-5.6)
SOHC ...................................... .24-.35 (6.1-8.9)
( 1) - Deflection measured with 22 lbs. (10 kg) pressure applied midway
on belt run.









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TROUBLE SHOOTING
NOTE: See TROUBLE SHOOTING - BASIC PROCEDURES article in the
GENERAL INFORMATION section.
TESTING (ON-VEHICLE)
ALTERNATOR TO BATTERY CONTINUITY TEST
NOTE: Check alternator wire harness connections and drive belt
tension and ensure battery is fully charged before
performing test.
1) Turn ignition switch to OFF position. Disconnect negative
battery cable. Remove output lead from alternator terminal "B". See
Fig. 10 . Install a 100-amp ammeter in series to terminal "B" and
disconnected output lead. Install positive lead of ammeter to terminal
"B" and negative lead to disconnected output wire.
Fig. 10: Identifying Alternator Terminals
Courtesy of Chrysler Motors.
2) Install a digital voltmeter between alternator terminal
"B" and positive battery terminal. Install positive voltmeter lead to

terminal "B" and negative lead to positive battery terminal. Reconnect
negative battery cable.
3) Start engine. Turn accessories on and adjust engine speed
until ammeter indicates 20 amps, and note voltmeter reading. If
voltmeter indicates .2 volt or less, system is okay.
4) If voltage is greater than .2 volt, wiring is defective
between alternator terminal "B", fusible link and battery positive
terminal. Disconnect negative battery cable, and remove test
equipment.
ALTERNATOR OUTPUT TEST
NOTE: During alternator output test, a slightly discharged battery
should be used as a fully charged battery may not allow full
alternator output.
1) Turn ignition switch to OFF position. Disconnect negative
battery cable. Disconnect alternator output wire from terminal "B".
Install positive lead of 100-amp ammeter to terminal "B" and negative
lead to disconnected output lead.
CAUTION: Tighten each connection securely as heavy current flow will
exist. DO NOT use clips on ammeter.
2) Connect positive voltmeter lead (0-20 volts) to alternato\
r
terminal "B" and negative lead to ground. Install tachometer, and
reconnect negative battery cable.
3) Ensure voltmeter indicates battery voltage. If no voltage
exists, an open circuit is present in wire between alternator terminal
"B" and battery negative terminal. Check grounds and fusible link.
4) Turn headlights on, and start engine. Set headlights at
high beam and heater switch on HIGH. Quickly accelerate engine speed
to 2500 RPM and note alternator output current registered on the
ammeter. Minimum output should be within specification. Refer to the
ALTERNATOR MINIMUM OUTPUT SPECIFICATIONS table.
NOTE: Output voltage changes with electrical load and temperature.
Ensure proper electrical load is applied while checking
output. Nominal output may not be obtained if alternator or
ambient temperature is excessive. Allow to cool, and recheck
output. Alternator output is stamped on metal plate attached
to alternator case.
5) If minimum output is not obtained and alternator wiring is
okay, repair alternator. Disconnect negative battery cable, and remove
test equipment.
REGULATED VOLTAGE TEST
NOTE: Ensure battery is fully charged and proper drive belt
tension exists.
1) Turn ignition switch to OFF position. Disconnect negative
battery cable. Install a digital voltmeter between alternator terminal
"S" and ground. See Fig. 10. Connect positive voltmeter lead to
terminal "S" of alternator. Connect negative voltmeter lead to ground.
2) Disconnect alternator output wire from terminal "B".
Install a 100-amp ammeter in series to terminal "B" and disconnected
output lead. Install positive lead of ammeter to terminal "B" and
negative lead to disconnected output wire. Install a tachometer, and
reconnect negative battery cable.
3) Turn ignition switch to ON position and ensure voltmeter
indicates battery voltage. If no voltage exists, an open circuit

exists in wire between alternator terminal "S" and positive battery
terminal or fusible link is blown.
4) Start engine. Ensure all lights and accessories are off.
Operate engine at 2500 RPM and read voltmeter when alternator output
current drops to 10 amps or less. Voltage regulator is okay if voltage
output is within specification. See REGULATOR VOLTAGE SPECIFICATIONS
table.
BENCH TESTING
RECTIFIER ASSEMBLY
1) Using ohmmeter, check for continuity between both diodes
and stator coil lead connection. See Fig. 11. Reverse leads. If
continuity exists in both directions, diode is shorted. Replace
rectifier assembly.
2) To check entire diode assembly, use an ohmmeter to check
for continuity between both ends of each diode. See Fig. 11. Switch
ohmmeter leads. Continuity should exist in one direction, but not
other. If no continuity exists or continuity exists in both
directions, diode is defective. Replace rectifier assembly.
Fig. 11: Testing Rectifier Assembly
Courtesy of Mitsubishi Motor Sales of America.
ROTOR

2.0L (VIN R) DOHC ......................... 137 (9.6)
2.0L (VIN U) DOHC Turbo ................... 114 (8.0)
2.0L (VIN V) SOHC ......................... 119 (8.4)
2.4L (VIN W) SOHC ......................... 119 (8.4)
3.0L (VIN S) SOHC ......................... 119 (8.4)
3.0L (VIN B) DOHC ......................... 139 (9.8)
3.0L (VIN C) DOHC Turbo ................... 115 (8.1)
(1) - Maximum variation between cylinders 14 psi
(1.0 kg/cm
)








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Exhaust System Backpressure
Exhaust system can be checked with a vacuum or pressure
gauge. Remove O2 sensor or air injection check valve (if equipped).
Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If
exhaust system backpressure is greater than 1 3/4-2 psi, exhaust
system or catalytic converter is plugged. If a vacuum gauge is used,
connect vacuum gauge hose to intake manifold vacuum port and start
engine. Observe vacuum gauge. Open throttle part way and hold steady.
If vacuum gauge reading slowly drops after stabilizing, exhaust system
should be checked for a restriction.
FUEL PRESSURE
Basic diagnosis of fuel system should begin with determining
fuel system pressure.
FUEL INJECTED ENGINES
WARNING: ALWAYS relieve fuel pressure before disconnecting any fuel
injection-related component. DO NOT allow fuel to contact
engine or electrical components.
Fuel Pressure
1) On all models except Colt and Mirage, disconnect fuel pump
harness connector at fuel tank. On Colt and Mirage, remove rear seat
cushion to disconnect fuel pump harness connector.
2) On all models, start engine. Let engine run until it
stops. Turn ignition off. Disconnect negative battery terminal.
Connect fuel pump harness connector.
WARNING: Before disconnecting high pressure fuel hose at fuel delivery
pipe, cover fuel hose connection with a rag. Some residual
fuel pressure may still be in system.
3) On Galant 2.0L (DOHC), remove brace for access to high
pressure fuel delivery pipe. On all engines, disconnect high pressure
fuel hose at fuel delivery pipe.
4) Connect fuel pressure gauge with adapter between fuel
delivery pipe and high pressure hose. See Fig. 1. Connect negative
battery terminal. Connect battery voltage to fuel pump test terminal.
See FUEL PUMP TEST TERMINAL LOCATION table. Ensure no fuel leaks are
present. Disconnect battery voltage to fuel pump test terminal.

pump. If fuel pressure drops slowly, fuel injector is leaking or fuel
pressure regulator valve seat is leaking. Check for faulty fuel
injector or fuel pressure regulator. Repair as required.
11) When fuel pressure test is complete, repeat fuel pressure
release procedure in steps 1) and 2) before disconnecting fuel
pressure gauge. Install new "O" ring at end of high pressure hose.
Check for fuel leaks.
FUEL PUMP TEST TERMINAL LOCATION TABLE









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Application Wire Color Location
Colt, Colt 200 ......... BLK/WHT .............. Center Of Firewall
Colt Vista ............. BLK/WHT ........ Right Center Of Firewall
Eclipse ................ BLK/WHT .......... Rear Of Battery Compt.
Galant ................. YEL/GRN ........... Left Rear Eng. Compt.
Mirage 1.5L ............ BLK/WHT .............. Center Of Firewall
Mirage 1.6L ............ BLK/BLU .............. Center Of Firewall
Montero .................. WHT .......... Right Center Of Firewall
Pickup ................. BLK/BLU ....... Right Side Of Eng. Compt.
Precis ................... YEL ............. Left Rear Eng. Compt.
Summit ................. BLK/WHT .............. Center Of Firewall
Ram-50 ................. BLK/BLU ....... Right Side Of Eng. Compt.
Stealth, 3000GT ........ BLK/BLU .......... Rear Of Battery Compt.









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REGULATED FUEL PRESSURE TABLE








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At Idle At Idle
w/Vacuum w/o Vacuum
Application psi (kg/cm
) psi (kg/cm)
Non-Turbo .................. 38 (2.7) ....... 47-50 (3.3-3.5)
Turbo
Except Eclipse A/T ....... 27 (1.9) ....... 36-38 (2.5-2.7)
Eclipse A/T .............. 33 (2.3) ....... 36-38 (2.9-3.2)









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Control Relay
Multipurpose relay switches power to vehicle sensors and
actuators including airflow sensor, crank angle sensor, idle speed
control, injectors and fuel pump. When ignition switch is turned to ON
position, ECU energizes coils controlling injectors, airflow sensor
and idle speed control. When ignition switch is turned to START
position, ECU energizes coils (through inhibitor switch on A/T models)\
to supply power to fuel pump. Relay failure will cause a no-start
condition. For testing procedure, see SYSTEM & COMPONENT TESTING
article.
IGNITION CHECKS
SPARK
Check for spark at coil wire (if applicable) and at each
spark plug wire using a high output spark tester. Check spark plug
wire resistance on suspect wires. For wire resistance specification,
see C - SPECIFICATIONS article in the ENGINE PERFORMANCE Section.
CRANK ANGLE SENSOR
For crank angle sensor testing procedure on all models except
Ram-50, Stealth, Eclipse, Laser, Pickup and 3000GT, see TEST NS-5:

Ignition Coil Resistance (Eclipse 2.0L)
1) Using a DVOM, measure primary coil resistance between
ignition coil connector terminals No. 2 and No. 4 (coils for cylinders
No. 1 and No. 4) and between terminals No. 4 and No. 1 (coils for
cylinders No. 2 and No. 3). See Fig. 2.
2) Measure secondary coil resistance between coil towers for
cylinders No. 1 and No. 4 and between coil towers for cylinders No. 2
and No. 3. See Fig. 3. Primary and secondary coil resistance should be
within specification. See DIS IGNITION COIL RESISTANCE table.
DIS IGNITION COIL RESISTANCE TABLE Ohms @ 68
F (20C)








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Application Primary Secondary
All Models ........... .77-.95 .......... 10.3-13.9









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Power Transistor (Eclipse)
1) Disconnect power transistor connector. Using an analog
ohmmeter, connect positive ohmmeter lead to terminal No. 7 and
negative lead to terminal No. 3. See Fig. 4. Ensure there is no
continuity.
Fig. 4: Power Transistor Connector ID (Eclipse)
Courtesy of Mitsubishi Motor Sales of America.
2) Using a 1.5-volt dry cell battery, connect positive end of
1.5-volt battery to power transistor terminal No. 6 and negative end
to terminal No. 3. Ohmmeter should now read continuity between power
transistor terminals No. 7 and No. 3.
3) Connect positive end of 1.5-volt battery to power
transistor terminal No. 2 and negative end to terminal No. 3. Connect
positive ohmmeter lead to terminal No. 1 and negative lead to terminal
No. 3. Ohmmeter should read continuity. Replace power transistor if it
does not test as described.
Power Transistor (Colt Vista, Galant, Montero, Pickup &
Ram-50)
1) Disconnect power transistor connectors. Using a DVOM,
connect positive ohmmeter lead to terminal No. 2 and negative lead to
terminal No. 3. See Fig. 5. Ensure there is no continuity.