MITSUBISHI MONTERO 1991 Service Manual

throttle body to prevent solvent from entering passage.
4) Clean throttle body with solvent. Replace air intake hose.
Recheck basic idle speed. If basic idle speed is within specification
after cleaning throttle body, go to step 9). If basic idle speed is
still not within specification after cleaning throttle body,
disconnect jumper wires connected in steps 1) and 2). On all models
except Eclipse, Galant and Mirage, go to step 6). On Eclipse, Galant
and Mirage, go to step 5).
5) Adjust idle position switch and go to step 7). See IDLE
POSITION SWITCH under THROTTLE POSITION SENSOR (TPS).
6) Adjust fixed Speed Adjusting Screw (SAS) and go to next
step. See FIXED SPEED ADJUSTING SCREW under IDLE SPEED & MIXTURE.
7) Reconnect jumper wires as indicated in steps 1) and 2).
Check basic idle speed. If basic idle speed is within specification,
go to step 9). If basic idle speed is not within specification, adjust
by turning idle speed adjusting screw on throttle body. See Fig. 2. Go
to next step.
8) If basic idle speed is within specification after turning
idle speed adjusting screw, go to step 9). If basic idle speed cannot
be adjusted to specification by turning idle speed adjusting screw,
check for leaking fast idle air valve. Replace throttle body if fast
idle air valve leaks.
9) Turn ignition off. Disconnect jumper wires from ignition
timing adjustment connector and diagnostic connector. Operate engine
at idle for about 5 minutes. Ensure engine idles smoothly and within
curb idle specification. See IDLE SPEED SPECIFICATIONS table.
IDLE SPEED SPECIFICATIONS TABLE









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Application Curb Idle Basic Idle
1.5L
Colt, Colt 200,
Mirage & Summit .... 650-850 ...... 700-800
1.6L
Mirage .............. 650-850 ...... 700-800
1.8L
Eclipse ............. 600-800 ...... 650-750
2.0L (VIN V)
Colt Vista .......... 600-800 ...... 650-750
Galant .............. 650-850 ...... 700-800
2.0L (VIN R & U)
Eclipse ............. 650-850 ...... 650-750
Galant .............. 650-850 ...... 700-800
2.4L
Pickup & Ram-50 ..... 650-850 ...... 700-800
3.0L
Montero, Pickup, Ram-50,
Stealth & 3000GT . 600-800 ...... 650-750









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Fig. 1: Idle & Fixed Speed Adj. Screws (1.5L, 1.8L, 2.0L (VIN V)
& 2.4L)

Courtesy of Mitsubishi Motor Sales of America.
Fig. 2: Idle Speed Adj. Screw (1.6L, 2.0L (VIN R & U) & 3.0L)
Courtesy of Mitsubishi Motor Sales of America.
Fig. 3: Identifying Diagnostic Connector Terminal
Courtesy of Mitsubishi Motor Sales of America.
FIXED SPEED ADJUSTING SCREW

NOTE: Fixed Speed Adjusting Screw (SAS) is preset by manufacturer
and usually does not require adjustment. Only adjust fixed
SAS if other adjustment procedures require it, or if
manufacturer's original setting has been changed.
3.0L Montero, Pickup, Ram-50, Stealth & 3000GT
1) Loosen throttle cable. Loosen fixed SAS lock nut. See
Fig. 4. Turn fixed SAS counterclockwise until throttle valve is fully
closed. Turn fixed SAS clockwise until throttle valve begins to open.
Turn fixed SAS clockwise 1 1/4 turns after throttle valve begins to
open.
2) Tighten lock nut while holding fixed SAS in position.
Adjust throttle cable. Adjust basic idle speed. See BASIC IDLE SPEED
under IDLE SPEED & MIXTURE. Adjust throttle position sensor. See
THROTTLE POSITION SENSOR (TPS).
All Other Models
To adjust fixed SAS, adjust basic idle speed. See BASIC IDLE
SPEED under IDLE SPEED & MIXTURE.
Fig. 4: Fixed Speed Adj. Screw & Feeler Gauge Pos. (3.0L)
Courtesy of Mitsubishi Motor Sales of America.
IDLE MIXTURE

NOTE: Idle mixture is computer controlled on fuel injected engines
and is nonadjustable. CO level specifications are not
available from manufacturer.
THROTTLE POSITION SENSOR (TPS)
TPS ADJUSTMENT
NOTE: Ensure basic idle speed is set to specification before
adjusting TPS. See BASIC IDLE SPEED under IDLE SPEED &
MIXTURE. Perform all adjustments with engine at normal
operating temperature, front wheels in straight-ahead
position, cooling fan and all accessories off, and
transmission in Park or Neutral.
TPS TEST APPLICATION









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Application Test
1.5L
Colt, Colt 200,
Mirage & Summit ............. TEST NO. 1
1.6L
Mirage ....................... TEST NO. 2
1.8L
Eclipse ...................... TEST NO. 3
2.0L (VIN V)
Colt Vista & Galant .......... TEST NO. 1
2.0L (VIN R & U)
Galant ....................... TEST NO. 1
Eclipse ...................... TEST NO. 3
2.4L
Pickup & Ram-50 .............. TEST NO. 1
3.0L
Montero, Pickup & Ram-50 ..... TEST NO. 4
Stealth & 3000GT ............. TEST NO. 5









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Test No. 1
1) Turn ignition on for more than 15 seconds. DO NOT start
engine. Turn ignition off. ISC plunger should be retracted fully.
2) Ensure ISC plunger is in fully retracted position.
Disconnect harness connector(s) from ISC motor. Turn ignition on. DO
NOT start engine.
3) Using digital voltmeter, backprobe terminal No. 19
(Green/White wire) and terminal No. 24 (Black or Green/Black wire) a\
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Engine Control Unit (ECU) wiring harness connector. Note TPS output
voltage.
4) If output voltage is .48-.52 volt, go to step 6). If
output voltage is not .48-.52 volt, loosen TPS mounting screw(s) and
rotate TPS clockwise, or counterclockwise, until output voltage is
within specification. Tighten TPS mounting screws.
5) Turn ignition off. Reconnect harness connector(s) at ISC
motor. Start engine. Ensure engine idles within curb idle speed
specification.
6) Turn ignition off. Disconnect negative battery cable for
at least 15 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. 2
1) Turn ignition on. DO NOT start engine. Loosen throttle

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

Adjusting Screw (SAS) and throttle lever. See Fig. 4. Loosen TPS
mounting screws. Rotate TPS fully counterclockwise. Check for
continuity between Yellow/Red wire and Black wire terminals of TPS.
3) Rotate TPS clockwise until ohmmeter registers no
continuity. Tighten TPS mounting screws. Reconnect TPS electrical
connector.
4) Use a digital voltmeter to backprobe terminal No. 19
(Brown/Red wire) and terminal No. 24 (Brown wire) at Engine Control
Unit (ECU) wiring harness on SOHC vehicles, or terminal No. 64
(Brown/Red wire) and terminal No. 72 (Black wire) on DOHC vehicles.
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 step 6).
6) Remove feeler gauge. Turn ignition off. Disconnect
voltmeter from ECU connector. Operate engine at idle for about 5
minutes to ensure engine idles smoothly and within specification.
IDLE POSITION SWITCH
NOTE: Idle position switch is preset by manufacturer. Adjustment
is usually not necessary. If other procedures in this
article require adjustment of idle position switch or if
switch setting has been changed, adjust switch as follows.
1.6L Mirage, 2.0L Eclipse & 2.0L Galant (DOHC)
1) Loosen throttle cable. Disconnect electrical connector
from idle position switch. See Fig. 5. Loosen lock nut at base of
switch. Turn switch counterclockwise until throttle valve is fully
closed.
2) Connect ohmmeter between switch terminal and switch body
(ground). Turn idle position switch clockwise until ohmmeter registers\
continuity. At this point, throttle valve should begin to open.
3) Turn switch 15/16 of a turn beyond contact point. Tighten
lock nut at base of idle position switch, holding switch to prevent it
from turning while tightening.
4) Adjust throttle cable. Adjust basic idle speed. See BASIC
IDLE SPEED. Adjust TPS. See TPS ADJUSTMENT.
All Other Models
Idle position switch is incorporated in ISC motor and is
automatically adjusted when TPS is adjusted. See TPS ADJUSTMENT.
Fig. 5: Idle Position Switch Location (1.6L & 2.0L (VIN R &U))
Courtesy of Mitsubishi Motor Sales of America.

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.

Fig. 2: Charging System Wiring Schematic (Colt Vista)
Courtesy of Chrysler Motors.

Fig. 3: Charging System Wiring Schematic (Eclipse)
Courtesy of Mitsubishi Motor Sales of America.

Fig. 4: Charging System Wiring Schematic (Galant)
Courtesy of Mitsubishi Motor Sales of America.