automatic transmission MITSUBISHI MONTERO 1991 Owner's Guide

connector portion of sensor slightly above water.
2) Gradually heat water and read resistance values across
terminal connectors. See COOLANT TEMPERATURE SENSOR RESISTANCE table.
If resistance is not within specification, replace sensor.
COOLANT TEMPERATURE SENSOR RESISTANCE TABLE









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TemperatureF (C) Ohms
Montero & Pickup 3.0L
32 (0) ............................. 5900
68 (20) ............................ 2500
104 (40) ........................... 2700
176 (80) ............................ 300
All Others
32 (0) ............................. 5900
68 (20) ............................ 2500
104 (40) ........................... 1100
176 (80) ............................ 300









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CRANK ANGLE SENSOR
See IGNITION SYSTEM.
DETONATION SENSOR
See IGNITION SYSTEM.
EGR TEMPERATURE SENSOR
California
See EXHAUST GAS RECIRCULATION (EGR) under EMISSION SYSTEMS &
SUB-SYSTEMS.
IDLE POSITION SWITCH
NOTE: Idle position switch is incorporated in idle speed control
motor assembly, motor position sensor or throttle position
sensor, depending upon vehicle application.
Pickup 2.4L & Ram-50 2.4L
1) Disconnect motor position sensor (MPS) connector. Connect\
ohmmeter lead between ground and MPS connector terminal No. 4. See
Fig. 2 .
2) With accelerator pedal pressed, no continuity should be
present. With accelerator pedal released, continuity should be
present. If switch continuity is not as specified, replace MPS.
Montero, Pickup 3.0L & Ram-50 3.0L
1) Disconnect throttle position sensor (TPS) connector.
Connect ohmmeter between TPS connector terminals No. 1 and 2. See
Fig. 6 .
2) With accelerator pedal pressed, no continuity should be
present. With accelerator pedal released, continuity should be
present. If idle switch continuity is not as specified, replace TPS.
INHIBITOR SWITCH
Automatic Transmission
Switch is mounted to automatic transaxle, near shift lever

Inhibitor Switch (Automatic Transmission Only)
Inhibitor switch senses position of transmission select
lever, indicating engine load due to automatic transmission
engagement. Based on this signal, ECU commands ISC motor to increase
throttle angle, maintaining optimum idle speed.
Intake Air Temperature Sensor
Incorporated in airflow sensor assembly, this resistor-based
sensor measures temperature of incoming air and supplies air density
information to ECU.
Motor Position Sensor (MPS)
Incorporated in ISC motor (or separate unit on some models),
senses ISC motor plunger position and sends electrical signal to ECU.
Oxygen (O2) Sensor
Located in exhaust system, generates an output voltage.
Output voltage varies with oxygen content of exhaust gas stream. ECU
adjusts air/fuel mixture based on signals from oxygen sensor.
Power Steering Oil Pressure Switch
Detects increase in power steering oil pressure. When power
steering oil pressure increases, switch contacts close, signalling
ECU. ECU commands ISC motor, raising idle speed to compensate for drop
in engine RPM due to power steering load.
TDC Sensor
See CRANKSHAFT ANGLE & TDC SENSOR ASSEMBLY.
Throttle Position Sensor (TPS)
A variable resistor mounted on throttle body. ECU uses
voltage signal received from TPS to determine throttle plate angle.
Vehicle Speed Sensor
Located in speedometer in instrument cluster, uses a reed
switch to sense speedometer gear revolutions. ECU uses gear
revolutions to determine vehicle speed.
OUTPUT SIGNALS
NOTE: Vehicles are equipped with different combinations of
computer-controlled components. Not all components listed
below are used on every vehicle. For theory and operation on
each output component, refer to the system indicated in
brackets after component.
CHECK ENGINE Light
See SELF DIAGNOSTIC SYSTEM.
EGR Control Solenoid Valve
See EXHAUST GAS RECIRCULATION (EGR) CONTROL under EMISSION
SYSTEMS.
Fuel Injectors
See FUEL CONTROL under FUEL SYSTEM.
Fuel Pressure Control Solenoid Valve (Turbo Only)
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pressure Regulator
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pump Relay (MPI Control Relay)

motor to increase idle speed. To prevent A/C compressor from switching
on before idle speed has increased, ECU momentarily opens A/C relay
circuit.
Idle Speed Control (ISC) Motor
Controls pintle-type air valve (DOHC engines) or throttle
plate angle (SOHC engines) to regulate volume of intake air at idle.
During start mode, ECU controls idle intake air volume
according to coolant temperature input. After starting, with idle
position switch activated (throttle closed), fast idle speed is
controlled by ISC motor and fast idle air control valve (if equipped).\
When idle switch is deactivated (throttle open), ISC motor
moves to a preset position in accordance with coolant temperature
input.
When automatic transmission (if equipped) is shifted from
Neutral to Drive, A/C is turned on or power steering pressure reaches
a preset value, ECU signals ISC motor to increase engine RPM.
Fast Idle Air Control Valve
Some models use a coolant temperature-sensitive fast idle air
control valve, located on throttle body, to admit additional intake
air volume during engine warm-up. Control valve closes as temperature
increases, restricting by-pass airflow rate. At engine warm-up, valve
closes completely.
IGNITION SYSTEMS
DIRECT IGNITION SYSTEM (DIS) - DOHC ENGINES
Ignition system is a 2-coil, distributorless ignition system.
Crankshaft angle and TDC sensor assembly, mounted in place of
distributor, are optically controlled.
Power Transistors & Ignition Coils
Based on crankshaft angle and TDC sensor inputs, ECU controls
timing and directly activates each power transistor to fire coils.
Power transistor "A" controls primary current of ignition coil "A" to
fire spark plugs on cylinders No. 1 and 4 at the same time. Power
transistor "B" controls primary current of ignition coil "B" to fire
spark plugs on cylinders No. 2 and 3 at the same time.
Although each coil fires 2 plugs at the same time, ignition
takes place in only one cylinder since the other cylinder is on its
exhaust stroke when plug fires.
ELECTRONIC IGNITION SYSTEM - SOHC ENGINES
Mitsubishi breakerless electronic ignition system uses a disc
and optical sensing unit to trigger power transistor.
Power Transistor & Ignition Coil
Power transistor is mounted inside distributor with disc and
optical sensing unit. When ignition is on, ignition coil primary
circuit is energized. As distributor shaft rotates, disc rotates,
triggering optical sensing unit. ECU receives signals from optical
sensing unit. Signals are converted and sent to power transistor,
interrupting primary current flow and inducing secondary voltage.
IGNITION TIMING CONTROL SYSTEM
Ignition timing is controlled by ECU. ECU adjusts timing
based upon various conditions, such as engine temperature, altitude
and detonation (turbo vehicles only).

TR AN SFE R C ASE

1991 M it s u bis h i M onte ro
1991-94 TRANSFER CASES
Mitsubishi
Dodge; Ram-50
Mitsubishi; Pickup, Montero
APPLICATION
TRANSFER CASE APPLICATIONS TABLE








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Application ( 1) Transmission Model
Dodge
1991-93 Ram-50 (2.4L) .......................... V5M21-1
1991-93 Ram-50 (3.0L M/T) ...................... V5MT1-2
1991-93 Ram-50 (3.0L A/T) ...................... V4AC1-2
Mitsubishi
1991-92 Pickup ................................. V5MT1-2
1991 Montero (M/T) ............................. V5MT1-2
1991 Montero (A/T) ............................. V4AW2-2
1992 Montero (M/T) ......................... ( 2) V5MT1-3
1992 Montero (A/T) ......................... ( 2) V4AW2-3
1993-94 Montero (M/T) ...................... ( 2) V5MT1-2
1993-94 Montero (A/T) ........................ ( 2) R4AC1
( 1) - Transfer case is indicated by a -2 or -3 following the
transmission model number.
( 2) - Transfer cases for Montero are identical for automatic and
manual transmission models.









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DESCRIPTION
Transfer case is a part-time, 2-speed unit with a 3-piece
aluminum case. Transfer case has a floor-mounted shifter and integral
speedometer gear. In Montero a Viscous Coupling Unit (VCU) and center
differential allows 2WD-to-4WD shifting at speeds under 62 MPH and
full-time 4WD operation.
WARNING: When battery is disconnected, vehicles equipped with
computers may lose memory data. When battery power is
restored, driveability problems may exist on some vehicles.
These vehicles may require a relearn procedure. See the
COMPUTER RELEARN PROCEDURES article in the GENERAL
INFORMATION section.
TESTING
4WD INDICATOR CONTROL UNIT (MONTERO)
The 4WD indicator control unit is located behind radio or CD
player. Remove 4WD indicator control unit and disconnect harness.
Backprobe harness connector and measure voltage between terminal No. 8
(ground) and each respective terminal. Compare test results with
chart. See Fig. 1.
DETECTION SWITCH

Disassembly & Reassembly
Remove snap ring, high-low synchronizer hub and low speed
gear. Remove bearing spacer, needle bearing and ball bearing. To
assemble, reverse disassembly procedure. Use thickest snap ring that
will fit into output shaft groove. Acceptable clearance is 0-.003" (0-
.08 mm). See Fig. 4.
INPUT SHAFT ASSEMBLY (RAM-50)
Disassembly & Reassembly
1) Remove snap ring from input shaft. Support bearing in
press. Press input shaft out to remove bearing.
2) On manual transmission models, remove spacer and snap ring
from below bearing. Remove cone spring and sub gear. See Fig. 6. For
reassembly, reverse disassembly procedures.
3) Press bearing into input shaft, pushing against inner
race. After fitting, ensure bearing rotates smoothly. Fit snap ring
over front end of input shaft. Snap rings are available in selective
thicknesses. Select thickest snap ring that will fit in groove.
Fig. 6: Exploded View Of Input Shaft Assembly (Ram-50 - Manual
Shown, Automatic Similar)
Courtesy of Mitsubishi Motor Sales of America.
CENTER DIFFERENTIAL CASE (MONTERO)

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TR AN SM IS SIO N R EM OVA L & IN STA LLA TIO N - A /T
1991 M it s u bis h i M onte ro
199192 TRANSMISSION SERVICING
Transmission Removal & Installation
Mitsubishi: Eclipse, Galant, Mirage, Montero,
Pickup, Precis, 3000GT
MANUAL
NOTE: For manual transmission/transaxle replacement procedures,
see appropriate article in CLUTCHES.
AUTOMATIC FWD MODELS
REMOVAL
1) Remove battery and battery tray. On 3000GT, remove
undercover(s). On Eclipse turbo, drain and remove intercooler. On all
models, remove air cleaner and case. Raise and support vehicle. Remove
wheels. Disconnect control cables at transaxle. Drain transaxle fluid.
2) On Mirage 1.6L, disconnect tension rod. On all models,
disconnect neutral safety switch connector, oil cooler hoses and
electrical connectors from transaxle. Disconnect speedometer cable and
throttle control cable (if equipped). Remove starter motor.
3) On Galant models with electronically controlled
suspension, remove air compressor and bracket. Disconnect front height
sensor rod at lower control arm.
4) On all models, remove upper transaxle-to-engine bolts.
Remove engine undercover (if equipped). On all models, remove drive
axle shafts. See FWD AXLE SHAFTS article in DRIVE AXLES. Separate
lower control arms from struts for access to axle shafts (if
necessary).
5) Remove front exhaust pipe (if necessary). On Eclipse 4WD,\
Galant 4WD and 3000GT, remove right member and gusset. On 4WD models,
separate transfer assembly from transaxle. Reference mark transfer
assembly-to-drive shaft and remove transfer assembly.
6) On all models, remove transmission inspection (dust)
cover. Place index mark on torque converter and drive plate for
reassembly reference. Remove torque converter-to-drive plate bolts.
Push torque converter away from engine into transaxle.
7) Support transaxle with jack. Remove transaxle mounts
bolts, mounting brackets and remaining transaxle-to-engine bolts.
Slide transaxle assembly to right and lower to remove.
CAUTION: Ensure torque converter is fully seated in transaxle before
installation. Always install new snap rings on inner
constant velocity joints.
INSTALLATION
1) To install, reverse removal procedure. Tighten transaxle-
to-engine bolts and torque converter-to-drive plate bolts to
specification. See TORQUE SPECIFICATIONS table at end of article.
2) Ensure reference marks on torque converter-to-drive plate
and transfer assembly-to-drive shaft align. Tighten mounting bolts
with weight of engine and transaxle on mounts. Refill transaxle fluid
to specified level. Adjust all control cables.
RWD MODELS

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TR AN SM IS SIO N S ER VIC IN G - A /T

1991 M it s u bis h i M onte ro
1991 TRANSMISSION SERVICING
Automatic Transmission
Mitsubishi: Eclipse, Galant, Mirage,
Montero, Pickup, Precis, 3000GT
IDENTIFICATION
MITSUBISHI AUTOMATIC TRANSMISSION APPLICATIONS








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Model Transmission/Transaxle
Eclipse
1.8 & 2.0L ........................... Model F4A22 Transaxle
2.0L Turbo ........................... Model F4A33 Transaxle
All-Wheel Drive (AWD) ................ Model W4A33 Transaxle
Galant
AWD .................................. Model W4A32 Transaxle
DOHC ................................. Model F4A22 Transaxle
SOHC ........................ Model KM175 or F4A22 Transaxle
Mirage
1.5L ................................. Model F3A21 Transaxle
1.6L ................................. Model F4A21 Transaxle
Montero ............................ Model V4AW2 Transmission
Pickup ............................. Model R4AC1 Transmission
Precis ................................ Model KM176 Transaxle
3000GT ................................ Model F4A33 Transaxle









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LUBRICATION
TRANSAXLE/TRANSMISSION SERVICE INTERVALS
Check fluid level every 12 months or 15,000 miles. Change
fluid and filter every 30,000 miles. If vehicle is operated under
severe condition, change fluid more often. If severe darkening of
fluid and strong odor are noted, bands should also be adjusted (if
equipped).
TRANSFER CASE SERVICE INTERVALS
On 4WD and AWD models, change transfer case fluid every 30,
000 miles.
CHECKING FLUID LEVEL
TRANSAXLE/TRANSMISSION
1) Park vehicle on level area. Ensure oil is at normal
operating temperature, parking brake is engaged, and engine is at
idle. Move gear selector through each position, stopping briefly in
each position.
2) Place gear selector in Neutral, and clean area around
dipstick tube. Ensure fluid level is between lower and upper marks,
but never over upper mark, in HOT range. Add or drain fluid if
necessary.

In certain conditions, the pitch of the exhaust gases may
sound like gear whine. At other times, it may be mistaken for a wheel
bearing rumble.
Tires, especially radial and snow, can have a high-pitched
tread whine or roar, similar to gear noise. Also, some non-standard
tires with an unusual tread construction may emit a roar or whine.
Defective CV/universal joints may cause clicking noises or
excessive driveline play that can be improperly diagnosed as drive
axle problems.
Trim and moldings also can cause a whistling or whining
noise. Ensure none of these components are causing the noise before
disassembling the drive axle.
Gear Noise
A "howling" or "whining" noise from the ring and pinion gear
can be caused by an improper gear pattern, gear damage, or improper
bearing preload. It can occur at various speeds and driving
conditions, or it can be continuous.
Before disassembling axle to diagnose and correct gear
noise, make sure that tires, exhaust, and vehicle trim have been
checked as possible causes.
Chuckle
This is a particular rattling noise that sounds like a stick
against the spokes of a spinning bicycle wheel. It occurs while
decelerating from 40 MPH and usually can be heard until vehicle comes
to a complete stop. The frequency varies with the speed of the
vehicle.
A chuckle that occurs on the driving phase is usually caused
by excessive clearance due to differential gear wear, or by a damaged
tooth on the coast side of the pinion or ring gear. Even a very small
tooth nick or a ridge on the edge of a gear tooth is enough the cause
the noise.
This condition can be corrected simply by cleaning the gear
tooth nick or ridge with a small grinding wheel. If either gear is
damaged or scored badly, the gear set must be replaced. If metal has
broken loose, the carrier and housing must be cleaned to remove
particles that could cause damage.
Knock
This is very similar to a chuckle, though it may be louder,
and occur on acceleration or deceleration. Knock can be caused by a
gear tooth that is damaged on the drive side of the ring and pinion
gears. Ring gear bolts that are hitting the carrier casting can cause
knock. Knock can also be due to excessive end play in the axle shafts.
Clunk
Clunk is a metallic noise heard when an automatic
transmission is engaged in Reverse or Drive, or when throttle is
applied or released. It is caused by backlash somewhere in the
driveline, but not necessarily in the axle. To determine whether
driveline clunk is caused by the axle, check the total axle backlash
as follows:
1) Raise vehicle on a frame or twinpost hoist so that drive
wheels are free. Clamp a bar between axle companion flange and a part
of the frame or body so that flange cannot move.
2) On conventional drive axles, lock the left wheel to keep
it from turning. On all models, turn the right wheel slowly until it
is felt to be in Drive condition. Hold a chalk marker on side of tire
about 12" from center of wheel. Turn wheel in the opposite direction
until it is again felt to be in Drive condition.
3) Measure the length of the chalk mark, which is the total