1991 MITSUBISHI MONTERO lock

remains on (light may flash) during vehicle operation, cause of
malfunction must be determined by using DIAGNOSTIC FAULT CHARTS (if
testing with voltmeter) or diagnostic CODE CHARTS (if testing with
DRB-II). If a sensor fails, ECU will use a substitute value in its
calculations to continue engine operation. In this condition, vehicle
is functional, but loss of good driveability may result.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker
or illuminate and go out after the intermittent fault goes away.
However, the corresponding trouble code will be retained in ECU
memory. If related fault does not reoccur within a certain time frame,
related trouble code will be erased from ECU memory. Intermittent
failures may be caused by a sensor, connector or wiring related
problems. See INTERMITTENTS in H - TESTS W/O CODES article.
PRETEST INSPECTION
Before proceeding with diagnosis, the following precautions
must be followed:
* Vehicle must have a fully charged battery and functional
charging system.
* Visually inspect connectors and circuit wiring being worked
on.
* DO NOT disconnect battery or ECU. This will erase any fault
codes stored in ECU.
* DO NOT cause short circuits when performing electrical tests.
This will set additional fault codes, making diagnosis of original
problem more difficult.
* DO NOT use a test light in place of a voltmeter.
* When checking for spark, ensure coil wire is NO more than
1/4" from ground. If coil wire is more than 1/4" from ground,
damage to vehicle electronics and/or ECU may result.
* DO NOT prolong testing of fuel injectors. Engine may
hydrostatically (liquid) lock.
* When a vehicle has multiple fault codes, always repair lowest
number fault code first.
* If DRB-II is being used to diagnose system, always perform
verification test after repairs are made.
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER)
1) Before entering on-board diagnostics, refer to PRETEST
INSPECTION in this article. Turn ignition switch to OFF position.
Locate self-diagnostic connector. See SELF-DIAGNOSTIC TEST CONNECTOR
LOCATION table. Using an analog voltmeter, connect voltmeter positive
lead to self-diagnostic connector terminal No. 1 and negative lead to
terminal No. 12 (ground). See Fig. 6.
2) Turn ignition switch to ON position and disclosure of ECU
memory will begin. If 2 or more systems are non-functional, they are
indicated by order of increasing code number. Indication is made by
12-volt pulses of voltmeter pointer. A constant repetition of short
12-volt pulses indicates system is normal. If system is abnormal,
voltmeter will pulse between zero and 12 volts.
3) Signals will appear on voltmeter as long and short 12-volt
pulses. Long pulses represent tens; short pulses represent ones. For
example 4 long pulses and 3 short pulses indicates Code 43. See

Figs. 1 and 2. After recording abnormal code(s), perform necessary
repair.
4) After repair, turn ignition off and disconnect negative
battery cable for 10 seconds to erase ECU memory. Reconnect power
supply and repeat self-diagnostics to confirm repair.
SELF-DIAGNOSTIC TEST CONNECTOR LOCATION TABLE









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Application Location
Colt, Colt 200, Colt Wagon & Summit
1.5L ................................ Next to fuse block
1.6L .................................. Right kick panel
Colt Wagon & Colt Vista
1.8L & 2.0L SOHC .................... Next to fuse block
Eclipse ............................... Next to fuse block
Galant ................................... Left kick panel
Mirage ................................... Left kick panel
Montero .......................... Inside top of glove box
Precis ................................... Left kick panel









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Fig. 1: Diagnostic Fault Chart (1 of 2)
Courtesy of Mitsubishi Motor Sales of America.

input device usage on specific models, see appropriate wiring diagram
in M - WIRING DIAGRAMS.
Air Conditioner Switch
When A/C is turned on, signal is sent to ECU. With engine at
idle, ECU increases idle speed through Idle Speed Control (ISC) motor.\
Airflow Sensor
Incorporated in airflow sensor assembly, airflow sensor is a
Karmen Vortex-type sensor which measures intake airflow rate.
Intake air flows through tunnel in airflow sensor assembly.
Airflow sensor transmits radio frequency signals across direction of
incoming airflow, downstream of vortex. Intake air encounters vortex,
causing turbulence in tunnel.
Turbulence disrupts radio frequency, causing variations in
transmission. Airflow sensor converts frequency transmitted into a
proportionate electrical signal which is sent to ECU.
Airflow Sensor Assembly
Mounted inside air cleaner, incorporates airflow sensor,
atmospheric pressure sensor and intake air temperature sensor.
Atmospheric (Barometric) Pressure Sensor
Incorporated in the airflow sensor assembly, converts
atmospheric pressure to electrical signal which is sent to ECU. ECU
adjusts air/fuel ratio and ignition timing according to altitude.
Coolant Temperature Sensor
Converts coolant temperature to electrical signal for use by
ECU. ECU uses coolant temperature information for controlling fuel
enrichment when engine is cold.
Crankshaft Angle & TDC Sensor Assembly
Assembly is located in distributor on SOHC engines. On DOHC
engines, which use Direct (or Distributorless) Ignition System (DIS)\
,
assembly is separate unit mounted in place of distributor. Assembly
consists of triggering disc (mounted on shaft) and stationary optical
sensing unit. Camshaft drives shaft, triggering optical sensing unit.
ECU determines crank angle and TDC based on signals received from
optical sensing unit.
Detonation Sensor (Turbo Only)
Located in cylinder block, senses engine vibration during
detonation (knock). Sensor converts vibration into electrical signal.
ECU retards ignition timing based on this signal.
Engine Speed (Tach Signal)
ECU uses ignition coil tach signal to determine engine speed.
Idle Position Switch
On all DOHC engines and Sigma 3.0L, idle position switch is
separate switch mounted on throttle body. On all other models, idle
position switch is incorporated in ISC motor or throttle position
sensor, depending on vehicle application. When throttle valve is
closed, switch is activated. When throttle valve is at any other
position, switch is deactivated. This input from idle position switch
is used by ECU for controlling fuel delivery time during deceleration.
Ignition Timing Adjustment Terminal
Used for adjusting base ignition timing. When terminal is
grounded, ECU timing control function is by-passed, allowing base
timing to be adjusted.

NOTE: With switch removed, check continuity between switch
connector terminal and switch body. With switch installed,
check continuity between switch connector terminal and
transfer case.
4WD Indicator Light Switch (RAM-50)
With switch removed, check continuity between connector
terminal and switch body. With switch end pressed, there should be no
continuity. With switch end released, there should be continuity.
Center Differential Lock Operation Detection Switch (Montero)
Check continuity between terminals at Brown wire connector
terminal on top of transfer case. With transfer control lever in "4H"
position, there should be no continuity. With transfer control lever
in "4HLc" position, there should be continuity. See Fig. 2.
4WD Operation Detection Switch (Montero)
Check continuity between terminals at Black wire connector
terminal on top of transfer case. With transfer control lever in "2H"
position, there should be no continuity. With transfer control lever
in "4H" position, there should be continuity. See Fig. 2.
Center Differential Lock Detection Switch (Montero)
Check continuity between terminals at Brown wire connector
terminal on side of transfer case. With transfer control lever in "4H"
position, there should be no continuity. With transfer control lever
in "4HLc" position, there should be continuity. See Fig. 2.
2WD-4WD Detection Switch (Montero)
Check continuity between terminals at Black wire connector
terminal on side of transfer case. With transfer control lever in "4H"
position, there should be no continuity. With transfer control lever
in "2H" position, there should be continuity. See Fig. 2.
HI/LO Detection Switch (Montero)
Check continuity between terminals at White wire connector
terminal on side of transfer case. With transfer control lever in "N"
(between "4HLc" and "4LLc") position, there should be no continuity.
With transfer control lever in "4HLc" position, there should be
continuity. With transfer control lever in "4LLc" position, there
should be continuity. See Fig. 2.

2) Remove 2 seal plugs. Remove 2 poppet springs and steel
balls. Shift transfer case to "4WD" and pull high-low shift rail out,
in rear cover direction. Remove interlock plunger. Remove pulse
generator (if equipped), front output shaft cover and pulse rotor (if\
equipped). Remove snap ring from rear bearing on output shaft. Remove
chain cover, oil guide and side cover. Remove countershaft locking
plate. Remove countershaft.
3) Remove countergear, 2 thrust washers, 2 needle bearings
and spacer through side cover opening. Remove snap ring, spring
retainers and spring from 2WD-4WD shift rail. Remove front output
shaft, rear output shaft and chain as assembly.
4) Remove 2WD-4WD shift fork and distance piece. Drive out
2WD-4WD shift rail spring pin. Remove 2WD-4WD shift rail and lug.
Remove high-low shift fork and high-low synchronizer sleeve. Remove
needle bearing and snap ring from input gear. Remove input gear
assembly.
5) If either control shaft or input gear oil seals are to be
replaced, drive out roll pin from transmission control change shifter.
Separate transfer case from adapter. See Fig. 3.
Disassembly (Montero)
1) Remove dynamic damper, 5 detection switches and 3 steel
balls. Remove poppet plug, spring and steel ball. Remove speedometer
gear assembly. Remove output shaft rear cover, spacers, dust seal
guard and oil seals. Front output shaft cover, wave spring and spacer
(if equipped).
2) Remove high-low shift rail plug and high-low shift fork
spring pin. Shift transfer case to "4WD". Remove rear cover and high-
low shift rail. Remove interlock plunger. Remove rear output shaft
(viscous coupling) assembly and center differential assembly. Remove
2WD-4WD synchronizer assembly, chain and front output shaft from
transmission as a unit. With White paint make match marks in grooves
of 2WD-4WD synchronizer in 3 places. With White paint make match marks
on spline projections of 2WD-4WD synchronizer sleeve in 3 places.
Refer to match marks during reassembly.
3) Remove snap ring, spring seat, spring, 2WD-4WD shift fork
and 2WD-4WD synchronizer sleeve. Remove differential lock hub, oil dam
cover and bearing retainer. Remove side cover and gasket. Remove
transfer counter gear shaft, transfer counter gear, thrust washer,
needle bearings and spacer. Remove transfer drive shaft assembly.
Remove high-low shift fork assembly and clutch sleeve. Remove transfer
input gear assembly.
4) Remove 2WD-4WD shift lug spring pin, spring, spring
retainer 2WD-4WD shift lug and shift rail. Remove input gear oil seal,
baffle plate, dust seal guard and front output shaft oil seal. See
Fig. 4 .
COMPONENT DISASSEMBLY & REASSEMBLY
OUTPUT SHAFT ASSEMBLY (MONTERO)
Disassembly & Reassembly (Rear Shaft)
Remove snap ring and press ball bearing off without putting
pressure on vicious coupling. Remove viscous coupling. To install,
reverse removal procedure. When installing new snap ring, select
thickest ring that will fit into groove. Acceptable clearance is 0-.
003" (0-.08 mm).
Disassembly & Reassembly (Front Shaft)
Remove front bearing. Remove rear bearing. To install reverse
removal procedure.

OUTPUT SHAFT ASSEMBLY (RAM-50)
Disassembly
1) Remove snap ring from rear of output shaft. Remove high-
low synchronizer hub by hand or when low speed gear is pressed off.
Remove bearing spacer and needle bearing. Remove staking from lock nut
on rear output shaft. See Fig. 5. Remove lock nut. Remove ball bearing
from below lock nut. Remove sprocket spacer and steel ball.
2) Remove drive sprocket, 2 needle bearings, sprocket sleeve
and steel ball. Remove 2WD-4WD synchronizer sleeve, hub, stopper plate
and ball bearing.
Reassembly
1) Press ball bearing and stopper plate on front output
shaft, pushing against inner race. After fitting, ensure bearing
rotates smoothly. Install 2WD-4WD synchronizer hub and sleeve. Ensure
hub and sleeve face correct direction. Install steel ball (for
sprocket sleeve positioning) on rear output shaft. Install sprocket
sleeve.
2) Install 2 needle bearings on outer circumference of
sprocket sleeve. Install drive sprocket. Install steel ball and
sprocket spacer. Install ball bearing (press may not be needed as
bearing may be loose). Check for smooth rotation.
3) Tighten sprocket retaining lock nut to specification. See
the TORQUE SPECIFICATIONS table. Stake lock nut with punch. After lock
nut is tightened, ensure drive sprocket rotates smoothly. Install
needle bearing, thrust washer and low speed gear on rear of rear
output shaft.
4) Install needle bearing, thrust washer and low speed gear
on rear output shaft. Mount high-low synchronizer hub. Ensure hub
faces correct direction.
5) Mount high-low synchronizer hub snap ring on front end of
rear output shaft. Selective fit snap rings are available in 5
thicknesses. Use thickest snap ring that will fit into output shaft
groove. Acceptable clearance is 0-.003" (0-.08 mm). See Fig. 5.
Fig. 5: Exploded View Of Output Shaft Assembly (Ram-50)
Courtesy of Mitsubishi Motor Sales of America.
TRANSFER DRIVE SHAFT (MONTERO)

1) Install input gear and front output shaft oil seals into
transfer case housing. Pack grease between lips of seals and press
seal circumference uniformly.
2) Install input gear assembly in transfer case. See Figs. 3
and 6. Input gear assembly snap ring is available in selective
thicknesses. Use thickest snap ring that will fit into input shaft
groove. Allowed snap ring clearance is 0-.0024" (0-.060 mm).
3) Insert needle bearing onto rear output shaft assembly.
Install high-low synchronizer sleeve and shift fork. Install 2WD-4WD
shift fork. Engage chain securely on front and rear output shaft
sprockets. Assemble 2WD-4WD synchronizer sleeve with 2WD-4WD shift
fork. Install assembly over 2WD-4WD shift rail. Install front and rear
output shafts with chain as an assembly.
4) Install 2WD-4WD shift lug, distance piece, 2WD-4WD shift
rail and spring pin. Ensure slit in spring pin is in line with 2WD-4WD
shift rail. Install 2 spring retainers with spring on 2WD-4WD shift
rail. Install snap ring to end of 2WD-4WD shift rail. See Fig. 3.
5) Insert 2 needle bearings and spacer into countergear.
Install one thrust washer at each end of countergear. Ensure tab on
thrust washers fits into groove of transfer case. Install countergear
shaft assembly with "O" ring.
6) Install side cover and gasket. Install oil guide. Apply
sealant to both sides of gasket and install gasket and chain cover.
Ensure oil guide end fits into chain cover opening. Fit snap ring into
groove of rear bearing on rear output shaft. Tighten bolts to
specification. See TORQUE SPECIFICATIONS .
7) Install interlock plunger. Shift 2WD-4WD shift rail to 4WD
position. Install high-low shift rail through high-low shift fork in
case. Install 2 poppet balls and springs. Install seal plugs. When
installing poppet springs, smaller end must be toward ball.
8) On models with pulse generator, install pulse rotor, wave
spring and spacer. Measure protrusion "A" of front output shaft rear
bearing and recess "B" of cover and calculate clearance. See Fig. 9.
If clearance is greater than .079" (2.0 mm), select and install spacer\
to bring clearance within specification. If clearance is less than .
079" (2.0 mm), use wave spring alone. Apply sealant to both sides of
gasket and install gasket and cover. Install pulse generator (if
equipped).
9) On all models, align high-low shift fork and shift rail
spring holes and drive in roll pin with punch. Roll pin should be
installed with slit on center line of shift rail. Install wave spring
on rear of rear output shaft bearing. Apply sealant to both sides of
rear cover gasket. Install gasket and cover.
10) Check output shaft end play. Measure protrusion "A" of
rear output shaft rear bearing and recess "B" of cover and calculate
clearance. Ensure end play is 0-.004" (0-.10 mm). Apply sealant to
both sides of gasket and install gasket and cover. See Fig. 9.
11) Install speedometer sleeve assembly in rear cover. Align
match mark on speedometer sleeve assembly in rear cover. See Fig. 10.
Align match mark on speedometer sleeve with mark on case according to
number of teeth on speedometer driven gear. Install speedometer driven
gear sleeve clamp and tighten bolt to specification. Install both 4WD
indicator light switches with steel balls. See TORQUE SPECIFICATIONS.

Fig. 10: Aligning Speedometer Sleeve
Courtesy of Mitsubishi Motor Sales of America.
Reassembly (Montero)
1) Install input gear and front output shaft oil seals into
transfer case housing. Install transfer input gear assembly baffle
plate and input gear seal. Pack grease between lips of seals and press
seal circumference uniformly.
2) Install 2WD-4WD shift lug into transfer case. Install
spring retainer and spring to shift rail and install into shift lug.
Press on shift rail to align spring pin holes in shift rail and shift
lug. While holding shift rail, tap spring pin into place with slit
facing center of shift rail.
3) Install transfer input gear assembly and snap ring. Select
thickest snap ring that will fit into groove. Allowed snap ring
clearance is 0-.0024" (0-.060 mm). Insert needle bearing onto transfer\
drive shaft assembly. Install high-low synchronizer sleeve and shift
fork assembly. Install transfer drive shaft assembly.
4) Install transfer countergear shaft thrust washers, needle
bearings, bearing spacer and transfer countergear. Install one thrust
washer at each end of transfer countergear. Ensure tab on thrust
washers fits into groove of transfer case. Install counter gear shaft
from transmission case side so lock plate groove is aligned with lock
plate. Install lock plate. Install side cover and gasket.
5) Install bearing retainer. If reusing bearing retainer
bolts, apply Locking Adhesive (3M 4170 Stud Lock) to threads. Install
oil dam cover. Install differential lock hub, snap ring, steel ball
and sleeve. Select thickest snap ring that will fit into groove.
Allowed snap ring clearance is 0-.003" (0-.08 mm). Install 2WD-4WD
synchronizer sleeve, 2WD-4WD shift fork, spring, spring seat and 2WD-