1998 MITSUBISHI MONTERO ECU

Check defogger switch or defogger timer. See COMPONENT TESTS.
INDICATOR LIGHT DOES NOT WORK
Check for burned out bulb, open circuit or poor connection.
INDICATOR LIGHT IS DIM
Check rheostat or indicator bulb.
SYMPTOM TESTS
INPUT SIGNAL INSPECTION
NOTE: The following information only applies to Eclipse and Galant.
NOTE: Perform input signal inspection before proceeding with
SYSTEM TESTS .
Eclipse & Galant
1) Input signal inspection can be performed using scan tool
or an analog voltmeter. To perform inspection using scan tool, go to
next step. To perform inspection using an analog voltmeter, go to step
3).
2) Turn ignition off. Connect scan tool to Data Link
Connector (DLC). Turn ignition on and then off. If buzzer on scan tool\
sounds when ignition was turned on, ECU input signal is normal. If
buzzer did not sound, go to SYSTEM TESTS.
3) Turn ignition off. Connect DTC Check Harness (MB991529) t\
o
DLC terminals No. 4 or 5 (ground) and terminal No. 9. See Fig. 1.
Connect voltmeter leads to check harness leads. Turn ignition switch
on, then off. If voltmeter deflects once when ignition was turned on,
ECU input signal is normal. If voltmeter did not deflect, go to
SYSTEM TESTS .
Fig. 1: Identifying Data Link Connector (DLC) Terminals
Courtesy of Mitsubishi Motor Sales of America
SYSTEM TESTS

NOTE: The following information only applies to Eclipse and Galant.
NOTE: Perform INPUT SIGNAL INSPECTION before proceeding with
SYSTEM TESTS. To identify circuit connector terminals, see
WIRING DIAGRAMS .
Communication With All Systems Not Possible (Eclipse &
Galant)
1) Check voltage between ground and Data Link Connector (DLC)\
terminal No. 16 (Red/Black wire on Eclipse or Brown/Red wire on
Galant). See Fig. 1. If battery voltage is present, go to step 3). If
battery voltage is not present, go to next step.
2) Check junction block connectors between DLC and power
supply. See WIRING DIAGRAMS . If connectors are okay, check circuit
between power supply and DLC. See WIRING DIAGRAMS. Repair as
necessary.
3) Check continuity between ground and DLC terminals No. 4
and 5. If continuity is present, replace scan tool and retest. If
continuity is not present, check circuit between ground and DLC. See
WIRING DIAGRAMS . Repair as necessary.
Communication With One-Shot Pulse Input Signal Only Is Not
Possible (Eclipse & Galant)
Check circuit between DLC and junction block No. 1. See
WIRING DIAGRAMS . Repair as necessary. If circuit is okay, check
harness connectors to ETACS-ECU, DLC and junction/joint connectors.
Repair as necessary. If connectors are okay, replace ECU.
Defogger Does Not Operate With Defogger Switch ON (Eclipse &
Galant)
1) Check defogger switch input signal. See
INPUT SIGNAL INSPECTION . If switch input signal is okay, check
defogger circuit and relay. See DEFOGGER RELAY TEST under COMPONENT
TESTS. Repair or replace as necessary. If switch input signal is not
okay, go to next step.
2) Check defogger switch. See DEFOGGER SWITCH TEST under
COMPONENT TESTS. Replace as necessary. If defogger switch is okay,
turn ignition on. Check voltage between ground and defogger switch
harness-side connector terminal No. 4 (Eclipse) or terminal No. 2
(Galant). See WIRING DIAGRAMS . If voltage reading is 5 volts (Eclipse)
or battery voltage (Galant), go to next step. If voltage reading is
not as specified, go to step 4).
3) Check joint/junction connectors between switch, instrument
panel cluster and ETACS-ECU. See WIRING DIAGRAMS. Repair as necessary.
If connectors are okay, check circuit between defogger switch and
ground. Repair as necessary. If circuit is okay, replace ECU.
4) Check harness connectors to ETACS-ECU and instrument panel
cluster. Repair as necessary. If connectors are okay, check circuit
between ECU and defogger switch. Repair as necessary.
Defogger Relay Circuit System Check (Eclipse & Galant)
1) Check defogger relay. See DEFOGGER RELAY TEST under
COMPONENT TESTS. Replace as necessary. If relay is okay, go to next
step.
2) Check voltage between ground and relay harness-side
connector terminals No. 3 and 5. See WIRING DIAGRAMS. If battery
voltage is present, go to next step. If battery voltage is not
present, go to step 4).
3) Check harness connectors to relay, ETACS-ECU, junction
block and rear wiring/liftgate. See WIRING DIAGRAMS. Repair as
necessary. If connectors are okay, check circuit between defogger
relay and rear defogger, defogger and ground, or defogger relay and
ECU. See WIRING DIAGRAMS . Repair as necessary. If circuits are okay,

replace ECU.
4) Check harness connectors to junction block and ignition
switch. Repair as necessary. If connectors are okay, check circuit
between ignition switch and junction block, and between fusible link
No. 2 and junction block. See WIRING DIAGRAMS. Repair as necessary.
COMPONENT TESTS
DEFOGGER RELAY TEST
Diamante & Eclipse
1) Remove defogger relay. See COMPONENT LOCATIONS. Ground
relay terminal No. 1, and apply battery voltage to terminal No. 3. See
Fig. 2 . Check relay continuity using ohmmeter.
2) Continuity should exist between terminals No. 2 and 5.
With voltage disconnected, continuity should not exist between
terminals No. 2 and 5. Ensure continuity exists between terminals No.
1 and 3. If continuity is not as specified, replace relay.
Galant, Mirage & Montero Sport
1) Remove defogger relay. See COMPONENT LOCATIONS. Ground
relay terminal No. 3, and apply battery voltage to terminal No. 1. See
Fig. 2 . Check relay continuity using ohmmeter.
2) Continuity should exist between terminals No. 2 and 5.
With voltage disconnected, continuity should not exist between
terminals No. 2and 5. Ensure continuity exists between terminals No. 1
and 3. If continuity is not as specified, replace relay.
Montero
1) Remove defogger relay. See COMPONENT LOCATIONS. Ground
relay terminal No. 3 and apply battery voltage to terminal No. 1. See
Fig. 3 . Check relay continuity using ohmmeter.
2) Continuity should exist between terminals No. 4 and 5.
With voltage disconnected, continuity should not exist between
terminals No. 4and 5. Ensure continuity exists between terminals No. 1
and 3. If continuity is not as specified, replace relay.
3000GT
1) Remove defogger relay. See COMPONENT LOCATIONS. Ground
relay terminal No. 3, and apply battery voltage to terminal No. 5. See
Fig. 4 . Check relay continuity using ohmmeter.
2) Continuity should exist between terminals No. 1 and 2.
With voltage disconnected, continuity should not exist between
terminals No. 1and 2. Ensure continuity exists between terminals No. 3
and 5. If continuity is not as specified, replace relay.
Fig. 2: Identifying Defogger Relay Terminals (Diamante, Eclipse,
Galant, Mirage & Montero Sport)
Courtesy of Mitsubishi Motor Sales of America

NOTE: Remove window defogger switch and disconnect switch
connector for the following test.
Diamante
Rear window defogger is integral with and controlled by A/C
system ECU. To diagnose system, refer to AIR CONDITIONING & HEATING
SERVICE & REPAIR article.
Eclipse
Turn defogger switch to OFF position. Using ohmmeter, check
switch continuity. Continuity should be present between terminals No.
1 and 3, and terminals No. 2 and 6. Turn defogger switch to ON
position. Continuity should be present between terminals No. 1, 3 and
4, and between terminals No. 2 and 6. See Fig. 5. If continuity is not
as specified, replace switch.
Galant
Turn defogger switch to OFF position. Using ohmmeter, check
switch continuity. Continuity should be present between terminals No.
1 and 3. Turn defogger switch to ON position. Continuity should exist
between terminals No. 2, 4 and 6, and between terminals No. 1 and 3.
See Fig. 5 . If continuity is not as specified, replace switch.
Mirage
Turn defogger switch to OFF position. Using ohmmeter, check
switch continuity. Continuity should be present between terminals No.
1 and 3, and terminals No. 2 and 6. Turn defogger switch to ON
position. Continuity should exist between terminals No. 1 and 3, and
terminals No. 2, 4, 5 and 6. See Fig. 5. If continuity is not as
specified, replace switch.
Montero
Turn defogger switch to OFF position. Using ohmmeter, check
switch continuity. Continuity should be present between terminals No.
1 and 3, and terminals No. 4 and 5. Turn defogger switch to ON
position. Continuity should exist between terminals No. 1 and 3,
terminals No. 4 and 5, and between terminals No. 2 and 6. See Fig. 5.
If continuity is not as specified, replace switch.
Montero Sport
Turn defogger switch to OFF position. Using ohmmeter, check
switch continuity. Continuity should be present between terminals No.
1 and 5, and terminals No. 2 and 6. Turn defogger switch to ON
position. Continuity should be present between terminals No. 3 and 4,
terminals No. 1 and 5, and between terminals No. 2 and 6. See Fig. 5.
If continuity is not as specified, replace switch.
3000GT
1) Remove defogger switch assembly from instrument cluster
bezel. With defogger switch in OFF position, check switch continuity
using ohmmeter.
2) Continuity should exist between terminals No. 3 and 4.
With defogger switch in ON position, continuity should exist between
terminals No. 1 and 2, terminals No. 1 and 6, and between terminals
No. 3 and 4. See Fig. 6. If continuity is not as specified, replace
switch.
Fig. 5: Identifying Defogger Switch Terminals (Eclipse, Galant,
Mirage, Montero & Montero Sport)
Courtesy of Mitsubishi Motor Sales of America

1) Start and run engine at 2000 RPM. Ensure battery is fully
charged. Turn defogger switch to ON position. Using a voltmeter, check
voltage at center section of each defogger grid filament.
2) If voltage is about 6 volts, grid filament is okay. If
voltage is about 12 volts, an open is present in negative circuit.
Move probe slowly toward negative terminal to determine location of
open circuit.
3) If voltage is zero volts, an open is present in positive
circuit. Move probe slowly toward positive terminal to determine
location of open circuit. Repair grid as necessary. See
GRID FILAMENT REPAIR under ON-VEHICLE SERVICE.
ON-VEHICLE SERVICE
GRID FILAMENT REPAIR
Clean broken wire tips thoroughly. Place masking tape along
both sides of broken wire. See Fig. 8. Apply Repair Paste (DuPont
4817) to broken section of grid. Remove masking tape after paste has
dried. Wait 24 hours before using defogger.
Fig. 8: Repairing Rear Defogger Grid Element
REMOVAL & INSTALLATION
DEFOGGER SWITCH
Removal & Installation (Diamante)
Defogger switch is integral with A/C system ECU. To remove
A/C ECU, remove center console. Remove audio panel. Remove radio.
Remove A/C ECU. To install, reverse removal procedure.
Removal & Installation (Eclipse)
Remove upper stoppers from glove compartment. Drop down glove
compartment. From glove compartment opening, reach behind center air
outlet assembly and disconnect harness connectors to switches. Release
metal clips from center air outlet assembly. Remove center air outlet.
Remove defogger switch from center air outlet. To install, reverse
removal procedure.
Removal & Installation (Galant)

Fig. 11: Rear Window Defogger System Wiring Diagram (Galant With
ETACS-ECU)

Fig. 12: Rear Window Defogger System Wiring Diagram (Galant Without
ETACS-ECU)

Check ring gear, pinion and side gears for wear or damage. Replace
components as necessary.
Reassembly & Adjustments
1) Place side gear thrust spacers behind side gears, in
original position. Assemble side gears in differential case. Install
pinion gears and washers. Rotate pinion gears to mesh with side gears.
2) Install pinion shaft without lock pin. Check pinion and
side gear backlash. Install wooden wedge to lock side gears. Using
dial indicator, measure gear backlash. See Fig. 5.
3) Backlash must be within specification. See
PINION & SIDE GEAR BACKLASH SPECIFICATIONS table. Adjust backlash by
using different side gear spacers. Ensure both sides are equally
shimmed. If backlash cannot be adjusted within specifications, replace
side and pinion gears as matched set.
4) Install pinion shaft lock pin. Using a punch, securely
stake lock pin in 2 places. Ensure adhesive is removed from ring gear
mounting bolts and gear mounting surface. Clean internal threads with
tap.
5) Install ring gear on differential case. Ensure alignment
marks on differential case and ring gear are aligned. Apply Loctite
271 to bolts and install bolts. Tighten bolts alternately in diagonal
sequence to specification. See TORQUE SPECIFICATIONS.
PINION & SIDE GEAR BACKLASH SPECIFICATIONS









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Application In. (mm)\
Standard ................................................ .003 (.08)\
Wear Limit .............................................. .008 (.20)\









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Fig. 5: Checking Pinion & Side Gear Backlash
Courtesy of Mitsubishi Motor Sales of America.
Drive Pinion Depth
1) Install pinion bearing races in carrier housing. Ensure