ECU MITSUBISHI MONTERO 1998 Workshop Manual

* PLEASE READ THIS FIRST *
NOTE: Self-diagnostics should be performed when cruise control
cancels without driver using normal cancel modes.
RETRIEVING CODES
1) Data Link Connector (DLC) is located to left of steering
column. Use analog voltmeter or scan tool for code retrieval. Follow
scan tool manufacturer's instructions.
2) Using an analog voltmeter, connect leads between cruise
control terminal and ground terminal of DLC. See Fig. 35. Count number
of deflections and pauses of voltmeter needle to determine trouble
code. Digit count is about 0.5 second per pulse and pause between
digits is about 2 seconds. Once trouble codes have been displayed, see
DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION table.
DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION TABLE









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Code Diagnostic Item
11 .............................. Vacuum Pump Drive System
12 ........................... Vehicle Speed Sensor Signal
14 ....................... Vacuum Pump Power Supply System
15 ................................. Cruise Control Switch
16 .................................... Cruise Control ECU
17 ....................... Throttle Position Sensor System









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Fig. 35: Identifying Data Link Connector Terminals
Courtesy of Mitsubishi Motor Sales of America
CLEARING CODES

1) To clear trouble codes, disconnect battery cable, or use
alternative method to prevent memory loss.
2) Turn ignition on. Turn main cruise control switch and SET
switch to ON position, and within one second, turn RES switch to ON
position. Hold stoplight switch and cruise control switch in ON
position for greater than 5 seconds. Verify codes are cleared.
DIAGNOSTIC TESTS
CODE 11: VACUUM PUMP DRIVE SYSTEM
Code 11 is displayed if release valve, control valve and
motor drive signals from vacuum pump are not input to cruise control
ECU. Probable causes are:
* Malfunction of vacuum pump.
* Malfunction of stoplight switch.
* Malfunction of connector.
* Malfunction of harness.
* Malfunction of cruise control ECU.
1) Check vacuum pump. See VACUUM PUMP TEST under COMPONENT
TESTS. If vacuum pump is defective, replace vacuum pump. If vacuum
pump is okay, go to next step.
2) Disconnect cruise control actuator harness connector A-57
or A-95. See Fig. 5. At harness side of connector, check voltage
between terminal No. 1 and ground. If battery voltage is present, go
to next step. If battery voltage is not present, check stoplight
switch. See BRAKELIGHT/STOPLIGHT SWITCH TEST under COMPONENT TESTS.
Replace switch if defective. Check cruise control main switch harness
connector C-01 and stoplight switch harness connector C-55. Repair as
necessary. If malfunction remains, check harness between cruise
control main switch and vacuum pump. Repair as necessary.
3) Disconnect cruise control ECU connector C-50. See Fig. 13.
At harness side of connector, check voltage between ground and
terminals No. 12 (driving release valve), No. 13 (driving control
valve), and No. 26 (driving motor). If battery voltage is present, go\
to next step. If battery voltage is not present, check and repair
connectors A-57 or A-95 and C-111 as necessary. See Figs. 5 and 24. If
malfunction remains, check and repair harness between vacuum pump and
cruise control ECU as necessary.
4) Check cruise control ECU connector C-50. Repair as
necessary. If malfunction remains, replace cruise control ECU.
CODE 12: VEHICLE SPEED SENSOR SIGNAL
Code 12 is displayed if vehicle speed signals from vehicle
speed sensor are not input to cruise control ECU when vehicle speed is
25 MPH or more. Probable causes are:
* Malfunction of VSS.
* Malfunction of connector.
* Malfunction of harness.
* Malfunction of cruise control ECU.
1) Check vehicle speed sensor. See VEHICLE SPEED SENSOR TEST
under COMPONENT TESTS. If speed sensor is okay, go to next step. If
speed sensor is defective, repair or replace as necessary.
2) Disconnect combination meter connector C-06. See Fig. 10.
At harness side of connector, with ignition switch in ON position,
measure voltage between terminal No. 1 and ground. If voltage is 4.5
volts or more, go to next step. If voltage is less than 4.5 volts,

check cruise control ECU connector C-50 and joint connector C-130.
Repair as necessary. See Figs. 13, 16 and 28. If malfunction remains,
check harness between combination meter (instrument cluster) and
cruise control ECU. Repair as necessary.
3) Disconnect combination meter connector C-04. See Fig. 9.
Check for continuity at harness side between terminal No. 43 and
ground. If continuity is present, go to next step. If continuity is
not present, check harness between combination meter and ground.
Repair as necessary.
4) Inspect combination meter connector C-04. If connector is
defective, repair as necessary. If connector is okay and malfunction
remains, replace cruise control ECU.
CODE 14: VACUUM PUMP POWER SUPPLY
Code 14 is displayed when drive signals for vacuum pump
release valve, control valve and motor are not input into cruise
control ECU. Probable causes are:
* Malfunction of stoplight switch.
* Malfunction of connector.
* Malfunction of harness.
* Malfunction of cruise control ECU.
1) Disconnect vacuum pump connector A-105. See Fig. 6. At
harness side of connector, check voltage between terminal No. 1 and
ground. If battery voltage is present, go to next step. If battery
voltage is not present, check stoplight switch. See
BRAKELIGHT/STOPLIGHT SWITCH TEST under COMPONENT TESTS. Replace as
necessary. If switch is okay, check connectors to combination meter,
stoplight switch and vacuum pump. Repair as necessary. If connectors
are okay and malfunction remains, check and repair circuit between
cruise control ECU and vacuum pump. If malfunction remains, replace
cruise control ECU.
2) Check connectors and circuit between cruise control ECU
and vacuum pump. See WIRING DIAGRAMS. Repair as necessary. If
connectors and circuit are okay, replace cruise control ECU.
CODE 15: CRUISE CONTROL SWITCH
Code 15 is displayed if RESUME switch or SET switch remains
on. Probable cause is malfunction of cruise control switch. Replace
cruise control switch.
CODE 16: CRUISE CONTROL ECU
Code 16 is displayed if there is an abnormality in CANCEL
hold circuit or microprocessor monitor circuit in cruise control ECU.
Probable cause is malfunction of cruise control ECU. Replace cruise
control ECU.
CODE 17: THROTTLE POSITION SENSOR
Code 17 is displayed if a voltage of 1.5 volts or more exists
when closed throttle position switch is ON or 0.2 volt or less exists
when closed throttle position switch is OFF for a continuous period of
4 seconds or more. Probable causes are:
* Malfunction of throttle position sensor.
* Malfunction of connector.
* Malfunction of harness.
* Malfunction of cruise control ECU.

1) If PCM DTC P0120 (engine performance code) is also set,
see
CLOSED THROTTLE POSITION SWITCH TEST & THROTTLE POSITION SENSOR TEST
under COMPONENT TESTS. If DTC P0120 is not set, go to next step.
2) Check cruise control ECU connector C-50. If connector is
okay, go to next step. If connector is defective, repair as necessary.
3) If malfunction remains, inspect harness between throttle
position sensor and cruise control ECU. Repair as necessary. If
harness is okay, replace cruise control ECU.
PIN VOLTAGE TESTS
Fig. 36: Pin Voltage Chart (1 Of 2)
Courtesy of Mitsubishi Motor Sales of America

* PLEASE READ THIS FIRST *
WARNING: Deactivate air bag system before performing any service
operation. See AIR BAG RESTRAINT SYSTEMS article. Do not
apply electrical power to any component on steering column
without first deactivating air bag system. Air bag may
deploy.
ACTUATOR
Removal & Installation
Disconnect cruise control cable from link. Disconnect
actuator wiring connector. Remove vacuum pump and vacuum pump bracket.
Remove actuator and actuator bracket. To install, reverse removal
procedure.
CRUISE CONTROL ECU
Removal & Installation
Cruise control ECU is located behind center of dash panel.
Remove center trim panel and radio or radio plug bezel. Remove control
unit. To install, reverse removal procedure.
CRUISE CONTROL SWITCH
Removal & Installation
Remove lower steering column cover. Disconnect electrical
connectors. Remove screws attaching cruise control switch to steering
column. Remove switch. To install, reverse removal procedure.
INSTRUMENT CLUSTER
Removal & Installation
Disconnect negative battery cable. Remove cluster cover.
Disconnect speedometer cable. Remove instrument cluster. To install,
reverse removal procedure.
WIRING DIAGRAMS

DEFOGGER - REAR WINDOW
1998 Mitsubishi Montero
1998 ACCESSORIES & EQUIPMENT
Mitsubishi - Rear Window Defoggers
Diamante, Eclipse, Galant, Mirage, Montero, Montero Sport,
3000GT
DESCRIPTION & OPERATION
Rear window defogger is a heating filament grid bonded to
inside of window. Rear window defogger is controlled by defogger
switch on instrument panel and a defogger relay.
On Montero, a timer relay controls defogger operation for 9-
11 minutes, then turns defogger off. On Eclipse and Galant, defogger
timer circuit is integral with Electronic Timer Alarm Control System
(ETACS) ECU. Timer will operate defogger for 11 minutes then turn off,\
even with defogger switch in ON position and indicator light
illuminated. On Diamante, timer will operate defogger for 20 minutes,
then turn off.
COMPONENT LOCATIONS
COMPONENT LOCATIONS TABLE








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Component Location
A/C ECU
Diamante ......................... Behind Center Of Dash
Data Link Connector (DLC) ....... Under Left Side Of Dash,
Near Steering Column
Defogger Relay
Montero Sport ....................... Under Left Side Of
Glove Compartment
Except Montero Sport ................... On Relay Block,
Behind Left Side Of Dash
Defogger Timer
Diamante ......................... Integral With A/C ECU
Eclipse & Galant ............... Integral With ETACS-ECU
Montero ...................... Behind Left Side Of Dash,
Behind Speaker
ETACS-ECU ......................... Above Left Kick Panel,
On Junction Block









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TROUBLE SHOOTING
* PLEASE READ THIS FIRST *
NOTE: For additional trouble shooting information on Eclipse and
Galant, see SYMPTOM TESTS.
DEFOGGER DOES NOT WORK
Check for blown fuse, poor contact, defective defogger
switch, poor connection or open wire.
DEFOGGER TIMER INOPERATIVE

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