
TROUBLESHOOTING
ENGINE COOLING14-7
CIRCUIT OPERATION
•The cooling fan motor drive control unit is
powered from fusible link (2).
•The engine-ECU
uses input signals from the A/C switch, the
water temperature sensor unit and the vehicle
speed sensor
sensor to control the speed of the cooling
fan motor (L.H.) and the cooling fan motor (R.H.)
<4G1 (Vehicles with A/C)> or A/C condenser fan
motor <4G6>.
•The engine-ECU
controls the cooling fan motor drive control
unit to activate the cooling fan motor (L.H.) and
the cooling fan motor (R.H.) <4G1 (Vehicles with
A/C)> or A/C condenser fan motor <4G6>.
TECHNICAL DESCRIPTION
•The cause could be a malfunction of the cooling
fan motor drive control unit power supply or earth
circuit.
•If the communication line wiring harness between
the cooling fan motor drive control unit and the
engine-ECU
short-circuited to earth, the cooling fan motor
(L.H.) and the cooling fan motor (R.H.) <4G1
(Vehicles with A/C)> or the A/C condenser fan
motor <4G6> will not rotate.
•The cause could also be a malfunction of the
cooling fan motor (L.H.).
•The cause could also be a malfunction of imput
signal from the A/C switch, the water temperature
sensor unit and the vehicle speed sensor
or the output shaft speed sensor to the
engine-ECU
•The cause could also be a malfunction of the
cooling fan motor drive control unit or the
engine-ECU
TROUBLESHOOTING HINTS
•Malfunction of fusible link (2)
•Malfunction of fan control relay
•Malfunction of cooling fan motor (L.H.)
•Malfunction of cooling fan motor drive control unit
•Malfunction of engine-ECU
engine-A/T-ECU
•Damaged wiring harness or connector
DIAGNOSIS
STEP 1. Check the cooling fan motor (L.H.).
Refer to P.14-25.
Q: Is the cooling fan motor (L.H.) in good condition?
YES :
Go to Step 2 .
NO : Replace the cooling fan motor (L.H.) (Refer
to P.14-35). Then go to Step 24 .
STEP 2. Measure the power supply voltage at
cooling fan motor drive control unit connector
A-18.
(1) Disconnect cooling fan motor drive control unit
connector A-18 and measure wiring harness side
connector.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between cooling fan motor
drive control unit connector A-18 terminal 3 and
body earth.
•The voltage should measure system voltage.
(4) Turn the ignition switch to the "LOCK" (OFF)
position.
(5) Connect cooling fan motor drive control unit
connector A-18.
Q: Is the measured voltage system voltage?
YES :
Go to Step 17 .
NO : Go to Step 3 .
AC100293
A-18
321
Connector: A-18
AD
AC000246AF
A-18 Connector
(Component side)

TROUBLESHOOTING
ENGINE COOLING14-12
STEP 15. Check the fan control relay connector
A-09X.
Q: Is the connector in good condition?
YES :
Go to Step 16 .
NO : Repair the connector or replace the relay
box. Then go to Step 24 .
STEP 16. Check the harness wire between fan
control relay connector A-09X terminal 3 and
body earth.
Q: Is the harness wire in good condition?
YES :
An intermittent malfunction is suspected
(Refer to GROUP 00 - How to use
troubleshooting P.00-5).
NO : Repair the damaged harness wire. Then go
to Step 24 .
STEP 17. Check the continuity between cooling
fan motor drive control unit connector A-18 and
body earth.
(1) Disconnect cooling fan motor drive control unit
connector A-18 and measure wiring harness side
connector.
(2) Measure the resistance between cooling fan
motor drive control unit connector A-18 terminal 1
and body earth.
•Continuity exists.
(3) Connect cooling fan motor drive control unit
connector A-18.
Q: Dose the continuity exists?
YES :
Go to Step 20 .
NO : Go to Step 18 .
AC303510AB
Fan control relay
Relay boxConnector: A-09X
A-09X
AC303510AB
Fan control relay
Relay boxConnector: A-09X
A-09X
AC100293
A-18
321
Connector: A-18
AD
AC303534AB
A-18 Connector
(Wiring harness side)

TROUBLESHOOTING
ENGINE COOLING14-16
INSPECTION PROCEDURE 2: Cooling Fan (L.H.) and Cooling Fan (R.H.) <4G1 (Vehicles with A/C)> or
A/C Condenser Fan <4G6> do not Change Speed or Stop
COOLING FAN (L.H.) AND COOLING FAN
(R.H.) OR A/C CONDENSER FAN DRIVE
CIRCUIT
Refer to P.14-6.
CIRCUIT OPERATION
Refer to P.14-6.
TECHNICAL DESCRIPTION
•If the communication line wiring harness between
the cooling fan motor drive control unit and the
engine-ECU
is open, the cooling fan motor (L.H.) and
the cooling fan motor (R.H.) <4G1 (Vehicles with
A/C)>, or the A/C condenser fan motor <4G6>
rotate to prevent the engine from overheating.
•If the system voltage is continuously supplied to
the cooling fan motor drive control unit by a fan
motor relay malfunction and a short circuit on the
cooling fan motor drive control unit power supply
wiring harness, the cooling fan motor (L.H.) and
the cooling fan motor (R.H.) <4G1 (Vehicles with
A/C)>, or the A/C condenser fan motor <4G6>
rotate.
•The cause could also be a malfunction of the
cooling fan motor (L.H.).
•The cause could also be a malfunction of input
signal from the A/C switch, the water temperature
sensor unit and the vehicle speed sensor
or the output shaft speed sensor to the
engine-ECU
•The cause could also be a malfunction of the
cooling fan motor drive control unit or the
engine-ECU
TROUBLESHOOTING HINTS
•Malfunction of fan control relay
•Malfunction of cooling fan motor (L.H.)
•Malfunction of cooling fan motor drive control unit
•Malfunction of engine-ECU
engine-A/T-ECU
•Damaged wiring harness or connector
DIAGNOSIS
STEP 1. Check the fan control relay.
Refer to P.14-24.
Q: Is the fan control relay in good condition?
YES :
Go to Step 2 .
NO : Replace the fan control relay. Then go to
Step 8 .
STEP 2. Check the fan control relay connector
A-09X.
Q: Is the connector in good condition?
YES :
Go to Step 3 .
NO : Repair the connector or replace the relay
box. Then go to Step 8 .
AC303510AB
Fan control relay
Relay boxConnector: A-09X
A-09X

THERMOSTAT
ENGINE COOLING14-27
REMOVAL SERVICE POINT
<> RADIATOR LOWER HOSE
DISCONNECTION
Make mating marks on the radiator lower hose and
the hose clamp. Disconnect the radiator lower hose.
INSTALLATION SERVICE POINTS
>>A<< THERMOSTAT INSTALLATION
CAUTION
Make absolutely sure that no oil adheres to the
rubber ring of the thermostat. Also do not fold or
scratch the rubber ring during installation.
Install the thermostat so that the jiggle valve is facing
straight up. Be careful not to fold or scratch the
rubber ring.
>>B<< RADIATOR LOWER HOSE
CONNECTION
1. Insert radiator lower hose as far as the projection
of the Cooling water inlet hose fitting.
2. Align the mating marks on the radiator lower hose
and hose clamp, and then connect the radiator
lower hose.
INSPECTIONM1141002500427
THERMOSTAT CHECK
1. Immerse the thermostat in water, and heat the
water while stirring. Check the thermostat valve
opening temperature.
Standard value:
88 ± 1.5°C <4G1>
82 ± 1.5°C <4G6>
Removal steps
1. Water temperature gauge unit
connector <4G6>
2. Water temperature sensor unit
connector <4G6>
<> >B<<3. Radiator lower hose connection4. Engine control oxygen sensor
connector and connector bracket
<4G1>
5. Control wiring harness clip <4G6>
6. Cooling water inlet hose fitting>>A<<7. ThermostatRemoval steps (Continued)
AC200641AC
Mating marks
AC000279
Jiggle valve
Rubber ring
AB
AC200642
Mating marks
Projection
Cooling water inlet
hse fitting
AH
ACX00400
AB

WATER HOSE AND WATER PIPE
ENGINE COOLING14-31
WATER HOSE AND WATER PIPE
REMOVAL AND INSTALLATION <4G1>M1141003300415
Pre-removal and Post-installation Operation
•Under Cover Removal and Installation
•Engine Coolant Draining and Supplying (Refer to
P.14-22).
•Air Cleaner Assembly Removal and Installation (Refer to
GROUP 15 P.15-3).
•Thermostat Removal and Installation (Refer to P.14-26).
AC203411
1 234
5 67
8
10 9
13 ± 2 N·m 23 ± 4 N·m
13 ± 2 N·m
N
N
AC
111213
N
Removal steps
1. Water temperature sensor unit
connector
2. Water temperature gauge unit
connector
3. Control wiring harness and harness
bracket
<> >>B<<4. Radiator upper hose connection
5. Throttle body water feed hose
6. Thermostat case assembly7. Thermostat case gasket
>>A<<8. Cooling water line O-ring
9. Control wiring harness clamp
10. Throttle body water return hose
11. Heater water hose connection
12. Water pump inlet pipe
>>A<<13. Cooling water line O-ringRemoval steps (Continued)

WATER HOSE AND WATER PIPE
ENGINE COOLING14-33
REMOVAL AND INSTALLATION <4G6>M1141003300426
Pre-removal and Post-installation Operation
•Engine Coolant Draining and Supplying (Refer to
P.14-22).
•Air Cleaner Assembly Removal and Installation (Refer to
GROUP 15 P.15-3).
•Thermostat Removal and Installation (Refer to P.14-26).
AC303471
1 23 4
56
7 8 9
9
13 ± 2 N·m
23 ± 4 N·m 13 ± 2 N·m
N
N
AB
2
Sealant: Mitsubishi Genuine Part No. MD970389 or equivalentØ3 mm
Ø3 mm
5
Removal steps
<> >>C<<1. Radiator upper hose connection
>>B<<2. Cooling water outlet hose fitting
3. Throttle body water return hose
4. Throttle body water feed hose
>>B<<5. Thermostat case assembly
6. Heater water hose connection7. Control wiring harness clamp
8. Water pump inlet pipe
>>A<<9. Cooling water line O-ringRemoval steps (Continued)

INLET MANIFOLD
INTAKE AND EXHAUST15-5
INLET MANIFOLD
REMOVAL AND INSTALLATION <4G1>M1151003000749
Pre-removal Operation
•Fuel Line Pressure Reduction (Refer to GROUP 13A -
On-vehicle Service P.13A-389).
•Engine Coolant Draining (Refer to GROUP 14 -
On-vehicle Service P.14-22).
•Strut Tower Bar Removal (Refer to GROUP 42 P.42-9).
•Throttle Body Assembly Removal (Refer to GROUP 13A
P.13A-400).
•Fuel Delivery Pipe and Fuel Injector Assembly Removal
(Refer to GROUP 13A P.13A-398).Post-installation Operation
•Fuel Delivery Pipe and Fuel Injector Assembly Installation
(Refer to GROUP 13A P.13A-398).
•Throttle Body Assembly Installation (Refer to GROUP
13A P.13A-400).
•Strut Tower Bar Installation (Refer to GROUP 42 P.42-9).
•Engine Coolant Supplying (Refer to GROUP 14 -
On-vehicle Service P.14-22).
•Accelerator Cable Adjustment (Refer to GROUP 17 -
On-vehicle Service P.17-2).
•Fuel Leak Check
AC303642AB
15
3
6
5
412 10 71
2
11
913
14
21 ± 4 N·m
9.0 ± 1.0 N·m
9.0 ± 1.0 N·m
18 ± 2 N·m
18 ± 2 N·m18 ± 2 N·m5.0 ± 1.0 N·m
31 ± 3 N·m
49 ± 9 N·m
N
N
N
8
Removal steps
1. Inlet manifold absolute pressure
sensor
2. Engine control pressure sensor
O-ring
3. Engine control detonation sensor
connector
4. T/M housing front lower cover stay
(L.H.)
5. Battery wiring harness clamp
connection
6. Inlet manifold stay
7. Brake booster vacuum hose
connection8. Emission control equip hose
connection
9. Fuel vapour control hose
connection
10. Inlet manifold stay
11. Inlet manifold
12. Inlet manifold gasket
13. EGR valve
14. EGR valve gasket
15. Emission vacuum hose & pipe and
emission solenoid valve assembly Removal steps (Continued)

EXHAUST MANIFOLD
INTAKE AND EXHAUST15-7
INSPECTIONM1151003100616
Check the following points; replace the part if a
problem is found.
Inlet Manifold Check
1. Check for damage or cracking of any part.2. Clogging of the negative pressure (vacuum) outlet
port, or clogging of the exhaust gas recirculation
passages.
3. Using a straight edge and feeler gauge, check for
distortion of the cylinder head installation surface.
Standard value: 0.15 mm or less
Limit: 0.20 mm
EXHAUST MANIFOLD
REMOVAL AND INSTALLATION <4G1>M1151003300568
8. Battery wiring harness clamp
9. Inlet manifold stay
10. Inlet manifold
11. Inlet manifold gasket
12. Emission vacuum hose & pipe and
emission solenoid valve assembly
13. EGR valve
14. EGR valve gasketRemoval steps (Continued)
AC30366250 ± 10 N·m 24 ± 4 N·m
35 ± 6 N·m17 ± 2 N·m 29 ± 3 N·m
N
3
7
12 4
N
6
8
44 ± 5 N·m
AB
9
5N
29 ± 3 N·m
29 ± 3 N·m
29 ± 3 N·m
(Engine oil)