Mitsubishi 380. Manual — part 230
ENGINE COOLING DIAGNOSIS
ENGINE COOLING
14-4
INSPECTION PROCEDURE 2: Engine Overheating
DIAGNOSIS
STEP 1. Remove the radiator cap and check for coolant
contamination.
Q: Is the coolant contaminated with rust and oil?
YES : Replace it. Refer to
NO : There is no action to be taken. Go to Step 2.
STEP 2. Check the radiator cap valve opening pressure.
NOTE: Be sure that the cap is clean before testing. Rust or
other foreign material on the cap seal will cause an improper
reading.
(1) Use a cap adapter to attach the cap to the tester.
(2) Increase the pressure until the gauge indicator stops
moving.
Minimum limit: 83 kPa (12 psi)
Standard value: 93
− 123 kPa (14 − 18 psi)
Q: Does the reading remain at or above the minimum limit?
YES : Go to Step 3.
NO : Replace the radiator cap. Then go to Step 5.
STEP 3. Check thermostat operation.
Refer to 38.
Q: Does the thermostat operate correctly?
YES : Go to Step 4.
NO : Replace the thermostat, then go to Step 5.
STEP 4. Check the drive belt for slippage or damage.
Refer to GROUP 00, Maintenance Service
− Drive Belts
(Check Condition). <3.8L Engine>39 .
Q: Is the drive belt loose or damaged?
YES : Adjust or replace the drive belt, then go to Step 5.
NO : There is no action to be taken.
STEP 5. Retest the system.
Check the engine coolant temperature.
Q: Is the engine coolant temperature abnormally high?
YES : Return to Step 2.
NO : The procedure is complete.
ACX01845 AB
CAP ADAPTER
ENGINE COOLING DIAGNOSIS
ENGINE COOLING
14-5
INSPECTION PROCEDURE 3: Radiator Fan and Condenser Fan do not Operate
.
CIRCUIT OPERATION
• The fan controller is powered from fusible link
No.2.
• The engine-ECU uses input signals from the A/C
switch, the water temperature sensor unit and the
vehicle speed sensor <M/T> or the output shaft
speed sensor <A/T> to control the speed of the
radiator fan motor and the condenser fan motor.
• The engine-ECU controls the fan controller to
activate the radiator fan motor and the condenser
fan motor.
.
TECHNICAL DESCRIPTION
• The cause could be a malfunction of the fan con-
troller power supply or earth circuit.
• If the communication line wiring harness between
the fan controller and the engine-ECU is
short-circuited to earth, the radiator fan motor
and the condenser fan motor will not rotate.
• 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 <M/T>
or the output shaft speed sensor <A/T> to the
engine-ECU.
• The cause could also be a malfunction of the fan
controller or the engine-ECU.
.
TROUBLESHOOTING HINTS
• Malfunction of fusible link No.2
• Malfunction of fan control relay
• Malfunction of cooling fan motor and fan control-
ler
• Malfunction of engine-ECU.
• Damaged wiring harness or connector
• Refer to component locations GROUP-1
• Refer to configuration diagrams GROUP-1
ENGINE COOLING DIAGNOSIS
ENGINE COOLING
14-6
DIAGNOSIS
STEP 1. Measure the power supply voltage at fan
controller connector A-24.
(1) Disconnect fan controller connector A-24 and measure
wiring harness side connector.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between fan controller connector A-24
terminal 3 and body earth.
• The voltage should measure system voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Connect fan controller connector A-24.
Q: Is the measured voltage system voltage?
YES : Go to Step 17.
NO : Go to Step 2.
STEP 2. Check the fan controller connector A-24.
Q: Is the connector in good condition?
YES : Go to Step 3.
NO : Repair or replace the connector. Then go to Step 24.
04DB008A
1
2
3
A-24
Connector: A-24
3 2 1
04DB009A
Connector A-24
(Component side)
04DB008A
1
2
3
A-24
Connector: A-24
ENGINE COOLING DIAGNOSIS
ENGINE COOLING
14-7
STEP 3. Check the fusible link No.2.
Q: Is the fusible link No.2 in good condition?
YES : Go to Step 4.
NO : Replace the fusible link No.2. Then go to Step 24.
STEP 4. Measure the power supply voltage at fan control
relay connector A-10X.
(1) Disconnect fan control relay connector A-10X (remove the
fan control relay) and measure relay box side connector.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between fan control relay connector
A-10X terminal 4 and body earth.
• The voltage should measure system voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
(5) Connect fan control relay connector A-10X (install the fan
control relay).
Q: Is the measured voltage system voltage?
YES : Go to Step 7.
NO : Go to Step 5.
04DB010A
Fusible link
No.2
Relay box
Fan control
relay
04DB012A
Fusible link
No.2
Relay box
Fan control
relay
A-10X
4
04DB013A
A-10X Connector
(Relay box side)
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