Mitsubishi 3000GT - From 1994 Models

CIRCUIT DIAGRAMS - Cooling Circuit 185
<From 1994 models>
OPERATION
The engine control module controls the power
transistors (high speed and low speed) in the module
to provide radiator fan motor and condenser fan
motor rotation controls in accordance with the engine
coolant temperature and vehicle speed.
NOTE
In the event of faulty water temperature sensor,
the engine control module commands the fan motors
(for both radiator and condenser) to rotate at high
speeds.
1. Radiator Fan (Low Speed Rotation)
l When the engine control module turns on
the power transistor (low speed) in the
module, the current flows from the ignition
switch to the engine control module through
the radiator fan motor relay (LO) coil.
If the current flows to the fan motor relay
coil, the switch of the relay turns on to supply
the motor driving power (for low speed
rotation). This will cause the current to flow
from the battery to the ground through the
radiator fan motor, relay switch and resistor,
rotating the radiator fan at low speeds.
2. Condenser Fan (Low Speed Rotation)
l
The power from the NC compressor lock
controller turns on the condenser fan motor
relay (LO) to rotate the condenser fan at
low speeds.
3. Radiator Fan, Condenser Fan (High
Speed Rotation)
l
When the engine control module turns on
the power transistor (high speed) in the
module. the radiator fan motor relay (HI)
and condenser fan motor relay (HI) will
operate and the motor driving power (for
high speed rotation) is sent to the radiator
fan motor and condenser fan motor to rotate
the radiator fan and condenser fan at high
speeds.
TROUBLESHOOTING HINTS
1. Neither the radiator fan nor condenser
fan rotate at all.
l Check fusible link No. 5.
2. Only the condenser fan does not
operate.
l Check dedicated fuse No. 8.
3. The condenser fan do not operate in the
low speed mode, but operate otherwise.
(1) The A/C compressor magnet clutch does
not enter the “ON” state.
l Check whether the output of the air
conditioning compressor lock controller
unit is available.
(2) The A/C compressor magnet clutch enters
the “ON” state.
l Check the condenser fan motor relay
(LO)-
4. The radiator fan and condenser fan do
not operate in the high speed mode, but
operate otherwise.
l Check the engine control unit.
Fan Operating Mode
Vehicle
A/C compressor lock
speed
controller output
k%
80 or less
[50 or less]
LO (OV)
80 or more
[50 or more]
HI (12V) ,_ -
Engine coolant
temperature
$1
Approx. 95 [203] or less
Approx. 95 [203] or more
Approx. 105 [221] or more
Approx. 105 [221] or less
Approx. 105 [221] or more
Approx. 105 [221] or less
Approx. 105 12211 or more
Transistor Transistor
in engine
in engine Radiator
Condenser
control unit
control unit fan fan
Low speed
High speed
OFF
OFF
OFF OFF
ON
OFF Low speed
OFF
ON
ON High speed
High speed
OFF
OFF
OFF
OFF
ON ON High speed
High speed
ON
OFF Low speed
Low speed
ON
ON
High speed
High speed
1 TSB Revision 1