Lexus SC300 / Lexus SC400. Manual - part 702

9. 

FILL ENGINE WITH COOLANT (See page 

CO–7

)

10.  FILL COOLING FAN RESERVOIR TANK WITH FLUID

(See pages 

CO–23

 and 24)

11.  CHECK AUTOMATIC TRANSMISSION FLUID LEVEL

(See page 

MA–11

)

NOTICE: Do not overfill.

12.  START ENGINE AND CHECK FOR LEAKS
13.  INSTALL ENGINE UNDER COVER

–

COOLIING SYSTEM

Radiator

CO–21

ELECTRONICALLY CONTROLLED HYDRAULIC COOLING FAN

Description

In this way system, the cooling fan ECU controls the hydraulic pressure acting on the hydraulic motor, thus

controlling the speed of the cooling fan steplessly in response to the condition of the engine and air conditioner.

Operation

The hydraulic pump is driven by a drive belt (V–ribbed belt). The solenoid valve adjusts the volume of oil

sent from the hydraulic pump to the hydraulic motor which drives the fan directly, thereby controlling the fan
speed.

Oil which has passed through the hydraulic motor is cooled by the oil cooler before returning to the reservoir

tank.

The solenoid valve is controlled by the computer in accordance with the E/G rpm, water temp. and A/C

signals.

CO–22

–

COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Description, Operation)

On–Vehicle Inspection

INSPECTION OF DRIVE BELT

(See step 1 on page 

CH–5

)

INSPECTION OF FLUID LEVEL

1. 

KEEP VEHICLE LEVEL

2. 

INSPECT FLUID LEVEL
(a)  Using SST, connect terminals OP1 and E1 of the check

(”DIAGNOSIS”) connector.

SST 09843–18020
HINT: When terminals OP1 and E1 are connected, the circuit
of the water temp. sensor is grouded, fixing the fan speed at
approx. 1,100 rpm. (Fail–safe operation occurs.)

(b)  Keep the engine speed at 2,000 rpm until the fluid

temperature reaches the specified temperature.

Fluid temp.: 70–90

°

C (158–195

°

F)

(c)  Check that there is no foaming and emulsification of the

fluid in the reservoir tank.

(d)  Measure the fluid level with the engine running.
(e)  Stop the engine, and measure the fluid level.
(f)  Subtract (d) from (e).

Maximum stroke: 5 mm (0.20 in.)

(g)  Check the fluid level.
If low, add fluid.

Fluid: ATF DEXRON II

HINT: Check that fluid level is within the ”HOT” level on reser-
voir tank. If the fluid is cold, check that it is within the ”COLD”
level on the tank.
(h)  Remove the SST from the check connector.
SST 09843–18020

–

COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (On–Vehicle Inspection)

CO–23

BLEEDING OF HYDRAULIC COOLING
SYSTEM

1. 

CHECK FLUID LEVEL IN RESERVOIR TANK
If low, add fluid.

Fluid: ATF DEXRON II

HINT: Check that fluid level is within the ”HOT” level on reser-
voir tank. If the fluid is cold, check that it is within the ”COLD”
level on the tank.

2. 

BLEED COOLING SYSTEM
(a)  Using SST, connect terminals OP1 and E1 of the check

(”DIAGNOSIS”) connector.

SST 09843–18020
HINT: When terminals OP1 and E1 are connected, the circuit
of the water temp. sensor is grounded, fixing the fan speed
at approx. 1,100 rpm. (Fail–safe operation occurs.)
(b)  Start the engine without depressing the accelerator

pedal.

(c)  Leave the engine running for several seconds.
(d)  Check that there is no foaming and emulsification of the

fluid in the reservoir tank.

INSPECTION OF OIL PRESSURE

1. 

CONNECT PRESSURE GAUGE
(a)  Remove the union bolt and gasket, and disconnect the

pressure hose from the hydraulic motor.

(b) Connect 

the 

gauge side of a pressure gauge to pressure

hose, and the valve side to the hydraulic motor.

CO–24

–

COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (On–Vehicle Inspection)