Lexus SC300 / Lexus SC400. Manual - part 712

INSPECTION OF COOLING FAN ECU

1. 

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after 20 seconds or longer
from the time the ignition switch is turned to the ”LOCK” posi-
tion and the negative (–) terminal cable is disconnected from
the battery.

2. 

DISCONNECT COOLING FAN ECU CONNECTOR
(See Components on page 

CO–60

)

(a)  Remove the instrument panel under cover.
(b)  Remove the lower instrument panel finish panel and

glove compartment door assembly.

(c)  Disconnect the cooling fan ECU connector.

3. 

INSPECT COOLING FAN ECU
(a)  Connect the cable to the negative (–) terminal of the

battery.

(b)  Check the connector on the wiring harness side as

shown in the chart.

Check for

Tester connection

Condition

Specified value

Voltage

1–Ground

Ignition switch ON

Battery voltage

Resistance

2–3

Solenoid valve at cold (20

°

C (68

°

F))

7.5–8.5 

Continuity

4–Ground

–

Continuity

Continuity

5–Ground

Throttle valve open

No continuity

Continuity

5–Ground

Throttle valve closed

Continuity

Resistance

9–10

Coolant temp. at 80

°

C (176

°

F)

1.48–1.58 k

(c)  Disconnect the cable from the negative (–) terminal of

the battery.

4. 

RECONNECT COOLING FAN ECU CONNECTOR

5.  RECONNECT CABLE TO NEGATIVE TERMINAL OF

BATTERY

–

COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)

CO–61

 (Water Temperature Sensor)

COMPONENTS FOR REMOVAL AND
INSTALLATION

INSPECTION OF WATER TEMPERATURE
SENSOR

1. 

DISCONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY
CAUTION: Work must be started after 20 seconds or
longer from the time the ignition switch is turned to the
”LOCK” position and the negative (–) terminal cable is
disconnected from the battery.

2. 

REMOVE ENGINE UNDER COVER

3. 

DRAIN ENGINE COOLANT (See page 

CO–6

)

4. REMOVE 

WATER 

TEMPERATURE 

SENSOR

(a)  Disconnect the water temperature sensor connector.
(b)  Remove the water temperature sensor from left side of

the radiator lower tank.

(c)  Remove the O–ring from the water temperature sensor.

CO–62

–

COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)

5. INSPECT 

WATER 

TEMPERATURE 

SENSOR

Using an ohmmeter, measure the resistance between the ter-
minals.

Resistance: 1.48–1.58 k

 at 80

°

C (176

°

F)

If the resistance is not as specified, replace the sensor.

6. REINSTALL 

WATER 

TEMPERATURE 

SENSOR

(a)  Install a new O–ring to the water temperature sensor.
(b)  Apply soapy water to the O–ring.
(c)  Install the water temperature sensor to the radiator.

Torque: 7.4 N

⋅

m (75 kgf

⋅

cm, 65 in.

⋅

lbf)

(d)  Connect the water temperature sensor connector.

7. 

REFILL WITH ENGINE COOLANT (See page 

CO–7

)

8. 

REINSTALL ENGINE UNDER COVER

9. 

RECONNECT CABLE FROM NEGATIVE TERMINAL OF
BATTERY

(A/C High–Pressure Switch)

INSPECTION OF A/C HIGH–PRESSURE
SWITCH

1. 

DISCONNECT HIGH–PRESSURE SWITCH CONNECTOR

2. 

INSTALL MANIFOLD GAUGE SET (See AC section)

3. 

INSPECT HIGH–PRESSURE SWITCH
(a)  When the A/C switch is OFF, check that there is

continuity between terminals 2 and 3. (When the
pressure is 1,226 kPa (12.5 kgf/cm

2

, 178 psi) or lower.)

(b)  When the A/C switch and blower switch are ON, check

that there is no continuity between terminals 2 and 3.
(When the pressure is 1,520 kPa (15.5 kgf/cm

2

, 220 psi)

or higher.)

If continuity is not as specified, replace the switch.

4. 

REMOVE MANIFOLD GAUGE SET

5. 

RECONNECT HIGH–PRESSURE SWITCH CONNECTOR

(Solenoid Valve)

(See page 

CO–36

)

–

COOLIING SYSTEM

Electronically Controlled Hydraulic
Cooling Fan (Electronic Control Parts)

CO–63

SERVICE SPECIFICATIONS

SERVICE DATA

Thermostat

Valve opening temperature

80–84

°

C

176–183

°

F

Valve lift

at 95

°

C (203

°

F)

10 mm

0.39 in.

Radiator cap

Relief valve opening pressure

STD

74–103 kPa

(0.75–1.05 kgf/cm, 10.7–14.9 psi)

Limit

59 kPa

0.6 kgf/cm

8.5 psi

On–vehicle 
i

ti

f

h

Oil pressure

1,177–2,452 kPa

inspection for hy-
draulic cooling

(12–25 kgf/cm, 171–356 psi)

draulic cooling
fan

fan

Hydraulic pump

Spool valve

45.8 mm

1.803 in.

Rotor side clearance

STD

Drive rotor

0.02 mm

0.0008 in.

Driven rotor

0.03 mm

0.0012 in.

Limit

Drive rotor

0.03 mm

0.0012 in.

Driven rotor

0.04 mm

0.0016 in.

Rotor body clearance

STD

0.05–0.09 mm

0.0020–0.0035 in.

Limit

0.10 mm

0.0039 in.

Rotor tip clearance

STD

0.02 mm

0.0008 in.

Limit

0.03 mm

0.0012 in.

Drive shaft bushing inside diameter

17.00–17.05 mm

0.6693–0.6713 in.

Drive shaft diameter

16.97–16.98 mm

0.6681–0.6685 in.

Drive shaft oil clearance

STD

0.02–0.08 mm

0.0008–0.0031 in.

Limit

0.08 mm

0.0031 in.

Drive shaft preload (rotating torque)

0.3 N

⋅

m

3.0 kgf

⋅

cm

2.6 in.

⋅

lbf

Solenoid valve resistance

at cold

7.5–8.5 

Hydraulic motor

Rotor side clearance

STD

0.01–0.04 mm

0.0004–0.0016 in.

Limit

0.05 mm

0.0020 mm

Drive shaft hole inside diameter

14.000–14.011 mm

0.5512–0.5516 in.

Drive shaft diameter

13.973–13.984 mm

0.5501–0.5506 in.

Drive shaft oil clearance

STD

0.016–0.038 mm

0.0006–0.0015 in.

Limit

0.04 mm

0.0031 in.

Drive shaft preload (rotating torque)

0.3 N

⋅

m

3.0 kgf

⋅

cm

2.6 in.

⋅

lbf

Water temp. 

Resistance

at 80

°

C (176

°

F)

1.48–1.58 k

sensor

CO–64

–

COOLIING SYSTEM

Service Specifications