2000 LEXUS GS400 Service Repair Manual

B02035
ECT Switch
Connector
ECT
Switch
O±Ring
CO0AJ±01
P05962
Ohmmeter
± COOLING (2JZ±GE)ENGINE COOLANT TEMPERATURE (ECT) SWITCH
CO±31
1569 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ENGINE COOLANT
TEMPERATURE (ECT) SWITCH
INSPECTION
1. DRAIN ENGINE COOLANT
2. REMOVE ECT SWITCH
(a) Disconnect the connector.
(b) Remove the ECT switch.
(c) Remove the O±ring from the ECT switch.
3. INSPECT ECT SWITCH
(a) Using an ohmmeter, check that there is no continuity be-
tween the terminals when the coolant temperature is
above 93°C (199°F).
If there is continuity, replace the switch.
(b) Using an ohmmeter, check that there is continuity be-
tween the terminals when the coolant temperature is be-
low 83°C (181°F).
If there is no continuity, replace the switch.
4. REINSTALL ECT SWITCH
(a) Install a new O±ring to the ECT switch.
(b) Install the ECT switch.
(c) Connect the connector.
5. REFILL WITH ENGINE COOLANT
6. START ENGINE AND CHECK FOR COOLANT LEAKS

B01376
Radiator
Fan Main
RelayCO0AK±01
B00019
Ohmmeter
Continuity
OhmmeterOhmmeter
No Continuity
Continuity21
5
43
B00020
Ohmmeter Ohmmeter
No Continuity
Continuity 2
1
5
43
Battery
CO±32
± COOLING (2JZ±GE)RADIATOR FAN MAIN RELAY
1570 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
RADIATOR FAN MAIN RELAY
INSPECTION
1. REMOVE RELAY BOX COVER
2. REMOVE RADIATOR FAN MAIN RELAY (Marking:
RAD FAN MAIN)
3. INSPECT RADIATOR FAN MAIN RELAY
(a) Inspect the relay continuity.
(1) Using an ohmmeter, check that there is continuity
between terminals 3 and 5.
If there is no continuity, replace the relay.
(2) Check that there is continuity between terminals 2
and 4.
If there is no continuity, replace the relay.
(3) Check that there is no continuity between terminals
1 and 2.
If there is continuity, replace the relay.
(b) Inspect the relay operation.
(1) Apply battery positive voltage across terminals 3
and 5.
(2) Using an ohmmeter, check that there is no continu-
ity between terminals 2 and 4.
If there is continuity, replace the relay.
(3) Check that there is continuity between terminals 1
and 2.
If there is no continuity, replace the relay.
4. REINSTALL RADIATOR FAN MAIN RELAY
5. REINSTALL RELAY BOX COVER

B00924
No.1 Cooling
Fan RelayCO0AL±01
B00021
Ohmmeter
Continuity
OhmmeterContinuity
41
3
2
B00022
No Continuity Ohmmeter
41
3
2
Battery
B01373
No.2 Cooling
Fan Relay
A00970
Continuity
Ohmmeter
No Continuity Continuity4
1
32
Ohmmeter
5
Ohmmeter
± COOLING (2JZ±GE)COOLING FAN RELAY
CO±33
1571 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
COOLING FAN RELAY
INSPECTION
1. INSPECT NO.1 COOLING FAN RELAY
(a) Remove the relay box cover.
(b) Remove the No.1 cooling fan relay. (Marking: FAN NO.1)
(c) Inspect the No.1 cooling fan relay continuity.
(1) Using an ohmmeter, check that there is continuity
between terminals 1 and 2.
If there is no continuity, replace the relay.
(2) Check that there is continuity between terminals 3
and 4.
If there is no continuity, replace the relay.
(d) Inspect the No.1 cooling fan relay operation.
(1) Apply battery positive voltage across terminals 1
and 2.
(2) Using an ohmmeter, check that there is no continu-
ity between terminals 3 and 4.
If there is continuity, replace the relay.
(e) Reinstall the No.1 cooling fan relay.
(f) Reinstall the relay box cover.
2. INSPECT NO.2 COOLING FAN RELAY
(a) Remove the relay box cover.
(b) Remove the No.2 cooling fan relay. (Marking: FAN NO.2)
(c) Inspect the No.2 cooling fan relay continuity.
(1) Using an ohmmeter, check that there is continuity
between terminals 1 and 2.
If there is no continuity, replace the relay.
(2) Check that there is continuity between terminals 3
and 4.
If there is no continuity, replace the relay.
(3) Check that there is no continuity between terminals
3 and 5.
If there is continuity, replace the relay.

A00971
Ohmmeter
No ContinuityOhmmeter
Continuity 4
1
32
5
Battery
B01375
No.3 Cooling
Fan Relay
A00968No ContinuityContinuity 12 Ohmmeter
5Ohmmeter
3
A00969
Ohmmeter
Continuity1
32
5
Battery
CO±34
± COOLING (2JZ±GE)COOLING FAN RELAY
1572 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(d) Inspect the No.2 cooling fan relay operation.
(1) Apply battery positive voltage across terminals 1
and 2.
(2) Using an ohmmeter, check that there is no continu-
ity between terminals 3 and 4.
If there is continuity, replace the relay.
(3) Using an ohmmeter, check that there is continuity
between terminals 3 and 5.
If there is no continuity, replace the relay.
(e) Reinstall the No.2 cooling fan relay.
(f) Reinstall the relay box cover.
3. INSPECT NO.3 COOLING FAN RELAY
(a) Remove the relay box cover.
(b) Remove the No.3 cooling fan relay. (Marking: FAN NO.3)
(c) Inspect the No.3 cooling fan relay continuity.
(1) Using an ohmmeter, check that there is continuity
between terminals 1 and 2.
If there is no continuity, replace the relay.
(2) Check that there is no continuity between terminals
3 and 5.
If there is continuity, replace the relay.
(d) Inspect the No.3 cooling fan relay operation.
(1) Apply battery positive voltage across terminals 1
and 2.
(2) Using an ohmmeter, check that there is continuity
between terminals 3 and 5.
If there is no continuity, replace the relay.
(e) Reinstall the No.3 cooling fan relay.
(f) Reinstall the relay box cover.

CO09Z±03
A02725Turn
Loosen
B01614
Water Bypass Outlet
No.1 Water Bypass Hose
B01638
Clamp Bracket
Connector Bracket
B01572No.2 Water Bypass Pipe
± COOLING (2JZ±GE)WATER PUMP
CO±5
1543 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REMOVAL
1. REMOVE RADIATOR ASSEMBLY
(See page CO±18)
2. REMOVE DRIVE BELT AND WATER PUMP PULLEY
(a) Loosen the 4 nuts holding the water pump pulley to the
water pump.
(b) Loosen the drive belt tension by turning the drive belt ten-
sioner clockwise, and remove the drive belt.
(c) Remove the 4 nuts and water pump pulley.
3. REMOVE TIMING BELT AND IDLER PULLEY
(See page EM±16)
4. REMOVE WATER BYPASS OUTLET AND NO.1
WATER BYPASS PIPE
(a) Remove the 2 bolts, water bypass outlet and No.1 water
bypass pipe.
(b) Remove the 3 O±rings from the water bypass outlet and
No.1 water bypass pipe.
5. REMOVE WATER INLET AND THERMOSTAT
(See page CO±11)
6. REMOVE WATER PUMP
(a) Loosen the nut and remove the bolt, slide the generator
away from the water pump.
(b) Remove the bolt, and disconnect the clamp bracket (for
engine wire).
(c) Remove the bolt, and disconnect the connector bracket
(for crankshaft position sensor connector).
(d) Remove the 2 nuts, and disconnect the No.2 water by-
pass pipe from the water pump.

B01941
Drain Hose
CO±6
± COOLING (2JZ±GE)WATER PUMP
1544 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(e) Remove the 6 bolts, water pump and gasket.
(f) Remove the drain hose.
(g) Remove the O±ring from the cylinder block.

CO0A0±01
B01574
± COOLING (2JZ±GE)WATER PUMP
CO±7
1545 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
INSPECT WATER PUMP
Turn the pulley seat, and check that the water pump bearing is
not rough or noisy.
If necessary, replace the water pump.

CO0A1±03
P03945
New
O±Ring
P02574
New Gasket
A02801
AB A
B
A
B
B
B
B01614
New O±Ring
CO±8
± COOLING (2JZ±GE)WATER PUMP
1546 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSTALLATION
1. INSTALL WATER PUMP
(a) Install a new O±ring to the cylinder block.
(b) Install the drain hose.
(c) Install a new gasket to the water pump.
(d) Connect the water pump to the water bypass pipe. Do not
install the nut yet.
(e) Install the water pump with the 2 bolts (A) and 4 bolts (B).
Torque: 21 N´m (210 kgf´cm, 15 ft´lbf)
HINT:
Hand tighten the (A) bolts first.
(f) Install the 2 nuts holding the No.2 water bypass pipe to
the water pump.
Torque: 21 N´m (210 kgf´cm, 15 ft´lbf)
(g) Install the connector bracket (for crankshaft position sen-
sor connector) with the bolt.
(h) Install the clamp bracket (for engine wire) with the bolt.
(i) Install the generator with the bolt and nut.
Torque: 40 N´m (400 kgf´cm, 30 ft´lbf)
2. INSTALL THERMOSTAT AND WATER INLET
(See page CO±13)
3. INSTALL NO.1 WATER BYPASS PIPE AND WATER
BYPASS OUTLET
(a) Install 2 new O±rings to the No.1 water bypass pipe.
(b) Install a new O±ring and the water bypass outlet with the
2 bolts.
Torque: 9.0 N´m (90 kgf´cm, 80 in.´lbf)
4. INSTALL IDLER PULLEY AND TIMING BELT
(See page EM±23)
5. INSTALL WATER PUMP PULLEY AND DRIVE BELT
Torque: 14 N´m (140 kgf´cm, 10 ft´lbf)