2000 LEXUS GS400 relay

I04097
Battery Ignition
SwitchWarning Light
Wire Harness Side
I04098
Wire Harness Side
I04099
BatteryIgnition
SwitchWarning Light
Wire Harness Side BE±100
± BODY ELECTRICALCOMBINATION METER
2401 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
23. INSPECT REAR LIGHTS WARNING LIGHT
(See page DI±841)
(a) Disconnect the connector from the light failure sensor and
ground terminal 3 on the wire harness side connector.
(b) Start the engine, check that the warning light lights up.
If the warning light does not light up, inspect the bulb or wire har-
ness.
24. INSPECT LIGHT FAILURE SENSOR CIRCUIT
Disconnect connector from the light failure sensor and inspect
the connectors on the wire harness side as follows.
Tester connectionConditionSpecified condition
1 ± GroundConstantContinuity *
2 ± GroundConstantContinuity *
6 ± GroundConstantContinuity *
7 ± GroundConstantContinuity *
11 ± GroundConstantContinuity
12 ± GroundConstantContinuity *
5 ± GroundLight control switch OFFNo voltage
5 ± GroundLight control switch in TAIL or HEADBattery positive voltage
8 ± GroundIgnition switch in LOCK or ACCNo voltage
8 ± GroundIgnition switch ONBattery positive voltage
9, 10 ± GroundStop light switch OFFNo voltage
9, 10 ± GroundStop light switch ONBattery positive voltage
*: There is resistance because this circuit is grounded through
the bulb.
If circuit is as specified, replace the relay.
If circuit is not as specified, wiring diagram and inspect the cir-
cuits connected to other parts.
25. INSPECT ENGINE OIL LEVEL WARNING LIGHT
(a) Disconnect the connector from the switch.
(b) Run the engine.
(c) Turn the ignition switch ON, check that the warning light
lights up approximatery 40 seconds later.
If the warning light does not light up, inspect bulb or wire har-
ness.

B01900
CO0AD±03
B00922
ECT
Switch
Connector
B02072
B02073
Ammeter
Battery(+)
(±)
CO±24
± COOLING (2JZ±GE)ELECTRIC COOLING FAN
1562 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ELECTRIC COOLING FAN
ON±VEHICLE INSPECTION
1. CHECK COOLING FAN OPERATION WITH LOW
TEMPERATURE (Below 83°C (181°F))
(a) Turn the ignition switch ON.
(b) Check that the cooling fan stops.
If not, check the cooling fan relay and ECT switch, and check
for a separated connector or severed wire between the cooling
fan relay and ECT switch.
(c) Disconnect the ECT switch connector.
(d) Check that the cooling fan rotates.
If not, check the fuses, radiator fan main relay, cooling fan relay,
cooling fan, and check for a short circuit between the cooling
fan relay and ECT switch.
(e) Reconnect the ECT switch connector.
2. CHECK COOLING FAN OPERATION WITH HIGH
TEMPERATURE (Above 93°C (199°F))
(a) Start the engine, and raise coolant temperature to above
93°C (199°F).
HINT:
Coolant temperature is the detected value by the ECT switch
on the radiator lower tank.
(b) Check that the cooling fan rotates.
If not, replace the ECT switch.
3. INSPECT COOLING FANS
(a) Disconnect the cooling fan connector.
(b) Connect battery and ammeter to the cooling fan connec-
tor.
(c) Check that the cooling fan rotates smoothly, and check
the reading on the ammeter.
Standard amperage: 8.5 ± 11.5 A at 20°C (68°F)
(d) Reconnect the cooling fan connector.

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.

V07268
VIBRATION METHOD: When vibration seems to be the major cause.
CONNECTORS
WIRE HARNESS
PARTS AND SENSOR1
Slightly shake the connector vertically and horizontally.
Slightly shake the wire harness vertically and horizontally.
The connector joint, fulcrum of the vibration, and body
through portion are the major areas to be checked thorough-
ly.
Apply slight vibration with a finger to the part of the sensor
considered to be the problem cause and check that the mal-
function occurs.Shake Slightly
Swing Slightly
Vibrate Slightly
HINT:
Applying strong vibration to relays may result in open relays.
± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMSIN±25
25 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
3. SYMPTOM SIMULATION
The most difficult case in troubleshooting is when there are no problem symptoms occurring. In such cases,
a thorough customer problem analysis must be carried out, then simulate the same or similar conditions and
environment in which the problem occurred in the customer's vehicle. No matter how much experience a
technician has, or how skilled he may be, if he proceeds to troubleshoot without confirming the problem
symptoms he will tend to overlook something important in the repair operation and make a wrong guess
somewhere, which will only lead to a standstill. For example, for a problem which only occurs when the en-
gine is cold, or for a problem which occurs due to vibration caused by the road during driving, etc., the prob-
lem can never be determined so long as the symptoms are confirmed with the engine hot condition or the
vehicle at a standstill. Since vibration, heat or water penetration (moisture) is likely cause for problem which
is difficult to reproduce, the symptom simulation tests introduced here are effective measures in that the ex-
ternal causes are applied to the vehicle in a stopped condition.
Important Points in the Symptom Simulation Test:
In the symptom simulation test, the problem symptoms should of course be confirmed, but the problem area
or parts must also be found out. To do this, narrow down the possible problem circuits according to the symp-
toms before starting this test and connect a tester beforehand. After that, carry out the symptom simulation
test, judging whether the circuit being tested is defective or normal and also confirming the problem symp-
toms at the same time. Refer to the problem symptoms table for each system to narrow down the possible
causes of the symptom.

IN±28± INTRODUCTIONHOW TO TROUBLESHOOT ECU CONTROLLED
SYSTEMS
28 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
5. PROBLEM SYMPTOMS TABLE
The suspected circuits or parts for each problem symptom are shown in the table below. Use this table to
troubleshoot the problem when a ºNormalº code is displayed in the diagnostic trouble code check but the
problem is still occurring. Numbers in the table indicate the inspection order in which the circuits or parts
should be checked.
HINT:
When the problem is not detected by the diagnostic system even though the problem symptom is present,
it is considered that the problem is occurring outside the detection range of the diagnostic system, or that
the problem is occurring in a system other than the diagnostic system.
Symptom
Suspect AreaSee page
Engine does not crank (Does not start)
No initial combustion (Does not start)
No complete combustion (Does not start)1. Starter and starter relay
1. ECM power source circuit
2. Fuel pump control circuit
3. Engine control module (ECM)
1. Starter signal circuit
2. Fuel pump control circuit1. Fuel pump control circuitDI±147
DI±151
IN±29
PROBLEM SYMPTOMS TABLE
1. Compression
2. Fuel pump control circuit 1. A/C signal circuit
2. Fuel pump control circuit 1. A/C signal circuit (Compressor circuit)
2. ECM power source circuit 1. Starter signal circuit
2. Fuel pump control circuit1. Starter signal circuit
2. Fuel pump control circuit
3. Compression
idling) High engine idle speed (Poor idling) Hot engine Cold engine (Difficult to start)Engine cranks normally (Difficult to start)
AC±88 DI±144
DI±151
EM±3 DI±151

Problem Symptom
Page
Indicates the page where the flow chart for each circuit
is located.

Circuit Inspection, Inspection Order
Indicates the circuit which needs to be checked for each problem
symptom. Check in the order indicated by the numbers.

Circuit or Part Name
Indicates the circuit or part which needs to be checked.
ST±2
ST±17
DI±144
DI±151
DI±144
DI±151

± INTRODUCTIONTERMS
IN±39
39 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) OEM
Original Equipment Manufacturing
OHCOverhead Camshaft
OHVOverhead Valve
OPTOption
O/SOversize
P & BVProportioning And Bypass Valve
PCSPower Control System
PCVPositive Crankcase Ventilation
PKBParking Brake
PPSProgressive Power Steering
PSPower Steering
PTOPower Take±Off
R & PRack And Pinion
R/BRelay Block
RBSRecirculating Ball Type Steering
R/FReinforcement
RFSRigid Front Suspension
RHRight±Hand
RHDRight±Hand Drive
RLYRelay
ROMRead Only Memory
RrRear
RRRear±Engine Rear±Wheel Drive
RRSRigid Rear Suspension
RWDRear±Wheel Drive
SDNSedan
SENSensor
SICSStarting Injection Control System
SOCState Of Charge
SOHCSingle Overhead Camshaft
SPECSpecification
SPISingle Point Injection
SRSSupplemental Restraint System
SSMSpecial Service Materials
SSTSpecial Service Tools
STDStandard
STJCold±Start Fuel Injection
SWSwitch
SYSSystem
T/ATransaxle
TACHTachometer
TBIThrottle Body Electronic Fuel Injection
TCTurbocharger
TCCSTOYOTA Computer±Controlled System
TCVTiming Control Valve
TDCTop Dead Center