2000 LEXUS GS400 Service Repair Manual

I04080
Connector
ºOº, ºPº, ºQº, ºRº BE±94
± BODY ELECTRICALCOMBINATION METER
2395 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)F5 (±) ± F12 (+)
A/T shift indicator light (R)Continuity
F2 (±) ± F12 (+)A/T shift indicator light (N)Continuity
F1 (±) ± F12 (+)A/T shift indicator light (D)Continuity
G1 (+) ± G5 (±)Left turn signal indicator lightContinuity
G6 (+) ± G5 (±)Right turn signal indicator lightContinuity
If circuit is not as specified, replace the bulb or circuit plate.
3. INSPECT COMBINATION METER CIRCUIT PLATE
From combination meter ECU to gauges:
TerminalResistance (W)
O1 ± O3
(Engine coolant temperature receiver gauge)Approx. 164.2
O2 ± O4
(Engine coolant temperature receiver gauge)Approx. 151.8
P1 ± P4 (Tachometer)Approx. 164.2
P2 ± P3 (Tachometer)Approx. 151.8
Q1 ± Q4 (Speedometer)Approx. 164.2
Q2 ± Q3 (Speedometer)Approx. 151.8
R1 ± R4 (Fuel receiver gauge)Approx. 164.2
R2 ± R3 (Fuel receiver gauge)Approx. 151.8
If circuit is not as specified, inspect the gauge or meter.
Then recheck system.
If circuit is not as specified, replace the circuit plate.

I04081
Connector ºGº
Connector ºUº
I04082
± BODY ELECTRICALCOMBINATION METER
BE±95
2396 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
4. INSPECT COMBINATION METER CIRCUIT PLATE
From combination meter ECU to telltale light assem-
bly:
Disconnect connector ºGº and ºUº from the meter circuit plate
and inspect the connectors on the wire harness side as follows.
Tester connectionSpecified condition
G1 ± U9Continuity
G3 ± U1Continuity
G5 ± U10Continuity
G6 ± U4Continuity
G7 ± U3Continuity
G8 ± U8Continuity
If circuit is not as specified, replace the circuit plate.
5. INSPECT TELLTALE LIGHT ASSEMBLY CONTINUITY
Switch positionTester connectionCondition
ODO/ TRIP switch Free3 ± 10No continuity
ODO/ TRIP switch
Pushed in3 ± 10Continuity
RESET switch Free8 ± 10No continuity
RESET switch Pushed in8 ± 10Continuity
Turn signal switch RIGHT4 ± 10Continuity
Turn signal switch LEFT9 ± 10Continuity
If continuity is not as specified, replace the telltale light assem-
bly.

I04084
A
D
CB BE±96
± BODY ELECTRICALCOMBINATION METER
2397 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
6. INSPECT SPEEDOMETER ON±VEHICLE
Using a speedometer tester, inspect the speedometer for allow-
able indication error and check the operation of the odometer.
HINT:
Tire wear and tire over or under inflation will increase the indica-
tion error.
USA (mph)CANADA (km/h)
Standard indication Allowable range Standard indication Allowable range
20 18 ± 24 20 17 ± 24
40 38 ± 44 40 38 ± 46
60 56 ± 66 60 57.5 ± 67
80 78 ± 88 80 77 ± 88
100 98 ± 110 100 96 ± 109
120 118 ± 132 120 115 ± 130
140 134 ± 151.5
160 153 ± 173
If error is excessive, replace the speedometer.
7. INSPECT SPEEDOMETER RESISTANCE
Measure the resistance between terminals with fixing pointer to
the stopper.
Tester connectionResistance (W)
A ± B140 ± 185
C ± D130 ± 175
If resistance value is not as the specified, replace the meter.
8. INSPECT TACHOMETER/
ON±VEHICLE
(a) Connect a tune±up test tachometer, and start the engine.
NOTICE:

Reversing the connection of the tachometer will dam-
age the transistors and diodes inside.

When removing or installing the tachometer, be care-
ful not to drop or subject it to heavy shocks.
(b) Compare the tester and tachometer indications.
DC 13.5 V 25 °C at (77°F)
Standard indicationAllowable range
700630 ± 770
1,000900 ± 1,100
2,0001,850 ± 2,150
3,0002,800 ± 3,200
4,0003,800 ± 4,200
5,0004,800 ± 5,200
6,0005,750 ± 6,250
7,0006,700 ± 7,300

I04085
AD
C
B
I04086
Fuel Receiver Gauge
Battery Ignition
Switch
Main
Sender
Gauge Wire Harness
Side
I04087
Battery Ignition
SwitchFuel Receiver Gauge
Wire Harness
SideSub
Sender
Gauge12
I04089
AD
C
B
I04090
F
1/2
E32
± BODY ELECTRICALCOMBINATION METER
BE±97
2398 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
9. INSPECT TACHOMETER RESISTANCE
Measure the resistance between terminals with fixing pointer to
the stopper.
Tester connectionResistance (W)
A ± B140 ± 185
C ± D130 ± 175
If resistance value is not as specified, replace the meter.
10. INSPECT FUEL RECEIVER GAUGE OPERATION
(See page DI±752)
(a) Disconnect the connector from the main sender gauge.
(b) Turn the ignition switch ON, check that the receiver gauge
needle indicates EMPTY.
(c) Connect the main sender gauge.
(d) Disconnect the connector from the sub sender gauge.
(e) Turn the ignition switch ON, check that the receiver gauge
needle indicates EMPTY.
HINT:
Because of the silicon oil in the gauge, it will take a short time
for needle to stabilize.
If operation is not as specified, inspect the receiver gauge resis-
tance.
11. INSPECT FUEL RECEIVER GAUGE RESISTANCE
Measure the resistance between terminals with fixing pointer to
the stopper.
Tester connectionResistance (W)
A ± B140 ± 185
C ± D130 ± 175
If resistance value is not as specified, replace the receiver
gauge.
12. INSPECT FUEL MAIN SENDER GAUGE RESISTANCE
Measure the resistance between terminals 1 and 2 for each
float position.
Float position mm (in.)Resistance (W)
F: Approx. 34.6 (1.36) ± 3 (0.12)Approx. 2.0 ± 1.0
1/2: Approx. 52.4 (2.06) ± 3 (0.12)Approx. 26.1 ± 3.0
E: Approx. 134.9 (5.31) ± 3 (0.12)Approx. 48.7 ± 1.0
If resistance value is not as specified, replace the main sender
gauge.

I04091
F
E1
2
1/2
I04094
A
D
C
B
I01277
Battery Ignition
SwitchWarning Light
Wire Harness Side
1 BE±98
± BODY ELECTRICALCOMBINATION METER
2399 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
13. INSPECT FUEL SUB SENDER GAUGE RESISTANCE
Measure the resistance between terminals 1 and 2 for each
float position.
Float position mm (in.)Resistance (W)
F: Approx. 9.5 (0.37) ± 3 (0.12)Approx. 2.0 ± 1.0
1/2: Approx. 110.5 (4.35) ± 3 (0.12)Approx. 33.0 ± 3.0
E: Approx. 206.5 (8.13) ± 3 (0.12)Approx. 61.3 ± 1.0
If resistance value is not as specified, replace the sub sender
gauge.
14. INSPECT ENGINE COOLANT TEMPERATURE RE-
CEIVER GAUGE OPERATION (See page DI±754)
15. INSPECT ENGINE COOLANT TEMPERATURE RE-
CEIVER GAUGE RESISTANCE
Measure the resistance between terminals with fixing pointer to
the stopper.
Tester connectionResistance (W)
A ± B140 ± 185
C ± D130 ± 175
If resistance value is not as specified, replace the receiver
gauge.
HINT:
This circuit includes the diode.
If resistance value is not as specified, replace the receiver
gauge.
16. INSPECT LOW OIL PRESSURE WARNING LIGHT
(a) Disconnect the connector from the warning switch and
ground terminal on the wire harness side connector.
(b) Turn the ignition switch ON and check that the warning
light lights up.
If the warning light does not light up, test the bulb.

I01278
I01279
Battery Ignition
SwitchWarning Light
I04095
OFF
ON
I04096
± BODY ELECTRICALCOMBINATION METER
BE±99
2400 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
17. INSPECT LOW OIL PRESSURE SWITCH CONTINUITY
(a) Disconnect the connector from the switch.
(b) Check that continuity exists between terminal and ground
with the engine stopped.
(c) Check that no continuity exists between terminal and
ground with the engine running.
HINT:
Oil pressure should be over 24.5 kPa (0.25 kgf/cm
2, 3.55 psi).
If operation is not as specified, replace the switch.
18. INSPECT BRAKE WARNING LIGHT
(a) Disconnect the connector from the brake fluid warning
switch.
(b) Release the parking brake pedal.
(c) Connect the terminals on the wire harness side of the lev-
el warning switch connector.
(d) Start the engine, check that the warning light lights up.
If the warning light does not light up, test the bulb or wire har-
ness.
19. INSPECT BRAKE FLUID LEVEL WARNING SWITCH
CONTINUITY
(a) Remove the reservoir tank cap and strainer.
(b) Disconnect the connector.
(c) Check that no continuity exists between the terminals with
the switch OFF (float up).
(d) Use siphon, etc. to take fluid out of the reservoir tank.
(e) Check that continuity exists between the terminals with
the switch ON (float down)
(f) Pour the fluid back in the reservoir tank.
If operation is not as specified, replace the switch.
20. INSPECT BRAKE FLUID LEVEL WARNING SWITCH
CIRCUIT (See page DI±835)
21. INSPECT PARKING BRAKE SWITCH CONTINUITY
(a) Check that continuity exists between the terminal and
switch body with the switch ON (switch pin released).
(b) Check that no continuity exists between the terminal and
switch body with the switch OFF (switch pin pushed in).
If operation is not as specified, replace the switch or inspect
ground point.
22. INSPECT PARKING BRAKE SWITCH CIRCUIT
(See page DI±796)

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.

I04102
ON OFF
I04103
ON OFF
I04104
Wire Harness Side
I01286
BatteryWarning Light
± BODY ELECTRICALCOMBINATION METER
BE±101
2402 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
26. INSPECT ENGINE OIL LEVEL WARNING SENSOR
(a) Check that continuity exists between terminals with the
switch to below 40 °C (104 °F). (Warning switch ON)
(b) Heat the switch to above 60 °C (140 °F) in an oil bath.
(c) Check that there is continuity between terminals with the
switch ON (float up).
(d) Check that there is no continuity between terminals with
the switch OFF (float down).
If operation is not as specified, replace the switch.
27. INSPECT ENGINE OIL LEVEL WARNING SENSOR
CIRCUIT
Disconnect the switch connector and inspect the connector on
wire harness side, as shown.
Tester connectionConditionSpecified condition
2 ± GroundConstantContinuity
If continuity is not as specified, inspect the wire harness or
ground point.
28. INSPECT OPEN DOOR WARNING LIGHT
Disconnect the connector from the door courtesy switch and
ground terminal 1 on the wire harness side, and check that the
warning light lights up.
If the warning light does not light up, inspect the bulb or wire har-
ness.
29. INSPECT DOOR COURTESY SWITCH CONTINUITY
AND CIRCUIT (See page BE±60)