low oil pressure LEXUS GS400 2000 Service Repair Manual

AC2810
AC0W6±01
AC2811
N11084
Wrong Okay
HI LO HILO
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±1
2686 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
AIR CONDITIONING SYSTEM
PRECAUTION
1. DO NOT HANDLE REFRIGERANT IN AN ENCLOSED
AREA OR NEAR AN OPEN FLAME
2. ALWAYS WEAR EYE PROTECTION
3. BE CAREFUL NOT TO GET LIQUID REFRIGERANT IN
YOUR EYES OR ON YOUR SKIN
If liquid refrigerant gets in your eyes or on your skin.
(a) Wash the area with lots of cool water.
CAUTION:
Do not rub your eyes or skin.
(b) Apply clean petroleum jelly to the skin.
(c) Go immediately to a physician or hospital for professional
treatment.
4. NEVER HEAT CONTAINER OR EXPOSE IT TO NAKED
FLAME
5. BE CAREFUL NOT TO DROP CONTAINER AND NOT
TO APPLY PHYSICAL SHOCKS TO IT
6. DO NOT OPERATE COMPRESSOR WITHOUT
ENOUGH REFRIGERANT IN REFRIGERANT SYSTEM
If there is not enough refrigerant in the refrigerant system oil lu-
brication will be insufficient and compressor burnout may occur,
so take care to avoid this, necessary care should be taken.
7. DO NOT OPEN HIGH PRESSURE MANIFOLD VALVE
WHILE COMPRESSOR IS OPERATING
If the high pressure valves opened, refrigerant flows in the re-
verse direction and could cause the charging cylinder to rup-
ture, so open and close the only low pressure valve.
8. BE CAREFUL NOT TO OVERCHARGE SYSTEM WITH
REFRIGERANT
If refrigerant is overcharged, it causes problems such as insuffi-
cient cooling, poor fuel economy, engine overheating etc.

I01390
Condition: Insufficient cooling
I01392
Condition: Insufficient cooling
NOTE : These gauge indica-
tions are shown when the
refrigeration system has
been opened and the refrig-
erant charged without vacu-
um purging.
± AIR CONDITIONINGAIR CONDITIONING SYSTEM
AC±7
2692 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(6) Refrigerant overcharged or insufficient cooling of
condenser
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure too high on both low
and high pressure sides

No air bubbles seen through the
sight glass even when the engine
rpm is lowered
Unable to develop sufficient per-
formance due to excessive refrig-
eration system

Insufficient cooling of condenser
Excessive refrigerant in
cycle " refrigerant over charged

Condenser cooling " condenser
fins clogged of condenser fan
faulty
(1) Clean condenser
(2) Check condenser fan motor
operation
(3) If (1) and (2) are in normal
state, check amount of refrigerant
Charge proper amount of refriger-
ant
(7) Air present in refrigeration system
Symptom seen in
refrigeration systemProbable causeDiagnosisRemedy

Pressure too high on both low
and high pressure sides

The low pressure piping hot to
touch

Bubbles seen in sight glass
Air entered in refrigeration system

Air present in refrigeration sys-
tem

Insufficient vacuum purging
(1) Check compressor oil to see if
it is dirty or insufficient
(2) Evacuate air and charge new
refrigerant

AC0XO±01
I03742
± AIR CONDITIONINGPRESSURE SWITCH
AC±77
2762 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
REMOVAL
1. DISCHARGE REFRIGERANT FROM REFRIGERATION
SYSTEM
HINT:
At the time of installation, please refer to the following item.
Evacuate air from refrigeration system.
Charge system with refrigerant and inspect for leakage of refrig-
erant.
Specified amount: 600 ± 50 g (21.16 ± 1.76 oz.)
2. REMOVE PRESSURE SWITCH FROM LIQUID TUBE
Disconnect the connector and remove the pressure switch.
Torque: 10 N´m (100 kgf´cm, 7 ft´lbf)
HINT:

Lock the switch mount on the tube with an open end
wrench, being careful not to deform the tube, and remove
the switch.

At the time of installation, please refer to the following
item.
Lubricate a new O±ring with compressor oil and install the
switch.

I01360
Fuel Tank

Fuel Main
Sender Gauge
Fuel Tank

Fuel Sub
Sender Gauge
Occupant Detection Sensor
(Passenger seat belt
warning sensor)
Engine Oil Level
Warning Sensor Engine Oil Level
Warning Sensor
Park/ Neutral
Position Switch
Low Oil Pressure
Warning Switch
Park/ Neutral
Position Switch
Low Oil Pressure
Warning Switch
GS300GS400 Light Failure Sensor
± BODY ELECTRICALCOMBINATION METER
BE±81
2382 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

I04253

Meter Circuit Plate ± 2
Combination Meter ECU
SLIP Indicator
TRAC OFF Indicator
Window Washer Level Warning
ABS Warning
VSC Warning
Brake Fluid Level Warning
ECT SNOW Indicator
Low Oil Pressure Warning
ECT PWR Indicator
Discharge Warning
CRUISE MAIN Indicator
Seat Belt Warning
Rear Light Indicator
Headlight Leveling Indicator
SRS Warning
Open Door Warning
Fog Light IndicatorA/T 2 Indicaor
Engine Oil Level Indicator
Malfunction Indicator
Fuel Level Indicator
Headlight Indicator (USA)
Taillight Indicator (CANADA) ODO/
TRIP
Display
PanelIG+
SLIP
TRC OFF
WASHER
ABS
VSC
BRAKE
ECT SNOW
OIL P
ECT PWR
CHARGE
CRUISE
SEAT BELT
Rr LIGHT
HEAD LVL
AIRBAG
SRS +B
DOOR
FR FOG
COM1
SEG30
TEST1
TEST2
TEST3
GroundCHECK
ENG
IG+
FUEL
IG+
BEAM±
BEAM+ SRS +BTAIL A/T R
A/T L
A/T N
A/T D
OIL LVLDIM+
A/T 2
A/T 3
A/T 4F12
A/T PF11
F10
F9
F8
F5
F4
F2
F1
C7
C5
C3
D12
D8 E11
E10
E9
E8
E7
E6
J1
J33
D6
D4Hi±Beam Indicator
D2 E20
E19
E18
E17
E16
E15
E14
E13
E12
E3
E1 E5
E4A/T 3 Indicaor
A/T 4 Indicaor
A/T P Indicaor
A/T R Indicaor
A/T L Indicaor
A/T N Indicaor
A/T D Indicaor
T1
T2
T3
T4
~~
D10 BE±88
± BODY ELECTRICALCOMBINATION METER
2389 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)

I04079
Connector ºCº Connector ºDº
Connector ºFº Connector ºEº
Connector ºGº
1 131 13
1 201 12
± BODY ELECTRICALCOMBINATION METER
BE±93
2394 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
2. INSPECT COMBINATION METER CIRCUIT PLATE
Warning light circuit plate:
(a) Remove meter cover.
(b) Disconnect connectors ºCº, ºDº, ºEº, ºFº and ºGº from the
meter circuit plate and inspect the connectors on the wire
harness side as shown in the table.
Tester connectionCheck indicator lightSpecified condition
D10 (+) ± D12 (±)Fuel level warning lightContinuity
D6 (+) ± D8 (±)Headlight indiactor light (USA)
Taillight indiactor light (CANADA)Continuity
D2 (+) ± D4 (±)Hi±beam indicator lightContinuity
C3 (+) ± C7 (±)Engine oil level warning lightContinuity
C3 (+) ± C5 (±)Malfunction indicator lightContinuity
E19 (±) ± E20 (+)Slip warning lightContinuity
E18 (±) ± E20 (+)TRAC OFF indicator lightContinuity
E17 (±) ± E20 (+)Window washer level warning lightContinuity
E16 (±) ± E20 (+)ABS warning lightContinuity
E15 (±) ± E20 (+)VSC OFF indicator lightContinuity
E14 (±) ± E20 (+)Brake warning lightContinuity
E13 (±) ± E20 (+)ECT SNOW indicator lightContinuity
E12 (±) ± E20 (+)Low oil pressure warning lightContinuity
E11 (±) ± E20 (+)ECT PWR indicator lightContinuity
E10 (±) ± E20 (+)Discharge warning lightContinuity
E9 (±) ± E20 (+)CRUISE MAIN indicator lightContinuity
E8 (±) ± E20 (+)Seat belt warning lightContinuity
E7 (±) ± E20 (+)Rear Lights warning lightContinuity
E6 (±) ± E20 (+)Headlight leveling indiactorContinuity
E4 (+) ± E5 (±)SRS warning lightContinuity
E3 (±) ± E4 (+)Open door warning lightContinuity
F4 (±) ± F12 (+)A/T shift indicator light (L)Continuity
F11 (±) ± F12 (+)A/T shift indicator light (2)Continuity
F10 (±) ± F12 (+)A/T shift indicator light (3)Continuity
F8 (±) ± F12 (+)A/T shift indicator light (P)Continuity

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)

EM0D1±05
A11132
Compression Tester
± ENGINE MECHANICAL (2JZ±GE)COMPRESSION
EM±3
1357 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
COMPRESSION
INSPECTION
HINT:
If there is lack of power, excessive oil consumption or poor fuel
economy, measure the compression pressure.
1. WARM UP AND STOP ENGINE
Allow the engine to warm up to normal operating temperature.
2. REMOVE ENGINE COVER
Remove the 4 nuts and engine cover.
3. DISCONNECT IGNITION COILS AND HIGH±TENSION
CORD SET ASSEMBLY (See page IG±7)
4. REMOVE SPARK PLUGS
5. DISCONNECT INJECTOR CONNECTORS
6. CHECK CYLINDER COMPRESSION
(a) Insert a compression tester into the spark plug hole.
(b) While cranking the engine, measure the compression
pressure.
HINT:
Always use a fully charged battery to obtain engine revolutions
of 250 rpm or more.
(c) Repeat steps (a) through (b) for each cylinder.
NOTICE:
This measurement must be done in as short a time as pos-
sible.
Compression:
1,324 kPa (13.5 kgf/cm
2, 192 psi) or more
Minimum pressure:
1,079 kPa (11.0 kgf/cm
2, 156 psi)
Difference between each cylinder:
98 kPa (1.0 kgf/cm
2, 14 psi) or less
(d) If the cylinder compression in 1 or more cylinders is low,
pour a small amount of engine oil into the cylinder through
the spark plug hole and repeat steps (a) through (b) for
the cylinder with low compression.

If adding oil helps the compression, it is likely that
the piston rings and/or cylinder bore are probably
worn or damaged.

If pressure stays low, a valve may be sticking or
seating improper, or there may be leakage past the
gasket.

EM0DC±03
A02682
A02683
A02705
A02706
P02072
EM±40
± ENGINE MECHANICAL (2JZ±GE)CYLINDER HEAD
1394 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. CLEAN TOP SURFACES OF PISTONS AND
CYLINDER BLOCK
(a) Turn the crankshaft, and bring each piston to top dead
center (TDC). Using a gasket scraper, remove all the car-
bon from the piston top surface.
(b) Using a gasket scraper, remove all the gasket material
from the top surface of the cylinder block.
(c) Using compressed air, blow carbon and oil from the bolt
holes.
CAUTION:
Protect your eyes when using high ± pressure compressed
air.
2. CLEAN CYLINDER HEAD
(a) Remove the gasket material.
Using a gasket scraper, remove all the gasket material
from the cylinder block surface.
NOTICE:
Be careful not to scratch the cylinder block contact sur-
face.
(b) Clean the combustion chambers.
Using a wire brush, remove all the carbon from the com-
bustion chambers.
NOTICE:
Be careful not to scratch the cylinder block contact sur-
face.
(c) Clean the valve guide bushings.
Using a valve guide bushing brush and solvent, clean all
the guide bushings.