2000 LEXUS GS400 ECU

BE01I±09
± BODY ELECTRICALBODY ELECTRICAL SYSTEM
BE±1
2302 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
BODY ELECTRICAL SYSTEM
PRECAUTION
HINT:
Take care to observe the following precautions when performing inspections or removal and replacement
of body electrical related parts.
1. HEADLIGHT SYSTEM

Halogen bulbs have pressurized gas inside and require special handling. They can burst if scratched
or dropped. Hold a bulb only by its plastic or metal case. Don't touch the glass part of a bulb with bare
hands.

When high voltage socket of discharge headlight is touched with the light control switch HEAD, high
voltage of 20,000 V is momentarily generated. This might lead to a serious accident.

Never connect the tester to the high voltage socket of discharge headlight for measurement, as this
leads to a serious accident because of high voltage.

When performing operation related to the discharge headlight, make sure to do it in the place with no
water of rain to prevent electric shock, with light control switch OFF, battery terminal removed, connec-
tor of light control ECU disconnected.

When performing operation related to the discharge headlight, make sure to do it after assembling has
been completely over and never light up without a bulb installed.

Do not light up the discharge headlight using another power source except vehicle's.

When there is a defect on the discharge headlight or any shock has been applied to it, replace the light
with a new one.
Even if the light operates normally, there is a possibility that the fail±safe function works.
2. SRS (SUPPLEMENTAL RESTRAINT SYSTEM)
The LEXUS GS300/ 400 is equipped with an SRS (Supplemental Restraint System) such as the driver airbag
and front passenger airbag. Failure to carry out service operation in the correct sequence could cause the
SRS to unexpectedly deploy during servicing, possibly leading to a serious accident. Before servicing (in-
cluding removal or installation of parts, inspection or replacement), be sure to read the precautionary notices
in the RS section.
3. COMBINATION METER SYSTEM
The cold cathode tube connectors (Connector ºKºand ºLº) in the combination meter are charged with high
voltage AC current when power is supplied, so do not touch them when they are charged.

BE0GU±05
I01361
Ignition Switch
Buckle Switch
Driver Side Junction Block

ECU±IG Fuse
Electric Tension Reducer Solenoid
BE±104
± BODY ELECTRICALELECTRIC TENSION REDUCER SYSTEM
2405 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ELECTRIC TENSION REDUCER SYSTEM
LOCATION

BE0GT±03
I04112
6
I04113
I04114
Wire Harness Side
Connector ºAº Connector ºBº
I01200
2 1
35
2 5
1 3
BE±108
± BODY ELECTRICALDEFOGGER SYSTEM
2409 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
INSPECTION
1. INSPECT DEFOGGER TIMER OPERATION
(a) Connect the positive (+) lead from the voltmeter to termi-
nal 6 of body ECU No.1 connector and negative (±) lead
to body ground.
(b) When the switch is OFF, the voltage should be approx.
12V.
(c) Turn the defogger switch ON and check that the indicator
lights up and that the voltage is less than 1 V.
(d) After 15 minutes, check that the switch is OFF and the
voltage is approx. 12 V.
If operation is not as specified, replace the switch.
2. INSPECT DEFOGGER SWITCH (in PANEL SWITCH)
CIRCUIT
Connector disconnected:
Disconnect the connector from the panel switch and inspect the
connector on wire harness side, as shown in the chart.
Tester connectionConditionSpecified condition
B10 ± GroundConstantContinuity
A1 ± GroundConstantBattery voltage
A2 ± GroundIgnition switch LOCKNo voltage
A2 ± GroundIgnition switch ACC or ONBattery voltage
If the circuit is not as specified, replace the switch.
3. INSPECT DEFOGGER RELAY CONTINUITY
ConditionTester connectionSpecified condition
Constant1 ± 2Continuity
Apply B+ between
terminals 1 and 2.3 ± 5Continuity
If continuity is not as specified, replace the relay.
4. INSPECT DEFOGGER RELAY CIRCUIT
(See page DI±812 and BE±21)

BE02C±02
± BODY ELECTRICALPOWER WINDOW CONTROL SYSTEM
BE±111
2412 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
POWER WINDOW CONTROL SYSTEM
TROUBLESHOOTING
1. WINDOW DOES NOT OPERATE WITH POWER WINDOW MASTER SWITCH. (MANUAL OR AU-
TOMATIC OPERATION CAN NOT BE PERFORMED.)
TroubleSuspect Area (terminal No.)Parts name
All windows do not operate with master
switch of each window.
PWS terminal of body ECU does not output sig-
nal.

Body ECU PWS terminal (B8) output

Master Switch PW terminal (15) output

Check wire harness between PWS terminal
and PW terminal (15)

Body ECU

Master switch
Windows except driver's do not operate
with master switch of each window.
Master switch (window lock circuit) faulty

Check continuity between master switch PW
terminal (15) and W/L2 terminal (10)

Check wire harness between W/L2 terminal of
master switch (10) and PCT terminals of each
power window switch.

Master switch
Only specific window does not operate.
(Manual and automatic operation can not
be performed.)
FLOW CHART ±
Only specific window does not operate.
(Automatic operation can not be per-
formed.)When ºJam Protectionº sensor is defective, auto-
matic function as a fail±safe function might be
unable.
Master switch

Power window switch

Door control ECU

Only specific window does not operate. (Neither manual nor automatic operation is available.)1
Diagnosis check:
Check output diagnosis trouble codes 21 ± 26 when operating the
master switch and power window switch.
(Refer to ºMultiplex Communication Systemº)If the door lock of the applicable seat operates.
Wire harness faulty or
D FR DOOR fuse faulty.
No Yes
Disconnect the driver door control ECU connector.
Ye sNo
Voltage check:
With ignition switch ON if 10 to 14 V power is
supplied to PCT (3) of power window switch.Wire harness faulty.
(Between master switch W/L2 terminal
(10) and power window switch PCT
terminal (3)
Continuity check:
Master switch faulty.
Check continuity master switch and power window switch.No (Driver side)
No (Except driver side)Ye s
No Ye s
Wire harness check:
Master switch
Master switch Driver door control ECU
AUTO (7)
DDN (18)
DUP (6)AUTO (B6)
MDN (B4)
MUP (B5)
Power window switch
Power window switch Driver door control ECU
A (5)
D (4)
U (6)AUTO (A22)
MDN (A23)
MUP (A24)
Wire harness faulty.
Continuity check:
Check continuity between UP terminal (A2) and
GND terminal (C12), DN terminal (A11) and
GND terminal (C12) of driver door control ECU .
Ye s
When replacing with the normal driver door control ECU
removed from another seat, if it operates normally.
Driver door control ECU faulty.No Yes
Driver door control ECU faulty.
No
Power window motor check:
Disconnect the motor connector.
Connect the battery positive (+) lead to terminal
UP (2) and negative (±) lead to terminal DN
(1) of wire harness side motor connector, check that
the motor operates.
Check power window motor.Ye s
No
Wire harness faulty.
Ye s
Power window motor faulty.
No
BE±112
± BODY ELECTRICALPOWER WINDOW CONTROL SYSTEM
2413 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
FLOW CHART

± BODY ELECTRICALPOWER WINDOW CONTROL SYSTEM
BE±113
2414 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
2. REMOTE CONTROL OF ALL WINDOWS (EXCEPT DRIVER'S) DOES NOT FUNCTION WITH MAS-
TER SWITCH. (WINDOWS OPERATE NORMALLY WITH EACH OF MASTER SWITCHES.
TroubleSuspect Area (terminal No.)Parts name
All windows (except driver's) do not oper-
ate by remote control.
Fail±safe mode caused by leaving the master
switch ON or short circuit occurred in remote
control control switch of master switch.

Check continuity of master switch.

Master switch
Only passenger's door does not operate.
(UP, DOWN and AUTO DOWN do not op-
erate.)
Driver door control ECU DT1 terminal does not
output.

Driver door control ECU DT1 terminal (B3)

Master switch DT1 terminal (3)

Check wire harness between terminal DT1 (B3)
and DT1 (3)

Driver door control ECU

Master switch
Only passenger's door does not operate.
(Each operation does not operate.)Master switch faulty

Check continuity of master switch.
Only rear right side door does not operate.
(UP, DOWN and AUTO DOWN do not op-
erate.)
Driver door control ECU DT2 terminal does not
output.

Driver door control ECU DT2 terminal (B2)

Master switch DT2 terminal (11)

Check wire harness between terminal DT2 (B2)
and DT2 (11)

Driver door control ECU

Master switch
Only rear right side door does not operate.
(Either UP, DOWN or AUTO DOWN does
not operate.)Master switch faulty

Check continuity of master switch.
Only rear left side door does not operate.
(UP, DOWN and AUTO DOWN do not op-
erate.)
Driver door control ECU DT3 terminal does not
output.

Driver door control ECU DT3 terminal (B1)

Master switch DT3 terminal (14)

Check wire harness between terminal DT3 (B1)
and DT3 (14)

Driver door control ECU

Master switch
Only rear left side door does not operate.
(Either UP, DOWN or AUTO DOWN does
not operate.)Master switch faulty

Check continuity of master switch.
Driver door control ECU

Master switch
Only UP operation does not operate.
(All window (Except driver side) doors.)
Master switch ON SC2 terminal does not output.
Driver door control ECU SC2 terminal does not
input.

Master switch SC2 terminal (12)

Driver door control ECU SC2 terminal (B10)

Check wire harness between terminal SC2 (12)
and SC2 (B10)

Driver door control ECU

Master switch
Only UP operation does not operate.
(Only specific window does not operate.)Master switch faulty

Check continuity of master switch.
Only DOWN operation does not operate.
(All window (Except driver side) doors.)
Master switch ON SC1 terminal does not output.
Driver door control ECU SC1 terminal does not
input.

Master switch SC1 terminal (4)

Driver door control ECU SC1 terminal (B9)

Check wire harness between terminal SC1 (4)
and SC1 (B9)

Driver door control ECU

Master switch
Only DOWN operation does not operate.
(Only specific window does not operate.)Master switch faulty

Check continuity of master switch.

BE±114
± BODY ELECTRICALPOWER WINDOW CONTROL SYSTEM
2415 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) Only AUTO DOWN operation does not
operate.
(All window (Except driver side) doors.)
Master switch ON SC3 terminal does not output.
Driver door control ECU SC3 terminal does not
input.

Master switch SC3 terminal (13)

Driver door control ECU SC3 terminal (B11)

Check wire harness between terminal SC3 (13)
and SC3 (B11)

Driver door control ECU

Master switch
Only AUTO DOWN operation does not
operate.
(Only specific window does not operate.)Master switch faulty

Check continuity of master switch.
3. THE KEY RELATED POWER WINDOW OPERATION DOES NOT OPERATE WITH DRIVER SIDE
DOOR KEY CYLINDER. (MASTER SWITCH OPERATION IS NORMAL.)
TroubleSuspect Area (terminal No.)Parts name
Door lock system does not operate with
door key.Refer to ºPOWER DOOR LOCK CONTROL
SYSTEMº.±
Door lock system does not operate with
door key.
Fail±safe mode caused by error on jam protec-
tion sensor of power window.
(Operation of power window with multi±function
transmitter is prohibited.)
HINT: DTC 31 ± 38 output
Refer to ºMultiplex Communication Systemº.
4. POWER WINDOW DOES NOT OPERATE WITH MULTI±FUNCTION TRANSMITTER. (WINDOWS
OPERATE NORMALLY WITH MASTER SWITCH.)
TroubleSuspect Area (terminal No.)Parts name
Door lock and luggage compartment
opener do not operate with multi±function
transmitter.Refer to ºWIRELESS DOOR LOCK CONTROL
SYSTEMº.±
Only luggage compartment opener oper-
ates with multi±function transmitter.Wireless door lock transmitter faulty.Check wireless door lock transmitter.
Door lock and luggage compartment
opener operate with multi±function trans-
mitter.
Fail±safe mode caused by error on jam protec-
tion sensor of power window.
(Operation of power window with multi±function
transmitter is prohibited.)
HINT: DTC 31 ± 38 output
Refer to ºMultiplex Communication Systemº.
5. WINDOW MOVES DOWN WITHOUT BEING ORDERED DURING THE UP OPERATION
TroubleSuspect Area (terminal No.)Parts name
After the window is fully closed, it starts to
move down.
Power window motor limit switch wire harness
faulty.

Power window motor reset switch is reset.

Driver door control ECU LMT terminal (B12)

Driver door control ECU
The window moves down during the up
operation.FLOW CHART ±