ECU LEXUS GS400 2000 Service Owner's Guide

± BODY ELECTRICALWIRELESS DOOR LOCK CONTROL SYSTEM
BE±165
2466 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
MPX body performs LOCK±UNLOCK operation 5 times at a 1 sec.
interval to inform the operator that prohibition mode has been selected.
Press again either one of 3 switches on the transmitter for more than 1 sec.
MPX body ECU automatically performs LOCK±UNLOCK operation once or
twice at a 1 sec. interval to inform the operator that the receiver has received the
signal from the transmitter.
LOCK±UNLOCK occurs once
LOCK±UNLOCK occurs twice Registration of recognition code is completed
Registration of recognition code has not been completed.

Recognition code received first time and second time did not match.
Proceed to continue registration
If even one of the following conditions is satisfied, registration of recognition
codes is completed.

40 secs. elapses since the MPX body ECU response.

The driver's door is closed.

The key plate is inserted in the ignition key cylinder.

4 type recognition codes are registration at one time.
Registration of recognition codes (add mode or rewrite mode) is completed.
Within
3 secs.Within
40 secs.
ON
LOCK
Approx.
1 sec.Approx.
1 sec.
When prohibition
mode is selected.
Press the lock and unlock switches on the transmitter simultaneously within 1 sec.
If LOCK±UNLOCK operation can not be performed at all, the mode returns to the
normal mode, then start with ºStart registration of recognition codeº.
Proceed to finish registration
Within 40 secs.

BE02J±10
I01368
Mirror Assembly

Mirror Motor
Mirror Switch

Left/Right Adjustment Switch

Mirror Control SwitchIgnition Switch
Driver Side Junction Block

Body ECU No.2
± BODY ELECTRICALPOWER MIRROR CONTROL SYSTEM
BE±175
2476 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
POWER MIRROR CONTROL SYSTEM
LOCATION

BE0HC±06
I01369
Electro Chromic Outer Mirror
Electro Chromic Inner Mirror
Driver Side Junction Block

ECU±IG Fuse
± BODY ELECTRICALELECTRO CHROMIC MIRROR SYSTEM
BE±181
2482 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
ELECTRO CHROMIC MIRROR SYSTEM
LOCATION

BE10X±03
I10058
Radio Receiver Assembly Power Amplifier CD Auto Changer BE±190
± BODY ELECTRICALAUDIO SYSTEM
2491 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
AUDIO SYSTEM
DESCRIPTION
1. OUTLINE OF AVC±LAN
(a) What is AVC±LAN?
AVC±LAN is the abbreviation, which stands for Audio Visual Communication±Local Area Network.
This is a unified standard co±developed by 6 audio manufactures associated with Toyota Motor Corpo-
ration.
The Unified standard covers signals, such as audio signal, visual signal, signal for switch indication
and communication signal.
(b) Objectives
Recently the car audio system has been rapidly developed and functions have been changed drasti-
cally. The conventional system has been switched to the multi±media type such as a navigation sys-
tem. At the same time the level of customers needs to audio system has been upgraded. This lies be-
hind this standardization.
The concrete objectives are explained below.
(1) When products by different manufactures were combined together, there used to be a case that
malfunction occurred such as sound did not come out. This problem has been resolved by stan-
dardization of signals.
(2) Various types of after market products have been able to add or replace freely.
(3) Because of the above (2), each manufacture has become able to concentrate on developing
products in their strongest field. This has enabled many types of products provided inexpensive-
ly.
(4) Conventionally, a new product developed by a manufacture could not be used due to a lack of
compatibility with other manufactures products. Because of this new standard, users can enjoy
compatible products provided for them timely.
The above descriptions are the objectives to introduce AVC±LAN. By this standardization, development of
new products will no longer cause systematic errors. Thus, this is very effective standard for a product in the
future.
HINT:
When +B short or GND short is detected in AVC±LAN circuit, communication stops. Accordingly the
audio system does not function normally.
When audio system is not equipped with a navigation system, audio head unit is the master unit. (When
audio system is equipped with a navigation system, navigation ECU is the master unit.)
The car audio system using AVC±LAN circuit has a diagnosis function.
Each product has its own specified numbers called physical address. Numbers are also allotted to
each function in one product, which are called logical address.

BE±22
± BODY ELECTRICALPOWER SOURCE
2323 Author: Date:
2000 LEXUS GS300/GS400 (RM718U) ECU±B1 30 ± Ground
ConstantBattery positive voltage
HTR 31 ± GroundConstantBattery positive voltage
FAN MAIN 33 ± GroundConstantBattery positive voltage
CDS FAN 35 ± GroundIgnition switch ONBattery positive voltage
RAD FAN 35 ± GroundIgnition switch ONBattery positive voltage
H±LP R LWR 38 ± GroundLight control switch HEADBattery positive voltage
H±LP L LWR 38 ± GroundLight control switch HEADBattery positive voltage
H±LP R UPR 38 ± GroundLight control switch HEADBattery positive voltage
H±LP L UPR 42 ± GroundLight control switch HEADBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
(b) Remove the relay from the junction block and inspect the
connector on junction block side.
Relay Tester connectionConditionSpecified condition
H±LP 44 ± GroundConstantBattery positive voltage
H±LP 46 ± GroundConstantBattery positive voltage
ST 48 ± GroundConstantContinuity
ST 51 ± GroundConstantBattery positive voltage
EFI MAIN 53 ± GroundConstantContinuity
EFI MAIN 55 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

BE±26
± BODY ELECTRICALPOWER SOURCE
2327 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(a) Remove the fuse from the junction block and inspect the
connector on junction block side.
Fuse Tester connectionConditionSpecified condition
AM1 1 ± GroundConstantBattery positive voltage
WASHER 3 ± GroundIgnition switch ONBattery positive voltage
FOG 5 ± GroundConstantBattery positive voltage
TAIL 7 ± GroundLight control switch TAIL or HEADBattery positive voltage
SRS±ACC 9 ± GroundIgnition switch ACC or ONBattery positive voltage
GAUGE 11 ± GroundIgnition switch ONBattery positive voltage
FUEL OPN 13 ± GroundConstantBattery positive voltage
D FR DOOR 15 ± GroundConstantBattery positive voltage
PANEL 17 ± GroundLight control switch TAIL or HEADBattery positive voltage
HTR 19 ± GroundIgnition switch ONBattery positive voltage
SRS±B 21 ± GroundConstantBattery positive voltage
P/SEAT (D) 23 ± GroundConstantBattery positive voltage
RAD NO.2 25 ± GroundIgnition switch ACC or ONBattery positive voltage
WIP 27 ± GroundIgnition switch ONBattery positive voltage
OBD 29 ± GroundConstantBattery positive voltage
STOP 31 ± GroundConstantBattery positive voltage
CIG 33 ± GroundIgnition switch ACC or ONBattery positive voltage
ECU±IG 35 ± GroundIgnition switch ONBattery positive voltage
ST 37 ± GroundIgnition switch ONBattery positive voltage
IGN 39 ± GroundIgnition switch ONBattery positive voltage
D RR DOOR 41 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
(b) Remove the relay from the junction block and inspect the
connector on junction block side.
Relay Tester connectionConditionSpecified condition
Fog light 43 ± GroundConstantBattery positive voltage
Fog light 44 ± GroundConstantContinuity
Fog light 46 ± GroundLight control switch HEADBattery positive voltage
Taillight 47 ± GroundConstantBattery positive voltage
Taillight 48 ± GroundConstantContinuity
Taillight 50 ± GroundConstantContinuity
If the circuit is not as specified, inspect the circuits connected
to other parts.

BE±28
± BODY ELECTRICALPOWER SOURCE
2329 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
(a) Remove the fuse from the junction block and inspect the
connector on junction block side.
Fuse Tester connectionConditionSpecified condition
DEF 1 ± GroundConstantBattery positive voltage
MIR HTR 7 ± GroundIgnition switch ONBattery positive voltage
S/ROOF 13 ± GroundConstantBattery positive voltage
P FR DOOR 15 ± GroundConstantBattery positive voltage
P/SEAT (P) 23 ± GroundConstantBattery positive voltage
DOME 25 ± GroundConstantBattery positive voltage
S±HTR 27 ± GroundIgnition switch ONBattery positive voltage
TV 31 ± GroundConstantBattery positive voltage
ECU±B2 33 ± GroundConstantBattery positive voltage
P FR DOOR 41 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.
(b) Remove the relay from the junction block and inspect the
connector on junction block side.
Relay Tester connectionConditionSpecified condition
Ignition Main 43 ± GroundIgnition switch ONBattery positive voltage
Mirror Heater 47 ± GroundIgnition switch ONBattery positive voltage
Mirror Heater 50 ± GroundConstantBattery positive voltage
If the circuit is not as specified, inspect the circuits connected
to other parts.

BE0GD±10
I01372
Ignition SwitchRadio Assembly Tweeter
Front Speakers
Rear Speakers
Tweeter
Radio Assembly LEXUS Navigatioin
System Woofer
Power Amplifier
(NAKAMICHI made)
Driver Side Junction Block

RAD NO.2 FuseEngine Room No.1
Junction Block

ECU±B1 Fuse

RAD NO.1 Fuse
Passenger Side
Junction Block

DOME Fuse CD Auto ChangerCD Magazine
Power Amplifier
(PIONEER made)
BE±216
± BODY ELECTRICALAUDIO SYSTEM
2517 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
LOCATION
The vehicle shown in this illustration is ºGS400º.
All components of ºGS300º other than the ones used for engine are same as ºGS400º.

BE0G0±05
1
CLOCK WILL NOT OPERATEPASSENGER SEAT BELT WARNING LIGHT DOES NOT OPERATE
I04264
Wire Harness Side5
4
3
6
1RAD NO.2 Fuse
DOME Fuse
Combination
Meter
Body ECU
No.2
Ground ACC
+B
PBEW
ILL
E Clock Assembly
± BODY ELECTRICALCLOCK
BE±227
2528 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
CLOCK
TROUBLESHOOTING
HINT:
Troubleshoot the clock according to the table below.
TroubleshootingNo.
Passenger seat belt warning light does not light up.1
Clock will not operate1
Clock loses or gains time2
± 1.5 seconds / day
INSPECT CLOCK CIRCUIT
(See page DI±849)
TROUBLESHOOTING NO.1
(a) Check that the battery positive voltage is 10 ± 16 V.
If voltage is not as specified, replace the battery.
(b) Check that the DOME and RAD NO.2 fuses are not
blown.
If the fuse is blown, replace the fuse and check for short.
(c) Troubleshoot the clock as follows.
HINT:
Inspect the connector on the wire harness side.

Ye s
Ye sNo
No
Is there battery positive voltage between terminal +B and
body ground?
Is there battery positive voltage between terminal ACC and
body ground?
Replace clock.+B wire harness faulty.
Ye sNo
Is there continuity between terminal GND and
body ground?Ground wire harnss faulty. ACC wire harness faulty.
2 CLOCK LOSES OR GAINS TIME
I04264
Wire Harness Side5
4
3
6
1RAD NO.2 Fuse
DOME Fuse
Combination
Meter
Body ECU
No.2
Ground ACC
+B
PBEW
ILL
E Clock Assembly
Ye s
Is there battery positive voltage between terminal +B and
body ground?
Adjust or replace clock.Bellow 10 V
Locate cause and repair, or recharge battery.
Ye s
Is there battery positive voltage between terminal ACC and
body ground?Bellow 10 V
Locate cause and repair, or recharge battery.
BE±228
± BODY ELECTRICALCLOCK
2529 Author: Date:
2000 LEXUS GS300/GS400 (RM718U)
TROUBLESHOOTING NO.2
(a) Check that the battery positive voltage is 10 ± 16 V.
If voltage is not as specified, replace the battery.
(b) Inspect the error of the clock.
Allowable error (per day): ± 1.5 seconds
If the error exceeds the allowable error, replace the clock.
(c) Check that the clock adjusting button is sticking in posi-
tion and has failed to return.
If the error exceeds the allowable error, replace the clock.
(d) Troubleshoot the clock as follows.
HINT:
Inspect the connector on the wire harness side.