
GENERAL DESCRIPTION
SIMPLIFIED WIRING SYSTEM (SWS)54B-3
SEAT BELT TONE ALARM FUNCTION
If any of the following conditions is met with the igni-
tion switch at "ON" or "ST", the ETACS-ECU sounds 
the tone alarm by using the driver's seat belt switch 
signal and the vehicle speed signal sent from the 
combination meter.
Sounds the tone alarm for six seconds when the 
ignition switch is turned "ON" with the seat belt 
switch on (the driver's seat belt is not fastened). 
This is called "Timer function".
Sounds the tone alarm 12 cycles (after 0.5 sec-
onds) if any of the following conditions is met 
when sixty seconds or more have elapsed since 
the ignition switch is turned "ON". One cycle con-
sists of five-seconds "on" and then three-seconds 
"off".
a. The vehicle speed has reached 8 km/h (5 
mph) while the seat belt switch is turned on 
(driver's seat belt is not fastened) with the 
ignition switch "ON.
b. The seat belt switch has been turned on 
(driver's seat belt has not been fastened) for 
at least ten seconds while the ignition switch 
has been turned "ON" and the vehicle speed 
has been 8 km/h or more.
NOTE: Once the tone alarm has sounded 12 
cycles, it does not sound again until the vehi-
cle speed reduces to 3 km/h (2 mph) or less 
even if any of the following conditions is met.
The tone alarm stops sounding if the ignition 
switch or the seat belt switch is turned off (the 
driver's seat belt is fastened) while the timer 
operation is active. 
.
DOOR AJAR WARNING BUZZER
The buzzer is sounded 4 times by the ETACS-ECU 
to warn the driver if any door is open when the igni-
tion is switched ON and the vehicle speed reaches 8 
km/h or faster. The buzzer will continue to sound for 
4 times even if the ignition, door status, or vehicle 
speed requirements are not maintained.
.
MULTI CENTER DISPLAY OPERATION 
TONE 
The ETACS-ECU sounds the buzzer when the 
buzzer signal is sent from the multi center display.
.
TURN-SIGNAL LAMP BUZZER
The ETACS-ECU sounds the buzzer in sync with the 
turn-signal lamps or hazard warning lamps.
CENTRAL DOOR LOCKING SYSTEM
.
CENTRAL DOOR LOCKING SYSTEM 
OPERATION
Door unlocking by operating the driver’s door lock 
key cylinder:
When the ignition key is inserted in the driver’s 
door lock key cylinder and turned clockwise to 
unlock the driver’s door, the ETACS-ECU oper-
ates its door unlock relay and passes a current 
through the door lock actuator of the driver’s door 
for 0.25 seconds to unlock only the driver’s door.
When the ignition key is turned clockwise again, 
the ETACS-ECU operates its door unlock relay 
and passes a current through the door lock actu-
ators of all doors for 0.25 seconds and to unlock 
all doors.
Door locking or unlocking by operating the driver’s or 
front passenger’s door lock switch:
When the door is locked by the driver’s or front 
passenger’s door lock switch, the ETACS-ECU 
operates its door lock relay and passes a current 
through the door lock actuators of all doors for 
0.25 seconds to lock all doors.
When the door is unlocked by the driver’s or front 
passenger's door lock switch, the ETACS-ECU 
operates its door unlock relay and passes a cur-
rent through the door lock actuators of all doors 
for 0.25 seconds to unlock all doors.
When the door is locked and unlocked by driver’s 
or front passenger's door lock switch consecu-
tively, the ETACS-ECU operates its door lock 
relay and passes a current through the door lock 
actuators of all doors for 0.25 seconds to lock all 
doors. Then, the ETACS-ECU operates its door 
unlock relay and passes a current through the 
door lock actuators of all doors for 0.25 seconds 
to unlock all doors. Due to this, there may be a 
time lag between the driver’s or front passenger's 
door lock switch actuation and the time when all 
doors are unlocked. 

GENERAL DESCRIPTION
SIMPLIFIED WIRING SYSTEM (SWS)54B-5
INTERMITTENT CONTROL
ETACS-ECU uses the dial position of the variable 
intermittent wiper control switch and the vehicle 
speed signal sent by the combination meter to calcu-
late the interval to be sent to the front-ECU. The 
front-ECU determines the intermittent time from the 
input SWS data signal, and turns ON the windshield 
wiper drive signal. When the wiper is at the STOP 
position, the windshield wiper auto-stop signal goes 
OFF to turn OFF the windshield wiper drive signal. 
After the intermittent time from when the windshield 
wiper drive signal turned ON, the windshield wiper 
drive signal is turned ON again and the above opera-
tion is repeated.
.
MIST WIPER CONTROL
When the ignition switch is in the ACC or ON posi-
tion, and the windshield mist wiper switch of the col-
umn switch is turned ON, the front-ECU turns ON the 
windshield wiper drive signal. At the same time, the 
wiper speed switching relay is turned ON 
(HIGH-SPEED). While the windshield mist wiper 
switch is ON, the windshield wiper will operate at 
high speed. Then, if the windshield mist wiper switch 
is turned off, the wiper operates at low speed until it 
stops at the predetermined park position.
When the windshield mist switch is turned on briefly, 
the wiper operates once at low speed.
At the point the windshield mist switch is turned ON, 
if the windshield wiper has been operating intermit-
tently, the same operations as the above will be per-
formed while the windshield mist wiper switch is ON. 
After the windshield mist wiper switch goes OFF, the 
intermittent operations will be set again after the 
windshield wiper auto-stop signal last is turned ON.
.
WASHER CONTROL
When the ignition switch is in the ACC or ON posi-
tion, and the windshield washer switch of the column 
switch is turned ON, the front-ECU turns ON the 
windshield washer relay. The windshield wiper drive 
signal is turned ON in 0.15 seconds until 2 seconds 
after the windshield washer switch goes OFF to 
operate the windshield wiper continuously. When the 
windshield washer switch is turned ON, if the wind-
shield wiper is operating intermittently, intermittent 
operations will be continued after continuous opera-
tions.
HEADLAMP
.
HEADLAMP AUTOMATIC SHUTDOWN 
FUNCTION
Even if the lighting switch (tail lamp switch or 
headlamp switch) is ON, the headlamps and tail 
lamps will automatically go off in the following condi-
tions to prevent the battery from discharging:
When the ignition key is turned from "ON" to "LOCK" 
(OFF) or "ACC" position with the lighting switch 
turned ON, and this state continues for three min-
utes, the lamp will automatically be turned off. If the 
driver's seat door is opened during these three min-
utes, the lamp will go off one second later.
.
HIGH-BEAM INDICATOR
At the same time that the high beams are illumi-
nated, the ETACS-ECU sends a signal to illuminate 
the high-beam indicator via the CAN bus line. The 
combination meter receives the transmitted signal 
and turns the high-beam indicator on and off.
FLASHER TIMER
.
TURN-SIGNAL LAMP
The turn-signal lamp output (flashing signal) is 
turned ON when the ignition switch is ON and the 
turn-signal lamp switch is ON (LH or RH). If the front 
turn-signal lamp or rear turn-signal lamp bulb has 
burned out, the flashing speed increases to indicate 
that the bulb has burned out.
.
HAZARD WARNING LAMP
Detects the signal where the hazard warning lamp 
switch input changes from OFF to ON, and reverse 
the flashing state according to this signal. The haz-
ard warning lamps toggle on and off whenever the 
hazard warning lamp switch is operated.
.
TURN-SIGNAL INDICATORS
At the same time that the turn-signal lamps are illu-
minated, the ETACS-ECU sends a signal to illumi-
nate the turn-signal lamp indicator via the CAN bus 
line. The combination meter receives the transmitted 
signal and turns the turn-signal lamp indicator on and 
off. 

GENERAL DESCRIPTION
SIMPLIFIED WIRING SYSTEM (SWS)54B-7
SEAT BELT INDICATOR
If any of the following conditions is met with the igni-
tion switch at "ON" or "ST", the ETACS-ECU illumi-
nates, flashes or extinguishes the seat belt indicator 
by using the driver's seat belt switch signal and the 
vehicle speed signal sent from the combination 
meter.
Illuminates when the ignition switch is at "ON" 
and the seat belt switch is turned on (the driver's 
seat belt is unfastened).
Flashes and illuminates the indicator 12 cycles 
(after 0.5 seconds) if any of the following condi-
tions is met when sixty seconds or more have 
elapsed since the ignition switch is turned "ON". 
One cycle consists of five-second "flashing" and 
then three-second "illumination".
a. The vehicle speed has reached 8 km/h (5 
mph) while the seat belt switch is turned on 
(driver's seat belt is not fastened) with the 
ignition switch "ON.
b. The seat belt switch has been turned on 
(driver's seat belt has not been fastened) for 
at least ten seconds while the ignition switch 
has been turned "ON" and the vehicle speed 
has been 8 km/h (5 mph) or more.
NOTE: Once this timer operation has been acti-
vated, it will not be activated again until the 
vehicle speed reduces to 3 km/h (2 mph) or 
less even if any of the following conditions is 
met.
The indicator stops illuminating if the ignition 
switch or the seat belt switch is turned off (the 
driver's seat belt is fastened) while the timer 
operation is active. 
DOOR-AJAR INDICATOR LAMP
The combination meter receives the signal sent from 
the ETACS-ECU about whether each door or trunk is 
open or closed and turns the door ajar indicator lamp 
on and off. While the door ajar indicator is illumi-
nated, the door ajar warning function is activated and 
the door ajar indicator lamp flashes 4 times. If the 
door remains open even after the 4 warning flashes, 
the door ajar indicator lamp will be illuminated again.
CONFIGURATION FUNCTION
The following functions can be adjusted by operating 
the middle-grade multi center display (if equipped).
Keyless entry horn answerback function
Keyless entry hazard lamp answerback function
Timed locking mechanism
Turn-signal lamp buzzer
Door ajar warning buzzer
Adjustment of door unlocking operation on key-
less entry system
Vehicle speed-dependent wiper function
Headlamp automatic shutdown function
Delay-off time of the dome lamp
Interior lamp automatic shutoff function
Initialisation of above mentioned functions 

SWS DIAGNOSIS
SIMPLIFIED WIRING SYSTEM (SWS)54B-17
ETACS
NOTE:  For item No.43, the diagnostic tool 
MB991958 (MUT-III Sub Assembly) also displays 
"ON" when the lamp reminder tone alarm or the seat 
belt tone alarm function is triggered.
.
CHECK 
ITEMITEM NO. DISPLAY ON 
DIAGNOSTIC 
TOOLCHECK CONDITION NORMAL 
CONDITION
Tone alarm 43 BUZZER When requirements for sounding each 
warning tone alarm are not satisfiedOFF
Front fog 
lamps36 F.FOG LAMP
1.  Lighting switch: HEAD
2.  Fog lamp switch: ONON
Other than the condition above OFF
Driver’s door 
switch32 FRONT DOOR 
SWDriver’s door switch and Front passenger’s 
door switch is on ON
Driver’s door switch and Front passenger’s 
door switch is offOFF
Headlamp 
automatic 
shutoff 
function35 H/L AUTO-CUT
1.  Lighting switch: Other than OFF
2.  Ignition switch: from ON or START to 
LOCK (OFF) or ACC
3.  Front door switch: ON (front door open) OFF to ON (after 
approximately one 
second)
When requirements for the headlamp 
automatic shutoff are not satisfiedOFF
Ignition 
switch (ACC)31 IG SW (ACC) Ignition switch: ACC or ON ON
Ignition switch: LOCK (OFF) or START OFF
Ignition 
switch (IG1)30 IG SW (IG1) Ignition switch: ON or START ON
Ignition switch: LOCK (OFF) or ACC OFF
Windshield 
intermittent 
wiper interval37 INT WIPE 
TIME1.  Ignition switch: ACC or ON
2.  Operate the intermittent wiper control, 
and change the wiper intervalThe diagnostic tool 
MB991958 
(MUT-III Sub 
Assembly) 
displays 
intermittent wiper 
interval in 
response to the 
intermittent wiper 
control positions. 

SYMPTOM CHART
SIMPLIFIED WIRING SYSTEM (SWS)54B-57
SYMPTOM CHARTM1549000801159
ECU COMMUNICATION SYSTEM
FUNCTION SYSTEM
SYMPTOM INSPECTION 
PROCEDUREREFERENCE 
PA G E
Communication with the SWS monitor kit is not possible. A-1
P.54B-63
Communication with the column switch (column-ECU) is not possible. A-2
P.54B-68
Communication with the ETACS-ECU is not possible. A-3
P.54B-74
Communication with the front-ECU is not possible. A-4
P.54B-80
Communication with the sunroof-ECU is not possible. A-5
P.54B-87
SYSTEM SYMPTOM INSPECTION 
PROCEDUREREFERENCE 
PA G E
Tone alarm General description concerning the tone alarm
P.54B-94
Light reminder tone alarm function does not work 
normally.B-2
P.54B-98
Seat belt tone alarm function does not work 
normally.B-3
P.54B-101
Door ajar warning buzzer function does not work 
normally.B-4
P.54B-106
The multi center display does not sound normally 
when it is operated. 
P.54B-112
Turn-signal lamp buzzer function does not work 
normally.B-6
P.54B-116
Central door locking 
systemGeneral description concerning central door 
locking system
P.54B-118
The central door locking system does not work at 
all.C-1
P.54B-122
Some doors do not lock or unlock. C-2
P.54B-129
All the doors do not lock or unlock with just the 
door lock switch operation.C-3
P.54B-142
All the doors do not lock or unlock with just the 
door lock key cylinder key operation.C-4
P.54B-143
Forgotten key prevention function does not work 
normally.C-5
P.54B-144 

SYMPTOM CHART
SIMPLIFIED WIRING SYSTEM (SWS)54B-60
Interior lamp General description concerning the interior lampP.54B-355
The dome lamp do not illuminate and go out 
normally.K-1
P.54B-359
The front dome lamp, rear dome lamp or trunk 
lamp do not illuminate or go out normally.K-2
P.54B-366
Dome lamp dimming function does not work 
normally.K-3
P.54B-376
The ignition key hole illumination lamp does not 
illuminate or go out normally.K-4
P.54B-381
The interior lamp automatic shutoff function does 
not work normally.K-5
P.54B-389
The door ajar indicator lamps do not illuminate or 
go out normallyK-6
P.54B-394
The seat belt warning lamp do not illuminate or go 
out normallyK-7
P.54B-398
Can not customize the functions by operating the multi center display . L-1
P.54B-402 SYSTEM SYMPTOM INSPECTION 
PROCEDUREREFERENCE 
PA G E 

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-94
NOTE: Also check intermediate connector C-27 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the 
connector. If intermediate connector C-27 is damaged, repair or 
replace the damaged component(s) as described in GROUP 
00E, Harness Connector Inspection P.00E-2.
Q: Is the wiring harness between sunroof motor assembly 
connector D-04 (terminal 10) and ETACS-ECU connector 
C-218 (terminal 53) in good condition?
YES : Go to Step 10.
NO : The wiring harness may be damaged or the 
connector(s) may have loose, corroded or damaged 
terminals, or terminals pushed back in the connector. 
Repair the wiring harness as necessary. The system 
should communicate with the sunroof-ECU normally.
STEP 10. Replace the sunroof motor assembly.
(1) Replace the sunroof motor assembly.
(2) The system should communicate with the sunroof-ECU 
normally.
Q: Can the system communicate with the sunroof-ECU?
YES : No action is necessary and testing is complete.
NO : Replace the ETACS-ECU. The system should 
communicate with the sunroof-ECU normally.
TONE ALARM
GENERAL DESCRIPTION CONCERNING THE TONE ALARMM1549021000326
The tone alarm functions are as follows. These func-
tions are controlled by relevant ECUs.
FUNCTION CONTROL ECU
Light reminder tone alarm function ETACS-ECU, column switch
Seat belt tone alarm function ETACS-ECU
Door ajar warning buzzer ETACS-ECU
Center display operation tone 
Turn-signal lamp buzzer ETACS-ECU, column switch 

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-95
Light reminder tone alarm function
When the taillights or headlamps is the ON position, if the igni-
tion key is removed and the driver's door is opened, a tone 
alarm will sound continuously to warn that the lamps are on. 
However, if the taillights or headlamps have been turned off by 
the headlamp automatic-shutoff function, the tone alarm will not 
sound.
Seat belt tone alarm function