
54B-1
GROUP 54B
SIMPLIFIED WIRING 
SYSTEM (SWS)
CONTENTS
GENERAL DESCRIPTION. . . . . . . . .54B-2
COMMUNICATION METHOD  . . . . . . . . . . 54B-2
OPERATION . . . . . . . . . . . . . . . . . . . . . . . . 54B-2
SPECIAL TOOL . . . . . . . . . . . . . . . . .54B-8
SWS DIAGNOSIS  . . . . . . . . . . . . . . .54B-10
GENERAL DESCRIPTION . . . . . . . . . . . . . 54B-10
BEFORE CARRYING OUT 
TROUBLESHOOTING  . . . . . . . . . . . . . . . . 54B-10
DIAGNOSTIC FUNCTION  . . . . . . . . . . . . . 54B-10
SWS DIAGNOSTIC TROUBLESHOOTING 
STRATEGY . . . . . . . . . . . . . . . . . . . . . . . . . 54B-12
HOW TO CONNECT SWS MONITOR . . . . 54B-13
HOW TO CHECK ECUS . . . . . . . . . . . . . . . 54B-15
SERVICE DATA CHECK  . . . . . . . . . . . . . . 54B-15
PULSE CHECK . . . . . . . . . . . . . . . . . . . . . . 54B-24
DIAGNOSTIC TROUBLE CODE 
CHART . . . . . . . . . . . . . . . . . . . . . . . .54B-25
DIAGNOSTIC TROUBLE CODE 
PROCEDURES  . . . . . . . . . . . . . . . . .54B-25
SYMPTOM CHART  . . . . . . . . . . . . . .54B-57
INPUT SIGNAL CHART . . . . . . . . . . .54B-61
SYMPTOM PROCEDURES . . . . . . . .54B-63
TONE ALARM . . . . . . . . . . . . . . . . . . . . . . . 54B-94
GENERAL DESCRIPTION CONCERNING 
THE TONE ALARM. . . . . . . . . . . . . . . . . . . 54B-94
CENTRAL DOOR LOCKING SYSTEM. . . . 54B-118GENERAL DESCRIPTION CONCERNING 
CENTRAL DOOR LOCKING SYSTEM . . . . 54B-118
POWER WINDOWS  . . . . . . . . . . . . . . . . . . 54B-148
GENERAL DESCRIPTION CONCERNING 
THE POWER WINDOWS  . . . . . . . . . . . . . . 54B-148
KEYLESS ENTRY SYSTEM . . . . . . . . . . . . 54B-187
GENERAL DESCRIPTION CONCERNING 
THE KEYLESS ENTRY SYSTEM . . . . . . . . 54B-187
SUNROOF . . . . . . . . . . . . . . . . . . . . . . . . . . 54B-209
GENERAL DESCRIPTION CONCERNING 
THE SUNROOF  . . . . . . . . . . . . . . . . . . . . . 54B-209
WINDSHIELD WIPER AND WASHER  . . . . 54B-223
GENERAL DESCRIPTION CONCERNING 
THE WINDSHIELD WIPER AND WASHER  54B-223
HEADLAMP AND TAILLAMP  . . . . . . . . . . . 54B-257
GENERAL DESCRIPTION CONCERNING 
THE HEADLAMPS AND TAILLAMPS . . . . . 54B-257
FLASHER TIMER  . . . . . . . . . . . . . . . . . . . . 54B-309
GENERAL DESCRIPTION CONCERNING 
THE FLASHER TIMER  . . . . . . . . . . . . . . . . 54B-309
FOG LAMP  . . . . . . . . . . . . . . . . . . . . . . . . . 54B-339
GENERAL DESCRIPTION CONCERNING 
THE FOG LAMPS . . . . . . . . . . . . . . . . . . . . 54B-339
INTERIOR LAMP . . . . . . . . . . . . . . . . . . . . . 54B-355
GENERAL DESCRIPTION CONCERNING 
THE INTERIOR LAMP  . . . . . . . . . . . . . . . . 54B-355
INPUT SIGNAL PROCEDURES . . . . .54B-405
CHECK AT ECU TERMINAL  . . . . . . .54B-480
ON-VEHICLE SERVICE . . . . . . . . . . .54B-486
CONFIGURATION FUNCTION . . . . . . . . . . 54B-486 

GENERAL DESCRIPTION
SIMPLIFIED WIRING SYSTEM (SWS)54B-2
GENERAL DESCRIPTION
COMMUNICATION METHODM1549013000547
As shown in the figure, SWS communications con-
nect the ETACS*
1-ECU, the column switch (in the 
column-ECU), the front-ECU, and the sunroof-ECU. 
CAN*
2*3 communications connect the ETACS-ECU, 
the powertrain control module, the A/C-ECU, the 
SRS-ECU, the combination meter, the ABS-ECU, 
and the middle-grade multi center display. These two 
communications groups are connected to form a 
dedicated network for sending multiplex data.NOTE: *
1ETACS: Electronic Time and Alarm Control 
System
NOTE: *
2CAN: Controller Area Network
NOTE: *
3: For details on CAN, see Group 54C.
OPERATIONM1549013100566
TONE ALARM FUNCTION
.
TRIP COMPUTER TONE ALARM FUNC-
TION 
The ETACS-ECU sounds the buzzer when the 
buzzer signal is sent from the combination meter.
.
LAMP REMINDER TONE ALARM 
FUNCTION
When the taillamps or headlamps are ON, if the igni-
tion key is on "OFF" and the driver's door is opened, 
a tone alarm will sound continuously to warn that the 
lamp is illuminated. However, if the taillamps or 
headlamps have been turned off by the headlamp 
automatic-shutdown function, the tone alarm will not 
sound.
. 

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-4
.
FORGOTTEN KEY PREVENTION 
FUNCTION
If the driver's door is locked while it is open and 
when the key is still in the ignition key cylinder, 
approximately 0.3 second later the ETACS-ECU 
activates the unlock relay output for 0.25 second 
to prevent the door from being locked with the 
key inside the vehicle. In addition, if locking the 
door was not prevented, a re-try current is sent 
(an unlock relay output ON is sent for 0.25 sec-
ond up to 5 times including the first attempt).
If the passenger's door or driver's door are locked 
while the passenger's door is open and when the 
key is still in the ignition key cylinder, approxi-
mately 0.3 second later the ETACS-ECU acti-
vates the unlock relay output for 0.25 second to 
prevent the door from being locked with the key 
inside the vehicle. In addition, if locking the door 
was not prevented, a re-try current is sent (an 
unlock relay output ON is sent for 0.25 second up 
to 5 times including the first attempt).
POWER WINDOW RELAY CONTROL
.
POWER WINDOW RELAY OPERATION
If the ignition switch is turned to "ON" or "ACC" posi-
tion, the power window relay is energized to activate 
the power windows.
.
POWER WINDOW TIMER FUNCTION
Even after the ignition is switched off, the 
ETACS-ECU keeps the power window relay acti-
vated for approximately 30 seconds, enabling raising 
and lowering of the power windows by using the 
power window switches. After approximately 30 sec-
onds, the power window relay is deactivated. During 
this timed operation, if the driver or passenger doors 
are opened, the power window relay is deactivated 
from that moment.
KEYLESS ENTRY SYSTEM
.
KEYLESS ENTRY HAZARD ANSWER-
BACK FUNCTION
If the keyless entry transmitter is used to send a lock 
signal to the ETACS-ECU, all doors, the liftgate, and 
the glass hatch are locked and the hazard warning 
lamps flash once. If an unlock signal is sent, the 
driver's door is unlocked first, and if a second signal 
is sent, all doors, the liftgate, and the glass hatch are 
unlocked. Each time the unlock signal is sent, the 
hazard warning lamps flash twice.
.
KEYLESS ENTRY HORN ANSWERBACK 
FUNCTION
If the keyless entry transmitter is used to send 2 lock 
signals to the ETACS-ECU, the first signal locks all 
doors, while the second signal sounds the horn once.
.
TRUNK UNLOCK FUNCTION
Press the "TRUNK" button twice within 5 seconds 
and the trunk lid will be unlocked.
.
TIMED LOCKING MECHANISM
After unlocking the doors with the keyless entry 
transmitter, if no doors are opened or if the ignition 
key is not inserted, the ETACS-ECU automatically 
locks the doors in 30 seconds.
SUNROOF CONTROL
.
SUNROOF TIMER FUNCTION
The ETACS-ECU enables opening and closing of the 
sunroof for 30 seconds after the ignition is switched 
off. During this timed operation, if the driver's or front 
passenger’s door is opened, the sunroof timer func-
tion is deactivated from that moment.
WINDSHIELD WIPERS AND WASHERS
.
LOW SPEED WIPER, HIGH SPEED WIPER 
CONTROL
When the ignition switch in at the ACC or ON 
position, and the windshield low speed wiper 
switch of the column switch is turned ON, the 
front-ECU turns ON the windshield wiper drive 
signal, turns OFF (LO) the windshield wiper 
speed relay, and operates the windshield wiper at 
low speed.
When the windshield high speed wiper switch is 
turned ON, the windshield wiper drive signal is 
turned ON, the windshield wiper speed switching 
relay is turned ON (HI), and the windshield wiper 
is operated at high speed.
. 

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-6
FOG LAMP
.
FOG LAMP
The fog lamps will illuminate only when the fog lamp 
switch is operated while the low-beam headlamps 
are on.
The fog lamps will be switched off when any of the 
following conditions is met. The fog lamps will also 
be switched off automatically by headlamp automatic 
shutdown function.
When the high-beam headlamps are switched 
on, the fog lamps will be switched off. If the 
low-beam headlamps are switched on again, the 
fog lamps will illuminate again.
When the headlamp switch is turned off while the 
tail lamps are on or the tail lamps and headlamps 
are off, the fog lamps will be switched off. If the 
low-beam headlamps are switched on again, the 
fog lamps will not illuminate again.
.
FOG LAMP INDICATOR
At the same time that the fog lamps are illuminated, 
the ETACS-ECU sends a signal to illuminate the fog 
lamp indicator via the CAN bus line. The combination 
meter receives the transmitted signal and turns the 
fog lamp indicator on and off.
INTERIOR LAMP
ETACS-ECU makes it possible to force operation of 
all ON and OFF lamp switches in the overhead con-
sole (the dome lamp, reading lamp, cargo area lamp, 
rear personal lamps, front door lamps, and front foot 
lamps). This function is assigned higher priority than 
the controls for the interior lamp switch that are per-
formed when the doors are in certain positions.
When the lamps are forced on, the illumination 
level is 100% as all interior lamps are switched on 
(the dome lamp, reading lamp, cargo area lamp, 
rear personal lamps, front door lamps, and front 
foot lamps). Even when all lamps are forced on, 
the interior lamp automatic shutoff function is 
active.
When the lamps are forced off, all interior lamps 
are immediately switched off (the dome lamp, 
reading lamp, cargo area lamp, rear personal 
lamps, front door lamps, and front foot lamps).When the interior lamp switch is at DOOR position, 
the ETACS-ECU controls the interior lamps as fol-
lows:
When a door is opened with the ignition switch 
off, the interior lamps up to a luminance of 100 
percent. When a door is closed, the interior lamps 
dims a luminance of 65 percent, and goes off 30 
seconds later. However, if the ignition switch is 
turned ON or if a door is locked while the interior 
lamps is dimming, the dome lamp will go off at 
that point.
When a door is opened with the ignition switch 
ON, the interior lamps up at a luminance of 100 
percent. When all doors are closed, the interior 
lamps go off.
When the ignition key is removed with all doors 
closed, the interior lamps up at a luminance of 
100 percent, and goes off 30 seconds later. How-
ever, if the ignition key is inserted again or if a 
door is locked while the interior lamps is lighting, 
the interior lamps will go off at that point.
To check keyless entry operations more easily, 
the interior lamps will flash twice when doors are 
locked. When doors are unlocked, the interior 
lamps up at a luminance of 100 percent, and 
goes off 15 seconds later.
INTERIOR LAMP AUTOMATIC 
SHUTDOUN FUNCTION
Illuminated interior lamps such as the front dome 
lamp, etc. (all lamps using the dome lamp fuse as the 
power supply) will automatically go off in the follow-
ing conditions to prevent the battery from discharging 
as a result of forgetting to turn off the lamps or 
incomplete closing of the door.
When the ignition switch is turned off and more 
than 30 minutes pass by with the interior lamp 
illuminated, the interior lamps will go off automati-
cally.
When the ignition switch is turned off and one of 
the door switches remains open for 30 minutes 
continuously, the interior lamps will go off auto-
matically. 

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 

SPECIAL TOOL
SIMPLIFIED WIRING SYSTEM (SWS)54B-8
SPECIAL TOOLM1549000301035
TOOL TOOL NUMBER 
AND NAMESUPERSESSION APPLICATION
MB991958
A: MB991824
B: MB991827
C: MB991910
D: MB991911
E: MB991914
F: MB991825
G: MB991826
MUT-III sub 
assembly
A: Vehicle 
communication 
interface (V.C.I.)
B: MUT-III USB 
cable
C: MUT-III main 
harness a 
(vehicles with 
CAN 
communication 
system)
D: MUT-III Main 
Harness B 
(Vehicles without 
CAN 
communication 
system)
E: MUT-III main 
harness C (for 
Daimler Chrysler 
models only)
F: MUT-III 
measurement 
adapter
G: MUT-III trigger 
harnessMB991824-KIT
NOTE: . G: 
MB991826 MUT-III 
Trigger Harness is not 
necessary when 
pushing V.C.I. ENTER 
key.SWS communication line check 
(ECU check and service data)
For vehicles with CAN 
communication, use MUT-III 
main harness A to send 
simulated vehicle speed. If you 
connect MUT-III main harness B 
instead, the CAN 
communication does not 
function correctly.