Page 96 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-96
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-second "on" and then three-second 
"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 (5 mph) 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.  
         
        
        
     
        
        Page 97 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-97
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 ignition is switched ON and 
the vehicle speed reaches 8 km/h (5 mph) or faster. The buzzer 
will continue to sound for 4 times even if the ignition, door sta-
tus, or vehicle speed requirements are not maintained.
NOTE: The warning buzzer can be customized on vehicles 
equipped with a multi center display.  Refer to P.54B-486.
Multi center display operation tone 
center display >
The ETACS-ECU sounds the buzzer when the buzzer signal is 
sent from the center display.
Turn-signal lamp buzzer
The ETACS-ECU sounds the buzzer in sync with the turn-sig-
nal lamps or hazard warning lamps.
NOTE: The turn-signal lamp buzzer can be customized on 
vehicles equipped with a multi center display (middle grade 
type).  Refer to P.54B-486.
General circuit diagram for lamp reminder tone alarm function. P.90-111
General circuit diagram for seat belt tone alarm function. P.90-113 
         
        
        
     
        
        Page 101 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-101
Normal condition is not displayed for "FRONT DOOR 
SW" : Refer to Inspection Procedure M-4 "ETACS-ECU 
does not receive any signal from the front door 
switches P.54B-413."
Normal condition is not displayed for "H/L AUTO-CUT" : 
Refer to Inspection Procedure H-9 "Headlamp 
automatic shutoff function does not work normally 
P.54B-305."
Normal condition is not displayed for "BUZZER" : 
Replace the ETACS-ECU. The lamp reminder tone 
alarm function should now work normally.
INSPECTION PROCEDURE B-3: Tone Alarm: Seat Belt Tone Alarm Function does not Work Normally.
NOTE: This troubleshooting procedure requires the 
use of diagnostic tool MB991958 and SWS monitor 
kit MB991813. For details on how to use the SWS 
monitor, refer to "How to connect SWS monitor 
P.54B-13."
.
CIRCUIT OPERATION
The ETACS-ECU receives the driver's seat belt 
switch ON signal from the ignition switch (IG1) and 
the combination meter, and then controls the seat 
belt tone alarm function.
The ETACS-ECU operates the seat belt tone alarm 
function under the following conditions:
Ignition switch: "ON" position
Driver's seat belt: Unfastened
.
TECHNICAL DESCRIPTION (COMMENT)
If the seat belt tone alarm does not work, connec-
tor(s), wiring harness in the CAN bus lines, the com-
bination meter, the ETACS-ECU or the input signal 
circuit may be defective.
.
TROUBLESHOOTING HINTS
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
Trouble in input signal system
The wiring harness or connectors may have 
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector
The ETACS-ECU may be defective 
         
        
        
     
        
        Page 105 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-105
STEP 4. Check the input signal by using "FUNCTION 
DIAG." menu of the SWS monitor.
Check the input signals from the following switches:
Ignition switch: OFF  ON
Driver's seat belt: Unfastened
All door: Closed
(1) Operate diagnostic tool MB991958 according to the 
procedure below to display "OTHER ALARM"
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "BUZZER."
g. Select "OTHER ALARM"
(2) Check that normal conditions are displayed for the items 
described in the table below.
NOTE: Turn the ignition switch from the OFF position to the 
ON position. Then item No.43 should be ON for approxi-
mately six seconds only.
Q: Does diagnostic tool MB991958 display the items "IG 
SW (IG1)" and "BUZZER" as normal condition?
Normal conditions are displayed for all the items : 
Replace the ETACS-ECU. Verify that the seat belt 
tone alarm function works normally.
Normal condition is not displayed for "IG SW (IG1)" : 
Refer to Inspection Procedure M-2 "ETACS-ECU 
does not receive any signal from the ignition switch 
(IG1) P.54B-408."
Normal condition is not displayed for "BUZZER" : 
Replace the ETACS-ECU. Verify that the seat belt 
tone alarm function works normally. ITEM NO. ITEM NAME NORMAL CONDITION
ITEM 30 IG SW (IG1) ON
ITEM 43 BUZZER ON (for approximately six 
seconds after the ignition 
switch is turned from OFF 
to ON), and then OFF 
         
        
        
     
        
        Page 259 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-259
Headlamp automatic-shutdown function
Even if the lighting switch (taillamps switch or headlamp switch) 
is ON, the headlamps (including the taillamps) will automati-
cally go off in the following conditions to prevent the battery 
from discharging as a result of forgetting to turn off lamps.
If 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 minutes, the headlamps will automati-
cally be turned off. If the driver's seat door is opened during 
these three minutes, the headlamps will go off one second 
later.
NOTE: The headlamp automatic-shutoff function can be cus-
tomized on vehicles equipped with a multi center display (mid-
dle grade type). Refer to P.54B-486.
Dimmer automatic reset function
If the headlamp switch is turned off while the high-beam 
headlamps are on, the dimmer switch will be reset. Because of 
this, the headlamps will illuminate at low beam the next time 
that they are turned on. The dimmer switch will be also reset if 
the dimmer switch is turned on unintentionally while the pass-
ing switch is operated. 
         
        
        
     
        
        Page 355 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-355
54B
INTERIOR LAMP
GENERAL DESCRIPTION CONCERNING THE INTERIOR LAMPM1549021800236
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80The following ECUs affect the functions and control 
of the interior lamps.
Interior lamp control function
The ETACS-ECU controls the interior lamps by turn-
ing them on and off in the following way:
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 at 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 a door is 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 is flashed once when the doors 
are locked. When the doors are unlocked, the 
interior lamps at a luminance of 100 percent, and 
go off 15 seconds later.
NOTE: The dimmer function can be customised on 
vehicles equipped with a multi center display (middle 
grade type).  Refer to P.54B-486.
NOTE: The dotted lines indicate that lighting mode 
when the ignition switch is turned ON, door is locked, 
or any door is opened during the timer illumination 
time. FUNCTION CONTROL ECU
Interior lamp control function ETACS-ECU
Interior lamp automatic-shutoff function ETACS-ECU
Ignition key hole illumination lamp function ETACS-ECU
Door ajar indicator ETACS-ECU
Seat belt indicator ETACS-ECU 
         
        
        
     
        
        Page 357 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-357
Seat belt indicator 
         
        
        
     
        
        Page 358 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-358
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.