Page 87 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-87
INSPECTION PROCEDURE A-5: Communication with the Sunroof-ECU is not Possible.
.
CIRCUIT OPERATION
Power to the sunroof motor assembly is supplied
through fusible link (5).
When the ignition switch (IG2) signal is on, the
sunroof motor assembly is ready to operate.
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
.
TECHNICAL DESCRIPTION (COMMENT)
The power supply circuit or the communication circuit
to the sunroof motor assembly or the sunroof motor
assembly may be defective.
.
TROUBLESHOOTING HINTS
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector
The sunroof motor assembly may be defective
The ETACS-ECU may be defective
Page 91 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-91
STEP 4. Check the ignition switch (IG2) circuit to the
sunroof motor assembly. Measure the voltage at sunroof
motor assembly connector D-04.
(1) Disconnect sunroof motor assembly connector D-04 and
measure the voltage available at the wiring harness side of
the connector.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal 2 and ground.
The voltage should measure approximately 12 volts
(battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery
positive voltage)?
YES : Go to Step 6.
NO : Go to Step 5.
STEP 5. Check the wiring harness between sunroof motor
assembly connector D-04 (terminal 2) and ignition switch
(IG2).
Page 92 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-92
NOTE: Also check junction block connectors C-215 and C-205
for loose, corroded, or damaged terminals, or terminals pushed
back in the connector. If junction block connector C-215 or
C-205 is damaged, repair or replace the damaged compo-
nent(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 2) and the ignition switch (IG2)
in good condition?
YES : No action is necessary and testing is complete.
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 6. Check the ground circuit to the sunroof motor
assembly. Measure the resistance at sunroof motor
assembly connector D-04.
(1) Disconnect sunroof motor assembly connector D-04 and
measure the resistance available at the wiring harness side
of the connector.
(2) Measure the resistance value between terminal 5 and
ground.
The resistance should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES : Go to Step 8.
NO : Go to Step 7.
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 98 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-98
54B
INSPECTION PROCEDURE B-2: Tone Alarm: Light Reminder 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 operates the light reminder tone
alarm function according to the following signals:
Ignition switch (IG1): OFF
Ignition key reminder switch: ON
Front door switch (RH): ON
Taillamp switch: ON
Headlamp switch: ON
The ETACS-ECU operates the lamp reminder tone
alarm function under the following conditions:
Ignition switch: "LOCK" (OFF) position
Ignition key: Removed from the ignition key cylin-
der
Driver’s door: open
Taillamps or headlamps: ON
.
TECHNICAL DESCRIPTION (COMMENT)
If the function does not work normally, the input cir-
cuit system from the switches or the ETACS-ECU
may be defective (refer to "CIRCUIT OPERATION").
.
TROUBLESHOOTING HINTS
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
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
DIAGNOSIS
Required Special Tools:
MB991223: Harness Set
MB991958: diagnostic tool (MUT-III Sub Assembly)
MB991824: Vehicle Communication Interface (V.C.I.)
MB991827: MUT-III USB Cable
MB991910: MUT-III Main Harness A
MB991813: SWS Monitor Kit
MB991806: SWS Monitor Cartridge
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 106 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-106
INSPECTION PROCEDURE B-4: Tone Alarm: Door ajar Warning Buzzer 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 controls the door-ajar warning tone
alarm, based on the signals from the switches and
sensors below.
Ignition switch (IG1): ON
One of the door switches: ON
Vehicle speed signal: 8 km/h (5 mph) or more
.
TECHNICAL DESCRIPTION (COMMENT)
If the door-ajar warning tone alarm does not work,
connector(s), wiring harness in the CAN bus lines,
the combination 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 combination meter may be defective
The ETACS-ECU may be defective
Page 142 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-142
INSPECTION PROCEDURE C-3: Central Door Locking System: All the Doors do not Lock or Unlock
with just the Door Lock Switch Operation.
.
TECHNICAL DESCRIPTION (COMMENT)
The door lock switch (incorporated in the power win-
dow main switch and front power window sub switch)
or the ETACS-ECU 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
DIAGNOSIS
Required Special Tools:
MB991223: Harness Set
MB991958: diagnostic tool (MUT-III Sub Assembly)
MB991824: Vehicle Communication Interface (V.C.I.)
MB991827: MUT-III USB Cable
MB991910: MUT-III Main Harness A
Check the input signal (by using the pulse check mode of
the monitor).
Check the input signals from the door lock switch (incorporated
in the power window main switch and front power window sub
switch):
To prevent damage to diagnostic tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting diagnostic tool
MB991958.
(1) Connect the special tool. Refer to "How to connect SWS
monitor P.54B-13."
(2) When the driver's or the front passenger's door lock switch
is moved from "LOCK" to "UNLOCK" and vice versa, check
if diagnostic tool MB991958 sounds or not.
(3) Operate diagnostic tool MB991958 according to the
procedure below to display "Pulse check."
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "Pulse Checking."
Q: Does diagnostic tool MB991958 sound when the driver's
or the front passenger's door lock switch is moved from
"LOCK" to "UNLOCK" and vice versa?
YES : Replace the ETACS-ECU. Check that all the doors
should be locked and unlocked by the door lock
switch.
NO : Refer to Inspection Procedure N-6 "ETACS-ECU
does not receive any signal from the door lock switch
(incorporated in the power window main switch and
front power window sub switch) P.54B-460."