Page 23 of 1500

SWS DIAGNOSIS
SIMPLIFIED WIRING SYSTEM (SWS)54B-23
For checking item "HEADLAMP HI", the diagnostic
tool MB991958 (MUT-III Sub Assembly) displays
"OFF" on the item No.2 "DIMMER SW" when the
headlamps are at high-beam. Therefore, the
diagnostic tool MB991958 (MUT-III Sub Assembly)
should display "ON" momentarily when the dimmer
switch is operated.
.
TURN SIGNAL
.
BUZZER
NOTE: The headlamp automatic shutoff function
operates approximately one second after the lighting
monitor tone alarm starts sounding, and then the
tone alarm ceases sounding.
.
ITEM ITEM NO. INPUT SIGNAL DISPLAY ON
DIAGNOSTIC TOOLNORMAL CONDITION
TURN-SIG.LH 10 Turn-signal lamp
switch (RH)T/S RH SW (COLUMN
ECU)OFF
11 Tu r n - s i g n a l l a m p
switch (LH)T/S LH SW (COLUMN
ECU)ON
30 Ignition switch
(IG1)IG SW (IG1) (ETACS ECU) ON
TURN-SIG.RH 10 Turn-signal lamp
switch (RH)T/S RH SW (COLUMN
ECU)ON
11 Tu r n - s i g n a l l a m p
switch (LH)T/S LH SW (COLUMN
ECU)OFF
30 Ignition switch
(IG1)IG SW (IG1) (ETACS ECU) ON
ITEM ITEM NO. INPUT SIGNAL DISPLAY ON DIAGNOSTIC
TOOLNORMAL CONDITION
LGT
MONI.ALRM00 Headlamp switch
HEADLAMP SW (COLUMN
ECU)Either is ON
01 Tail lamp switch TAILLAMP SW (COLUMN
ECU)
30 Ignition switch
(IG1)IG SW (IG1) (ETACS ECU) OFF
32 Front door switch FRONT DOOR SW (ETACS
ECU)ON
35 Headlamp
automatic shutoff
functionH/L AUTO-CUT (ETACS
ECU)OFF
43 Tone alarm BUZZER (ETACS ECU) ON
OTHER
ALARM30 Ignition switch
(IG1)IG SW (IG1) (ETACS ECU) ON
43 Tone alarm BUZZER (ETACS ECU) ON
Page 24 of 1500

SWS DIAGNOSIS
SIMPLIFIED WIRING SYSTEM (SWS)54B-24
SUNROOF
PULSE CHECK
M1549015100562
1. The input signals (signals other than SWS
communication line signals), which are
compatible with the SWS monitor by using the
diagnostic tool MB991958 (MUT-III Sub
Assembly) or voltmeter, can be confirmed by the
Pulse Check.2. Use the diagnostic tool MB991958 (MUT-III Sub
Assembly) or voltmeter to check the following
input signals.
NOTE: If a problem is found in the Pulse Check,
refer to Input Signal Chart P.54B-61.
Switches and their conditions, which are applicable
for Pulse CheckITEM ITEM NO. INPUT SIGNAL DISPLAY ON
DIAGNOSTIC TOOLNORMAL CONDITION
SUNROOF
OPE.30 Ignition switch
(IG1)IG SW (IG1) (ETACS ECU) ON
72 Response by the
sunroof-ECUS/R ECU ACK (SUNROOF
ECU)INPUT CHECK (only
momentarily when switch is
operated)
INPUT SIGNAL REQUIREMENTS FOR SOUNDING TONE
ALARM
Key reminder switch When the ignition key is pulled out
Hazard warning lamp switch When the switch is turned from off to on
Door switches A door is opened when all the doors are
closed
Door lock key cylinder switch When a door is locked or unlocked by a key
cylinder
Door lock actuators Move the door lock knob from lock position
to unlock position or vice versa
Door lock switch (incorporated in the power window main
switch and front power window sub switch)When a door is locked or unlocked by a door
lock switch
Keyless entry transmitter When the switch is turned from off to on
Interior lamp loaded signal Illuminates the interior lamps
Page 26 of 1500

DIAGNOSTIC TROUBLE CODE PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-26
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
MB991812: SWS Monitor Harness (For Column-ECU)
MB991822: Probe Harness
STEP 1. Using diagnostic tool MB991958, diagnose the
CAN bus line.
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 diagnostic tool MB991958. Refer to "How to
connect SWS monitor P.54B-13."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to GROUP 54C,
Diagnosis P.54C-5).
Page 27 of 1500
DIAGNOSTIC TROUBLE CODE PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-27
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Go to Step 3.
NO : There is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Cope with Intermittent
Malfunction P.00-14).
Page 28 of 1500

DIAGNOSTIC TROUBLE CODE PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-28
STEP 3. Use diagnostic tool MB991958 to select "ECU
COMM Check" on the SWS monitor display.
Check the following ECUs:
ETACS-ECU
Column switch (column-ECU)
Front-ECU
Sunroof-ECU
Connect special tool MB991910 before connecting special
tool MB991812. Be sure to connect special tool MB991806
after turning on special tool MB991824.
(1) Connect the SWS monitor. Refer to "How to connect SWS
monitor P.54B-13."
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Operate diagnostic tool MB991958 according to the
procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."
(4) DIAGNOSTIC TOOL MB991958 should show "OK" on the
"ECU COMM Check" menus for the "ETACS ECU",
"COLUMN ECU", "FRONT ECU" and "SUNROOF ECU"
menus.
Q: Are "OK" displayed for the "ETACS ECU," "COLUMN
ECU," "FRONT ECU" and "SUNROOF ECU" menus?
"OK" are displayed for all the items : It is determined that
there is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Cope with Intermittent
Malfunction P.00-14).
"NG" is displayed for the "ETACS ECU" menu : Refer to
Inspection Procedure A-3 "Communication with the
ETACS-ECU is not possible P.54B-74."
"NG" is displayed for the "COLUMN ECU" menu : Refer
to Inspection Procedure A-2 "Communication with the
column switch (column-ECU) is not possible
P.54B-68."
"NG" is displayed for the "FRONT ECU" menu : Refer to
Inspection Procedure A-4 "Communication with the
front-ECU is not possible P.54B-80."
"NG" is displayed for the "SUNROOF ECU" menu :
Refer to Inspection Procedure A-5 "Communication
with the sunroof-ECU is not possible P.54B-87."
Page 30 of 1500

DIAGNOSTIC TROUBLE CODE PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-30
STEP 1. Using diagnostic tool MB991958, diagnose the
CAN bus line.
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 diagnostic tool MB991958. Refer to "How to
connect SWS monitor P.54B-13."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to GROUP 54C,
Diagnosis P.54C-5).
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Go to Step 3.
NO : There is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Cope with Intermittent
Malfunction P.00-14).
Page 31 of 1500

DIAGNOSTIC TROUBLE CODE PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-31
STEP 3. Use diagnostic tool MB991958 to select "ECU
COMM Check" on the SWS monitor display.
Check the following ECUs:
Column-ECU
ETACS-ECU
Connect special tool MB991910 before connecting special
tool MB991812. Be sure to connect special tool MB991806
after turning on special tool MB991824.
(1) Connect the SWS monitor. Refer to "How to connect SWS
monitor P.54B-13."
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Operate diagnostic tool MB991958 according to the
procedure below to display "ECU COMM Check."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."
(4) DIAGNOSTIC TOOL MB991958 should show "OK" on the
"ECU COMM Check" menus for both the "COLUMN ECU"
and the "ETACS ECU" menus.
Q: Are "OK" displayed for both the "COLUMN ECU" and
"ETACS ECU" menus?
"OK" are displayed for all the items : It is determined that
there is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Cope with Intermittent
Malfunction P.00-14).
"NG" is displayed for the "COLUMN ECU" menu : Refer
to Inspection Procedure A-2 "Communication with the
column switch (column-ECU) is not possible
P.54B-68."
"NG" is displayed for the "ETACS ECU" menu : Refer to
Inspection Procedure A-3 "Communication with the
ETACS-ECU is not possible P.54B-74."
Page 33 of 1500

DIAGNOSTIC TROUBLE CODE PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-33
STEP 1. Using diagnostic tool MB991958, diagnose the
CAN bus line.
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 diagnostic tool MB991958. Refer to "How to
connect SWS monitor P.54B-13."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 2.
NO : Repair the CAN bus line (Refer to GROUP 54C,
Diagnosis P.54C-5).
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Erase the DTC.
(2) Turn the ignition switch to the "ON" position.
(3) Check if the DTC is set.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Go to Step 3.
NO : There is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Cope with Intermittent
Malfunction P.00-14).