Page 227 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-227
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: Test Probe Harness
Page 228 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-228
STEP 1. Use Diagnostic Tool MB991958 to select "ECU
COMM Check" on the SWS monitor display.
Check the following ECUs:
Column-ECU
Front-ECU
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958. Connect special tool MB991910 before con-
necting special tool MB991812. Be sure to connect special
tool MB991806 after turning on special tool MB991824.
(1) Connect the special tool. Refer to "How to connect SWS
monitor P.54B-13."
(2) Turn the ignition switch to the "ON" 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 "FRONT ECU" menus.
Q: Is "OK" displayed for the "COLUMN ECU" and "FRONT
ECU" menu?
"OK" is displayed for all the items : Go to Step 2.
"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."
Page 234 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-234
INSPECTION PROCEDURE G-2: Windshield Wiper and Washer: The windshield wipers do not work
when the windshield wiper switch is at "INT" or "MIST" position or the windshield washer switch is at
"ON" position. However, the wipers work at low speed when the windshield wiper switch is at "LO" or
"HI."
NOTE: This troubleshooting procedure requires use
of Diagnostic Tool MB991958 and SWS monitor kit
MB991813. For details on how to use the SWS mon-
itor, refer to "How to connect SWS monitor
P.54B-13."
.
TECHNICAL DESCRIPTION (COMMENT)
This system may be at fail-safe mode as the SWS
communication line is defective.
If the system cannot receive any signal from the col-
umn switch (windshield wiper and washer switch)
due to a open circuit in the SWS communication line
or other reasons, the system will enter the fail-safe
mode when the ignition switch is at the "ACC" posi-
tion.
.
TROUBLESHOOTING HINTS
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector
The column switch may be defective
The front-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
MB991813: SWS Monitor Kit
MB991806: SWS Monitor Cartridge
MB991812: SWS Monitor Harness (For Column-ECU)
MB991822: Test Probe Harness
Page 235 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-235
Use Diagnostic Tool MB991958 to select "ECU COMM
Check" on the SWS monitor display.
Check the following ECUs:
Column-ECU
Front-ECU
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958. Connect special tool MB991910 before con-
necting special tool MB991812. Be sure to connect special
tool MB991806 after turning on special tool MB991824.
(1) Connect the special tool. Refer to "How to connect SWS
monitor P.54B-13."
(2) Turn the ignition switch to the "ON" 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 "FRONT ECU" menus.
Q: Is "OK" displayed for the "COLUMN ECU" and "FRONT
ECU" menu?
"OK" is displayed for all the items : Replace the
front-ECU. Verify that the windshield wiper works
normally.
"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."
Page 236 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-236
INSPECTION PROCEDURE G-3: Windshield Wiper and Washer: All of the windshield wiper switch
positions are defective.
NOTE: This troubleshooting procedure requires use
of Diagnostic Tool MB991958 and SWS monitor kit
MB991813. For details on how to use the SWS mon-
itor, refer to "How to connect SWS monitor
P.54B-13."
.
TECHNICAL DESCRIPTION (COMMENT)
If either of the windshield wiper switch positions is
defective, the windshield wiper motor, column switch
(windshield wiper and washer switch) or the
front-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 wiper motor may be defective
The front-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
MB991813: SWS Monitor Kit
MB991806: SWS Monitor Cartridge
MB991812: SWS Monitor Harness (For Column-ECU)
MB991822: Test Probe Harness
Page 237 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-237
STEP 1. Check the input signal by using "DATA LIST"
menu of the SWS monitor.
Turn the ignition switch to the ACC position before checking
input signals from the windshield wiper 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. Connect special tool MB991910 before con-
necting special tool MB991812. Be sure to connect special
tool MB991806 after turning on special tool MB991824.
(1) Connect the special tool. Refer to "How to connect SWS
monitor P.54B-13."
(2) Operate Diagnostic Tool MB991958 according to the
procedure below to display "COLUMN ECU."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Data List."
f. Select "COLUMN ECU."
(3) Check that normal conditions are displayed for the items
described in the table below.
Q: Are normal conditions displayed for "INT WIPER SW",
"LO WIPER SW", "HI WIPER SW" and "MIST WIPER
SW"?
YES : Go to Step 2.
NO : Refer to Inspection Procedure M-6 "ETACS-ECU
does not receive any signal from the windshield mist
wiper switch P.54B-423." ITEM NO. ITEM NAME NORMAL
CONDITION
ITEM 05 INT WIPER SW ON
ITEM 06 LO WIPER SW ON
ITEM 07 HI WIPER SW ON
ITEM 08 MIST WIPER SW ON
Page 246 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-246
INSPECTION PROCEDURE G-5: Windshield Wiper and Washer: The windshield intermittent wiper
interval cannot be adjusted by using the variable intermittent wiper control switch.
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."
.
TECHNICAL DESCRIPTION (COMMENT)
If the windshield intermittent wiper interval is not
changed by operating the windshield intermittent
wiper interval adjusting knob or according to the
vehicle speed, the column switch, the ETACS-ECU
or the front-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
The front-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
MB991813: SWS Monitor Kit
MB991806: SWS Monitor Cartridge
MB991812: SWS Monitor Harness (For Column-ECU)
MB991822: Test Probe Harness
Page 247 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-247
Check the input signal by using "DATA LIST" menu of the
SWS monitor.
Set each switch to the following condition to check input signals
from the variable intermittent wiper control switch:
Ignition switch: ACC
Windshield wiper switch: INT
To prevent damage to Diagnostic Tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting Diagnostic Tool
MB991958. Connect special tool MB991910 before con-
necting special tool MB991812. Be sure to connect special
tool MB991806 after turning on special tool MB991824.
(1) Connect the special tool. Refer to "How to connect SWS
monitor P.54B-13."
(2) Operate Diagnostic Tool MB991958 according to the
procedure below to display "F.WIPER INT."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "WIPER."
g . S e l e c t " F. W I P E R I N T. "
(3) Check that normal conditions are displayed for the items
described in the table below.
NOTE: Also check that the windshield wiper interval
changes smoothly when the variable intermittent wiper con-
trol switch is rotated from "SLOW" to "FAST" position.
Q: Does the value change within the normal range when
the windshield intermittent wiper interval adjusting
knob is rotated?
YES : Replace the front-ECU. Check that the windshield
intermittent wiper interval changes according to the
vehicle speed or while the windshield intermittent
wiper interval adjusting knob is rotated.
NO : Refer to Inspection Procedure M-7 "ETACS-ECU
does not receive any signal from the variable
intermittent wiper control switch P.54B-426." ITEM NO. ITEM NAME NORMAL
CONDITION
ITEM 37 INT WIPER TIME 1.6
19.0 s