Page 226 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-226
INSPECTION PROCEDURE G-1: Windshield Wiper and Washer: The windshield wiper do not work at
all.
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."
.
CIRCUIT OPERATION
The windshield wiper and washer switch sends a
signal through the column-ECU (incorporated in
the column switch) to the front-ECU. If the col-
umn-ECU sends a windshield wiper and washer
switch "ON" signal to the front-ECU, the
front-ECU turns on the relay (incorporated in the
front-ECU), thus causing the windshield wiper
and washer motor to be turned on.
If the SWS communication line is defective, the
front-ECU operates windshield wiper motor by
using the other communication lines (wiper
backup circuit) instead of that line. In this case,
the windshield wiper works at low speed regard-
less of the windshield wiper and washer switch
positions ("LO" or "HIGH").
.
TECHNICAL DESCRIPTION (COMMENT)
If the windshield wiper does not work at all, the wind-
shield wiper motor, column switch (windshield wiper
and washer switch) or the front-ECU may be defec-
tive.
.
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 column switch may be defective
The front-ECU may be defective
Page 230 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-230
STEP 4. Check the windshield wiper motor.
(1) Disconnect windshield wiper motor connector A-03.
(2) Connect a battery to the windshield wiper motor as shown.
Then check that the windshield wiper motor operates
normally at high and low speeds.
Q: Does the windshield wiper motor operate normally?
YES : Go to Step 5.
NO : Replace the windshield wiper motor. Verify that the
windshield wiper works normally.
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 238 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-238
STEP 2. Check windshield wiper motor connector A-03 for
loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Is windshield wiper motor connector A-03 in good
condition?
YES : Go to Step 3.
NO : Repair or replace the damaged component(s). Refer
to GROUP 00E, Harness Connector Inspection
P.00E-2. Verify that the windshield wiper operates
normally when the windshield wiper switch is moved
to each position.
STEP 3. Check the windshield wiper motor.
(1) Disconnect windshield wiper motor connector A-03.
(2) Connect a battery to the windshield wiper motor as shown.
Then check the windshield wiper motor operates normally
at high and low speeds.
Q: Does the windshield wiper motor operate normally?
YES : Go to Step 4.
NO : Replace the windshield wiper motor. Verify that the
windshield wiper operates normally when the
windshield wiper switch is moved to each position.
Page 242 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-242
STEP 2. Check the windshield wiper motor.
(1) Disconnect windshield wiper motor connector A-03.
(2) Connect the vehicle battery to the windshield wiper motor
connector as shown, and operate the windshield wiper at
low speed. While the windshield wiper is working,
disconnect the battery at positions other than the
predetermined park position to stop the windshield wiper
motor.
(3) When the battery is connected as shown, the motor should
run at low speed, and then stop at the predetermined park
position.
Q: Does the windshield wiper motor operate normally?
YES : Go to Step 3.
NO : Replace the windshield wiper motor. The windshield
wiper should now stop at the predetermined park
position.
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
Page 248 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-248
INSPECTION PROCEDURE G-6: Windshield Wiper and Washer: The windshield intermittent wiper
interval is not changed according to the vehicle speed.
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 the windshield intermittent wiper interval does not
change according to the vehicle speed, the
ETACS-ECU or the front-ECU may be defective.
.
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 combination meter may be defective
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