Page 251 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-251
INSPECTION PROCEDURE G-7: Windshield Wiper and Washer: The windshield washer does not
work.
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 washer switch sends a signal
through the column-ECU (incorporated in the column
switch) to the front-ECU. If the column-ECU sends a
windshield washer switch "ON" signal to the
front-ECU, the front-ECU turns on the relay (incorpo-
rated in the front-ECU), thus causing the windshield
washer motor to be turned on.
.
TECHNICAL DESCRIPTION (COMMENT)
If the windshield washer does not work normally, the
windshield washer motor, the column switch (wind-
shield 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
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector
The windshield washer motor may be defective
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
STEP 1. Verify the windshield wiper operation.
Q: Does the windshield wiper operate normally?
YES : Go to Step 2.
NO : Refer to Inspection Procedure G-1 "The windshield
wiper do not work at all P.54B-226."
Page 252 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-252
STEP 2. 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 3.
"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 253 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-253
STEP 3. Check the input signal by using "FUNCTION
DIAG." menu of the SWS monitor.
Check the input signals from the following switches:
Ignition switch: ACC
Windshield washer switch: ON
(1) Operate the Diagnostic Tool MB991958 according to the
procedure below to display "F.WIPER WASH."
a. Select "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "WIPER."
g. Select "F.WIPER WASH."
(2) Check that normal conditions are displayed for the items
described in the table below.
Q: Are normal conditions displayed for "FRONT
WASH.SW" and "FRONT ECU ACK"?
Normal conditions displayed for all the items : Go to
St e p 4 .
Normal condition is not displayed for the "FRONT
WASH.SW" : Replace the column switch. Verify that the
windshield washer works normally.
Normal condition is not displayed for the "FRONT ECU
ACK" : Replace the front-ECU. Verify that the windshield
washer works normally.
STEP 4. Check windshield washer motor connector A-29
for loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Is windshield washer motor connector A-29 in good
condition?
YES : Go to Step 5.
NO : Repair or replace the damaged component(s). Refer
to GROUP 00E, Harness Connector Inspection
P.00E-2. Verify that the windshield washer works
normally. ITEM NO. ITEM NAME NORMAL
CONDITION
ITEM 09 FRONT WASH.SW ON
ITEM 70 FRONT ECU ACK NORMAL ACK or
HI-BEAM ACK
Page 255 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-255
STEP 6. Check the ground circuit to the windshield washer
motor. Measure the resistance at the windshield washer
motor connector A-29.
(1) Disconnect windshield washer motor connector A-29 and
measure the resistance available at the wiring harness side
of the connector.
(2) Measure the resistance value between terminal 1 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.
STEP 7. Check the wiring harness between windshield
washer motor connector A-29 (terminal 1) and ground.
Q: Is the wiring harness between windshield washer motor
connector A-29 (terminal 1) and ground 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. Verify that
the windshield washer works normally.
STEP 8. Check front-ECU connector A-12X for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is front-ECU connector A-12X in good condition?
YES : Go to Step 9.
NO : Repair or replace the damaged component(s). Refer
to GROUP 00E, Harness Connector Inspection
P.00E-2. Verify that the windshield washer works
normally.
Page 256 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-256
STEP 9. Check the wiring harness between windshield
washer motor connector A-29 (terminal 2) and front-ECU
connector A-12X (terminal 31).
Q: Is the wiring harness between windshield washer motor
connector A-29 (terminal 2) and front-ECU connector
A-12X (terminal 31) 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. Verify that
the windshield washer works normally.
Page 257 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-257
HEADLAMP AND TAILLAMP
GENERAL DESCRIPTION CONCERNING THE HEADLAMPS AND TAILLAMPSM1549021300264
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80The following ECUs affect the functions and control
of the headlamps and the taillamps.
FUNCTION CONTROL ECU
Taillamps Front-ECU, column switch
Headlamps ETACS-ECU, front-ECU, column switch
High-beam indicator lamp ETACS-ECU, column switch
Headlamp automatic-shutoff function ETACS-ECU, front-ECU, column switch
Dimmer automatic reset function Front-ECU, column switch
Page 258 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-258
Taillamps and headlamps illumination
.
Taillamps
If the column switch sends a taillamp switch "ON" signal to the
front-ECU, the front-ECU turns on its taillamp relay, causing the
taillamps to illuminate.
NOTE: This description covers the taillamps only. In actual driv-
ing, the taillamps may be turned off due to the headlamp auto-
matic shut-off function. For the details of the headlamp
automatic shut-off function, refer to .
.
Headlamps
If the column switch sends a headlamp switch "ON"
signal to the front-ECU, the front-ECU turns on its
headlamp relay (LOW), causing the low-beam
headlamps to illuminate. If the dimmer switch is
turned on while the headlamp relay (LOW) is on, the
front-ECU turns on the headlamp relay (HIGH),
causing the high-beam headlamps to illuminate.NOTE: This description covers the headlamps only.
In actual driving, the headlamps may be turned off
due to the headlamp automatic shut-off function. For
the details of the headlamp automatic shut-off func-
tion, refer to .
High-beam indicator lamp
At the same time that the high-beams are illuminated, the
ETACS-ECU sends a signal to illuminate the high beam indica-
tor via the CAN bus line. The combination meter receives the
transmitted signal and turns the high-beam indicator on and off.
Page 260 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-260
INSPECTION PROCEDURE H-1: Headlamp and Taillamp: The taillamps do not illuminate normally.
NOTE: This troubleshooting procedure requires the
use of Diagnostic Tool MB991958 and SWS monitor
kit MB991813. For details on how to connect the
SWS monitor, refer to "How to connect SWS monitor
P.54B-13."
.
CIRCUIT OPERATION
When the lighting switch is set to "TAIL" position, the
"TAIL" signal is sent through the column-ECU (incor-
porated in the column switch) to the front-ECU. If the
front-ECU receives the "TAIL" signal through the col-
umn-ECU, the front-ECU turns on the taillamp relay
(incorporated in the front-ECU), thus causing the
taillamps to illuminate.
.
TECHNICAL DESCRIPTION (COMMENT)
If the taillamps do not illuminate normally, the column
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 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