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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-273
INSPECTION PROCEDURE H-5: Headlamp and Taillamp: Headlamps do not illuminate when the
lighting switch is at "TAIL," and "PASSING" position, but illuminate at low-beam when the switch is at
"HEAD" position. At this position, the headlamps cannot be changed to high beam by operating the
dimmer 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 headlamps illuminate at low-beam regardless
of the lighting switch positions, the headlamp opera-
tion is in fail-safe mode.
.
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 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
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-274
Use Diagnostic Tool MB991958 to select "ECU COMM
Check" on the SWS monitor display.
Check the following ECUs:
ETACS-ECU
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 "LOCK" (OFF) position.
(3) Operate Diagnostic Tool MB991958 according to the
procedure below to display "ECU COMM Check."
a. Select "System select."
b. Select "SWS."
c. Select "SWS MONITOR."
d. Select "ECU COMM Check."
(4) Diagnostic Tool MB991958 should show "OK" on the "ECU
COMM Check" menus for the "ETACS ECU", "COLUMN
ECU" and "FRONT ECU" menus.
Q: Is "OK" displayed for both the "ETACS ECU", "COLUMN
ECU" and "FRONT ECU" menus?
"OK" is displayed for all the items : Replace the
front-ECU. Verify that the headlamps and the
taillamps illuminate normally.
"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."
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-275
INSPECTION PROCEDURE H-6: Headlamp and Taillamp: The front park lamps, taillamps or the
licence plate lamps do not illuminate.
.
TECHNICAL DESCRIPTION (COMMENT)
If the front park lamps, taillamps or the licence plate
lamp do not illuminate, their bulb may be defective.
.
TROUBLESHOOTING HINTS
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
The front park lamp bulb may be defective
The stop/taillamp bulb may be defective
The licence plate lamp bulb may be defective
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector
.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-276
DIAGNOSIS
Required Special Tool:
MB991223: Harness Set
STEP 1. Check the operation of each lamp.
Q: Which lamp does not illuminate?
front park lamp (LH), taillamp (LH), and licence plate
lamp : Go to Step 2.
front park lamp (RH), taillamp (RH) : Go to Step 4.
taillamp (LH) and licence plate lamp : Go to Step 6.
taillamp (LH) : Go to Step 8.
taillamp (RH) : Go to Step 13.
front park lamp (LH) : Go to Step 19.
front park lamp (RH) : Go to Step 25.
licence plate lamp : Go to Step 31.
All lamps : Refer to Inspection Procedure H-1 "The
taillamps do not illuminate normally P.54B-260."
STEP 2. Check front-ECU connector A-11X for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is front-ECU connector A-11X 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. The front park lamp (LH), taillamp (LH), and
the licence plate lamp should illuminate normally.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-277
STEP 3. Check the wiring harness between intermediate
connector C-25 (terminal 10) and front-ECU connector
A-11X (terminal 4).
Q: Is the wiring harness between intermediate connector
C-25 (terminal 10) and front-ECU connector A-11X
(terminal 4) 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 front
parking lamp (LH), taillamp (LH),and the licence plate
lamp should illuminate normally.
STEP 4. Check intermediate connector C-25 and front-ECU
connector A-11X for loose, corroded or damaged
terminals, or terminals pushed back in the connector.
Q: Are intermediate connector C-25 and front-ECU
connector A-11X 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. The front parking lamp (RH), and the
taillamp (RH) should illuminate normally.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-278
STEP 5. Check the wiring harness between intermediate
connector C-25 (terminal 8) and front-ECU connector
A-11X (terminal 4).
Q: Is the wiring harness between intermediate connector
C-25 (terminal 8) and front-ECU connector A-11X
(terminal 4) 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 front
parking lamp (RH), and the taillamp (RH) should
illuminate normally.
STEP 6. Check intermediate connector C-25 for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is intermediate connector C-25 in good condition?
YES : Go to Step 7.
NO : Repair or replace the damaged component(s). Refer
to GROUP 00E, Harness Connector Inspection
P.00E-2. The taillamp (LH) and the licence plate lamp
should illuminate normally.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-279
STEP 7. Check the wiring harness between intermediate
connector C-25 (terminal 10) and rear combination lamp
(LH) connector F-09 (terminal 4).
NOTE: Check intermediate connector C-25 for loose, corroded,
or damaged terminals, or terminals pushed back in the connec-
tor. If intermediate connector C-25 is damaged, repair or
replace the damaged component(s) as described in GROUP
00E, Harness Connector Inspection P.00E-2.
Q: Is the wiring harness between intermediate connector
C-25 (terminal 10) and rear combination lamp (LH)
connector F-09 (terminal 4) 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 taillamp
(LH) and the licence plate lamp should illuminate
normally.
STEP 8. Check rear combination lamp (LH) connector F-09
for loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Is rear combination lamp (LH) connector F-09 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. Check that the taillamp (LH) illuminates
normally.
STEP 9. Check the stop/taillamp bulb (LH).
(1) Remove the stop/taillamp bulb (LH).
(2) Verify that the stop/taillamp bulb (LH) is not damaged or
burned out.
Q: Is the stop/taillamp bulb (LH) in good condition?
YES : Go to Step 10.
NO : Replace the stop/taillamp bulb (LH). Verify that the
taillamp (LH) illuminates normally.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-280
STEP 10. Check the ground circuit to the rear combination
lamp (LH). Measure the resistance at rear combination
lamp (LH) connector F-09.
(1) Disconnect rear combination lamp (LH) connector F-09 and
measure the resistance available at the wiring harness side
of the connector.
(2) Measure the resistance value between terminal 2 and
ground.
The resistance should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES : Go to Step 12.
NO : Go to Step 11.
STEP 11. Check the wiring harness between rear
combination lamp (LH) connector F-09 (terminal 2) and
ground.
Q: Is the wiring harness between rear combination lamp
(LH) connector F-09 (terminal 2) and ground in good
condition?
YES : Replace the rear combination lamp socket (LH).
Verify that the taillamp (LH) illuminates normally.
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 taillamp (LH) illuminates normally.