Page 59 of 1500

SYMPTOM CHART
SIMPLIFIED WIRING SYSTEM (SWS)54B-59
Headlamp and
taillampGeneral description concerning the headlamp and
taillampP.54B-257
The taillights do not illuminate normally. H-1
P.54B-260
The headlamps (low-beam) do not illuminate
normally.H-2
P.54B-264
The headlamps (high-beam) do not illuminate
normally.H-3
P.54B-268
When the passing switch is turned "ON," the
headlamps (low-beam or high-beam) do not
illuminate.H-4
P.54B-271
Headlights 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.H-5
P.54B-273
The taillamps, the position lamps, front parking
lamps or the license plate lamp do not illuminate.H-6
P.54B-275
One of the headlamps does not illuminate. H-7
P.54B-290
The high-beam indicator lamp does not illuminate. H-8
P.54B-301
Headlamp automatic shutoff function does not
work normally.H-9
P.54B-305
Headlamp dimmer switch automatic resetting
function does not work normally.H-10
P.54B-308
Flasher timer General description concerning the flasher timer
P.54B-309
Turn-signal lamps do not flash when the
turn-signal lamp switch is turned on.I-1
P.54B-310
Hazard warning lamps do not flash when the
hazard warning lamp switch is turned on.I-2
P.54B-314
One of the turn-signal lamps does not illuminate. I-3
P.54B-316
The turn-signal lamp indicator does not illuminate
normally.I-4
P.54B-335
Fog lamp General description concerning the fog lamps
P.54B-339
Fog lamps do not illuminate when the fog lamp
switch is turned on.J-1
P.54B-340
Fog lamps do not go out when the headlamps
(low-beam) are turned off while the fog lamps are
on.J-2
P.54B-345
One of the fog lamps does not illuminate. J-3
P.54B-345
The fog lamp indicator does not illuminate
normally.J-4
P.54B-350 SYSTEM SYMPTOM INSPECTION
PROCEDUREREFERENCE
PA G E
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 259 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-259
Headlamp automatic-shutdown function
Even if the lighting switch (taillamps switch or headlamp switch)
is ON, the headlamps (including the taillamps) will automati-
cally go off in the following conditions to prevent the battery
from discharging as a result of forgetting to turn off lamps.
If the ignition key is turned from "ON" to "LOCK" (OFF) or
"ACC" position with the lighting switch turned ON, and this
state continues for three minutes, the headlamps will automati-
cally be turned off. If the driver's seat door is opened during
these three minutes, the headlamps will go off one second
later.
NOTE: The headlamp automatic-shutoff function can be cus-
tomized on vehicles equipped with a multi center display (mid-
dle grade type). Refer to P.54B-486.
Dimmer automatic reset function
If the headlamp switch is turned off while the high-beam
headlamps are on, the dimmer switch will be reset. Because of
this, the headlamps will illuminate at low beam the next time
that they are turned on. The dimmer switch will be also reset if
the dimmer switch is turned on unintentionally while the pass-
ing switch is operated.
Page 264 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-264
STEP 5. Check the wiring harness between front-ECU
connector A-11X (terminal 7) and the battery.
Q: Is the wiring harness between front-ECU connector
A-11X (terminal 7) and the battery 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 taillamps illuminate normally.
INSPECTION PROCEDURE H-2: Headlamp and Taillamp: The headlamps (low-beam) 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 use the SWS
monitor, refer to "How to connect SWS monitor
P.54B-13."
.
CIRCUIT OPERATION
When the lighting switch is set to "HEAD" posi-
tion, the "HEAD" signal is sent through the col-
umn-ECU (incorporated in the column switch) to
the front-ECU. If the front-ECU receives the
"HEAD" signal through the column-ECU, the
front-ECU turns on the headlamp relay (incorpo-
rated in the front-ECU), thus causing the
headlamps to illuminate. The headlamps always
illuminate at low-beam by the headlamp dimmer
switch automatic resetting function.
If the SWS communication line is defective, the
front-ECU operates the headlamps by using the
other communication lines (headlamp backup cir-
cuit) instead of that line.
.
TECHNICAL DESCRIPTION (COMMENT)
If the headlamps (low-beam) do not illuminate nor-
mally, 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
Page 308 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-308
(IG1) P.54B-408."
Normal condition is not displayed for "FRONT DOOR
SW" : Refer to Inspection Procedure M-4 "ETACS-ECU
does not receive any signal from the front door
switches P.54B-413."
Normal condition is not displayed for "H/L AUTO-CUT" :
Replace the front-ECU. Check that the headlamp
automatic shutdown function works normally.
INSPECTION PROCEDURE H-10: Headlamp and Taillamp: Headlamp dimmer switch automatic
resetting function does not work normally.
.
CIRCUIT OPERATION
The headlamp dimmer switch automatic resetting
function is controlled by the front-ECU.
.
TECHNICAL DESCRIPTION (COMMENT)
If the headlamp dimmer switch automatic resetting
function does not work normally, the front-ECU may
be defective.
.
TROUBLESHOOTING HINT
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
The front-ECU may be defective
DIAGNOSIS
Replace the front-ECU.
Check that the headlamp dimmer switch automatic resetting
function works normally.
Page 756 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-55
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Connect diagnostic tool to the data link connector
(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 check result satisfactory?
YES : There is an intermittent malfunction such as poor
engaged connector(s) or open circuit (Refer to
GROUP 00, How to Use Troubleshooting/Inspection
Service Points
How to Cope with Intermittent
Malfunctions P.00-14.)
NO : Replace the A/C-ECU. On completion, check that the
DTC is not reset.
Page 759 of 1500

AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-58
STEP 3. Using diagnostic tool , check for any diagnostic
trouble code.
Check if a DTC, which relates to CAN communication-linked
systems below, is set.
Combination meter
DTC indicating a time-out error related to the engine or
automatic transmission control system
ETACS-ECU
DTC indicating a time-out error related to the engine or
automatic transmission control system
(1) Turn the ignition switch to the "ON" position.
(2) Check for a DTC related to the relevant system.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : Go to Step 5.
NO : Go to Step 4.
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : A poor connection, open circuit or other intermittent
malfunction is present in the lines between the
Electronic control unit and the A/C-ECU (Refer to
GROUP 00E, Harness Connector Inspection
P.00E-2.)
NO : Replace the Electronic control unit. On completion,
check that the DTC is not reset.
Page 760 of 1500
AUTO A/C DIAGNOSIS
HEATER, AIR CONDITIONING AND VENTILATION55-59
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the check result satisfactory?
YES : A poor connection, open circuit or other intermittent
malfunction is present in the lines between the
Electronic control unit and the A/C-ECU (Refer to
GROUP 00E, Harness Connector Inspection
P.00E-2.)
NO : Replace the A/C-ECU. On completion, check that the
DTC is not reset.