Page 108 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-108
STEP 3. Using diagnostic tool MB991958, read the
combination meter diagnostic trouble code.
Check whether the combination meter-related DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check whether the combination meter-related DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Diagnose the combination meter (Refer to GROUP
54A, Diagnostic trouble code chart P.54A-48).
NO : Go to Step 4.
Page 113 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-113
STEP 2. Using diagnostic tool MB991958, diagnose the
CAN bus line.
To prevent damage to diagnostic tool MB991958, always
turn the ignition switch to the "LOCK" (OFF) position
before connecting or disconnecting diagnostic tool
MB991958.
(1) Connect diagnostic tool MB991958. Refer to "How to
connect SWS monitor P.54B-13."
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?
YES : Go to Step 3.
NO : Repair the CAN bus line (Refer to GROUP 54C,
Diagnosis P.54C-13).
STEP 3. Using diagnostic tool MB991958, read the multi
center display diagnostic trouble code.
Check that a multi center display DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the multi center display DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the DTC set?
YES : Diagnose the multi center display unit (Refer to
GROUP 54A, Diagnosis P.54A-254).
NO : Go to Step 4.
Page 117 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-117
STEP 2. Check whether the turn-signal lamps illuminate.
When the turn-signal lamp switch or the hazard warning lamp
switch is operated, check that the turn-signal lamps flash.
Q: Are the turn-signal lamps in good condition?
YES : Go to Step 3.
NO : First, repair the turn-signal lamp(s). Refer to
Inspection Procedure I-3 "One of the turn-signal
lamps does not illuminate P.54B-316."
STEP 3. Use diagnostic tool MB991958 to select "ECU
COMM Check" on the SWS monitor display.
Check the following ECUs:
ETACS-ECU
Column-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."
1. Select "Interactive Diagnosis."
2. Select "System Select."
3. Select "SWS."
4. Select "SWS MONITOR."
5. Select "ECU COMM Check."
(4) diagnostic tool MB991958 should show "OK" on the "ECU
COMM Check" menus for both the "ETACS ECU" and the
"COLUMN ECU" menus.
Q: Is "OK" displayed for both the "ETACS ECU" and
"COLUMN ECU" menus?
"OK" is displayed for all the items : Go to Step 4.
"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 "ETACS ECU" menu : Refer to
Inspection Procedure A-3 "Communication with the
ETACS-ECU is not possible P.54B-74."
"NG" is displayed for all the items : Refer to Inspection
Procedure A-3 "Communication with the ETACS-ECU
is not possible P.54B-74."
Page 118 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-118
STEP 4. Check the input signal by using "FUNCTION
DIAG." menu of the SWS monitor.
Check the input signals from the following switches:
Ignition switch: ON
Driver’s door: Open
All door: Closed
(1) Operate diagnostic tool MB991958 according to the
procedure below to display "OTHER ALARM"
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "Function Diag."
f. Select "BUZZER."
g. Select "OTHER ALARM"
(2) Check that normal conditions are displayed for the items
described in the table below.
NOTE: The diagnostic tool MB991958 display changes
when the driver's or the front passenger's door is opened. If
any of the doors is open, the system cannot be checked
correctly.
Q: Does diagnostic tool MB991958 display the items "IG
SW (IG1)" and "BUZZER" as normal condition?
Normal conditions are displayed for all the items :
Replace the ETACS-ECU. Check that the turn-signal
lamp buzzer function works normally.
Normal condition is not displayed for "IG SW (IG1)" :
Refer to Inspection Procedure M-2 "ETACS-ECU
does not receive any signal from the ignition switch
(IG1) P.54B-408."
Normal condition is not displayed for "BUZZER" :
Replace the ETACS-ECU. Check that the turn-signal
lamp buzzer function works normally.
CENTRAL DOOR LOCKING SYSTEM
GENERAL DESCRIPTION CONCERNING CENTRAL DOOR LOCKING SYSTEMM1549021100271
The following ECUs affect the functions and control
of the central door locking system.ITEM NO. ITEM NAME NORMAL
CONDITION
ITEM 30 IG SW (IG1) ON
ITEM 43 BUZZER ON
FUNCTIONCONTROL ECU
Central door locking system ETACS-ECU
Forgotten key prevention function ETACS-ECU
Page 119 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-119
CENTRAL DOOR LOCKING SYSTEM
.
DOOR UNLOCKING BY OPERATING THE
DRIVER’S DOOR LOCK KEY CYLINDER
When the ignition key is inserted in the driver’s door lock key
cylinder and turned anti-clockwise to unlock the driver’s door,
the ETACS-ECU operates its door unlock relay and passes a
current through the door lock actuator of the driver’s door for
0.25 seconds to unlock only the driver’s door.
When the ignition key is turned anti-clockwise again, the
ETACS-ECU operates its door unlock relay and passes a cur-
rent through the door lock actuators of all doors for 0.25 sec-
onds and to unlock all doors.
NOTE: Vehicles with a multi center display (middle grade type)
can be customized so that a single unlock operation will unlock
all doors. Refer to P.54B-486.
.
DOOR LOCKING OR UNLOCKING BY
OPERATING THE DRIVER’S OR FRONT
PASSENGER’S DOOR LOCK SWITCH
When the door is locked by the driver’s or front passenger’s
door lock switch, the ETACS-ECU operates its door lock relay
and passes a current through the door lock actuators of all
doors for 0.25 seconds to lock all doors.
When the door is unlocked by the driver’s or front passenger's
door lock switch, the ETACS-ECU operates its door unlock
relay and passes a current through the door lock actuators of
all doors for 0.25 seconds to unlock all doors.
When the door is locked and unlocked by driver’s or front pas-
senger's door lock switch consecutively, the ETACS-ECU oper-
ates its door lock relay and passes a current through the door
lock actuators of all doors for 0.25 seconds to lock all doors.
Then, the ETACS-ECU operates its door unlock relay and
passes a current through the door lock actuators of all doors for
0.25 seconds to unlock all doors. Due to this, there may be a
time lag between the driver’s or front passenger's door lock
switch actuation and the time when all doors are unlocked.
Page 120 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-120
FORGOTTEN KEY PREVENTION FUNCTION
If the driver's door is locked while it is open
If the driver's door is locked while it is open and when
the key is still in the ignition key cylinder, approxi-
mately 0.3 second later the ETACS-ECU activates
the unlock relay output for 0.25 second to prevent
the door from being locked with the key inside the
vehicle.In addition, if locking the door was not prevented, a
re-try current is sent (an unlock relay output ON is
sent for 0.25 second up to 5 times including the first
attempt).
NOTE: The dotted line indicates that the system is
trying to turn on the unlock relay if the door cannot be
unlocked.
If the front passenger's door is open when it is locked with the driver's door switch
Page 121 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-121
If the passenger's door or driver's door are locked
while the passenger's door is open and when the key
is still in the ignition key cylinder, approximately 0.3
second later the ETACS-ECU activates the unlock
relay output for 0.25 second to prevent the door from
being locked with the key inside the vehicle.In addition, if locking the door was not prevented, a
re-try current is sent (an unlock relay output ON is
sent for 0.25 second up to 5 times including the first
attempt).
NOTE: The dotted line indicates that the system is
trying to turn on the unlock relay if the door cannot be
unlocked.
Page 122 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-122
INSPECTION PROCEDURE C-1: Central Door Locking System: The Central Door Locking System
does not Work at all.
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
The ETACS-ECU controls the central door lock
system, locking or unlocking all the doors by acti-
vating the central door lock relay (built into the
ETACS-ECU). The ETACS-ECU uses inputs from
the following components:
Front door lock actuator
Front door lock key cylinder switch
Door lock switch, which is incorporated in the
power window main switch or front power win-
dow sub switch
.
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 ETACS-ECU may be defective