Page 110 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-110
STEP 5. 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
Vehicle speed: 8 km/h (5 mph) or more
(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 are open, the system cannot be checked
correctly.
Q: Does diagnostic tool MB991958 display the items "IG
SW (IG1)", "FRONT DOOR SW" and "BUZZER" as
normal condition?
Normal conditions are displayed for all the items : Go to
St e p 6 .
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 "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 "BUZZER" :
Replace the ETACS-ECU. The ignition key reminder
tone alarm function should now work normally. ITEM NO. ITEM NAME NORMAL
CONDITION
ITEM 30 IG SW (IG1) ON
ITEM 32 FRONT DOOR SW ON
ITEM 43 BUZZER ON
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
Page 129 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-129
INSPECTION PROCEDURE C-2: Central Door Locking System: Some Doors do not Lock or Unlock.
.
CIRCUIT OPERATION
The ETACS-ECU operates the central door lock
system according to the following signals:
Front door lock actuator switch
Door lock key cylinder switch
Door lock switch, which is incorporated in the
power window main switch or front power win-
dow sub switch
The ETACS-ECU locks or unlocks all the doors
(except liftgate and glass hatch lock) by operating
the central door lock relay (incorporated in the
ECU) in response to input signals.
Page 143 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-143
INSPECTION PROCEDURE C-4: Central Door Locking System: All the Doors do not Lock or Unlock
with just the Door Lock Key Cylinder Key Operation.
.
TECHNICAL DESCRIPTION (COMMENT)
The door lock key cylinder switch or the ETACS-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
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
Check the input signal (by using the pulse check mode of
the monitor).
Check the input signals from the door lock key cylinder switch.
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 the special tool. Refer to "How to connect SWS
monitor P.54B-13."
(2) When the doors are locked and unlocked by using the
driver's door lock key cylinder, check that diagnostic tool
MB991958 sounds.
(3) Operate diagnostic tool MB991958 according to the
procedure below to display "Pulse check."
a. Select "Interactive Diagnosis."
b. Select "System Select."
c. Select "SWS."
d. Select "Pulse Checking."
Q: When the doors are locked and unlocked by using the
driver's door lock key cylinder, does diagnostic tool
MB991958 sound?
YES : Replace the ETACS-ECU. Check that all the doors
should be locked and unlocked by using driver door
lock key cylinder switch.
NO : Refer to Inspection Procedure N-4 "ETACS-ECU
does not receive any signal from the door lock key
cylinder switch P.54B-446."