Page 393 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-393
STEP 5. Check the input signal (by using the pulse check
mode of the monitor).
Check the following switches and input signals:
Door switches
Interior lamp loaded signal
(1) 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."
(2) Check if diagnostic tool MB991958 sounds or not.
Q: When any door switch, interior lamp or the trunk lid
latch is operated, does diagnostic tool MB991958
sound?
Buzzer of diagnostic tool MB991958 sounds normally. :
Replace the ETACS-ECU. Verify that the dome lamp
illuminates normally.
When one of the doors is opened and closed,
diagnostic tool MB991958 does not sound : Refer to
Inspection Procedure N-3 "ETACS-ECU does not
receive any signal from any of the door switches
P.54B-440."
When one of the interior lamps is illuminated,
diagnostic tool MB991958 does not sound : Refer to
Inspection Procedure N-9 "ETACS-ECU does not
receive any interior lamp loaded signal P.54B-474." ITEM NAME CONDITION
interior lamp loaded
signalTurn on one of the interior lamps
door switch Open or close one of the doors
Page 394 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-394
INSPECTION PROCEDURE K-6: Interior Light: The door ajar indicator lamps do not illuminate or go
out 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
The combination meter receives the door switches
signals from the ETACS-ECU, and then controls the
door ajar indicator, based on these signals.
.
TECHNICAL DESCRIPTION (COMMENT)
If the door ajar indicator does not illuminate, connec-
tor(s), wiring harness in the CAN bus lines, the door
switches, the ETACS-ECU, or the combination meter
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 combination meter may be defective
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
MB991813: SWS Monitor Kit
MB991806: SWS Monitor Cartridge
MB991812: SWS Monitor Harness (For Column-ECU)
MB991822: Test Probe Harness
Page 398 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-398
INSPECTION PROCEDURE K-7: Interior Light: The seat belt warning lamp do not illuminate or go out
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
The combination meter and the ETACS-ECU illumi-
nates and flashes the seat belt warning lamp by
using the signal from the seat belt switch, the ignition
switch (IG1) and the vehicle speed signal.
.
TECHNICAL DESCRIPTION (COMMENT)
If the seat belt warning lamp does not illuminate or
flash correctly, connector(s), wiring harness in the
CAN bus lines, the door switches, the ETACS-ECU,
or the combination meter 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 combination meter may be defective
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
MB991813: SWS Monitor Kit
MB991806: SWS Monitor Cartridge
MB991812: SWS Monitor Harness (For Column-ECU)
MB991822: Test Probe Harness
Page 405 of 1500

INPUT SIGNAL PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-405
INPUT SIGNAL PROCEDURES
INSPECTION PROCEDURE M-1: ETACS-ECU does not receive any signal from the ignition switch
(ACC).
.
CIRCUIT OPERATION
The ETACS-ECU operates the following equipment
and function(s) according to signal from the ignition
switch (ACC):
Windshield wiper and washer
Interior lamp automatic shutoff function
The ETACS-ECU receives information on the ignition
switch condition (ACC) from the middle-grade multi
center display unit via CAN communication. If the
ignition switch (ACC) input signal is incorrect, refer to
the appropriate Diagnostic Trouble Code Chart
P.54B-25.
.
TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the equipment and func-
tion(s), which are described in "CIRCUIT OPERA-
TION", do not work normally.
.
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 414 of 1500

INPUT SIGNAL PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-414
CIRCUIT OPERATION
The ETACS-ECU operates the following functions or
systems according to signal from the front door
switches:
Light reminder tone alarm function
switch (RH)>
Door ajar warning buzzer
Forgotten key reminder
Power window timer function
Sunroof timer function
Keyless entry system
Timed locking mechanism
Headlamp automatic shutdown function
door switch (RH)>
Dome lamp
Interior lamp automatic-shutdown function
Ignition key hole illumination lamp
switch (RH)>
Door-ajar indicator lamp
.
TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the functions or systems
described in "CIRCUIT OPERATION" do not work
normally. If the signal is not normal, the front door
switches or the ETACS-ECU may be defective.
.
TROUBLESHOOTING HINTS
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
The front door switches may be defective
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 440 of 1500

INPUT SIGNAL PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-440
INSPECTION PROCEDURE N-3: ETACS-ECU does not receive any signal from any of the door
switches.
.
CIRCUIT OPERATION
The ETACS-ECU operates the following functions or
systems according to signal from the front or rear
door switches:
Light reminder tone alarm function
switch (RH)>
Door ajar warning buzzer
Ignition key reminder tone alarm
switches>
Power window timer function
switches>
Sunroof timer function
Headlamp automatic shutdown function
door switch (RH)>
Keyless entry system
Timer lock
Dome lamp
Interior lamp automatic-shutdown function
door switches>
Ignition key hole illumination lamp
switch (RH)>
Door-ajar indicator lamp
.
TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the functions or systems
described in "CIRCUIT OPERATION" do not work
normally. If the signal is not normal, the front or rear
door switches or the ETACS-ECU may be defective.
.
TROUBLESHOOTING HINTS
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
The front or rear door switches may be defective
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
Page 474 of 1500
INPUT SIGNAL PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-474
INSPECTION PROCEDURE N-9: ETACS-ECU does not receive any interior lamp loaded signal.
.
CIRCUIT OPERATION
The ETACS-ECU operates the following equipment
or functions by the interior lamp loaded signal:
Interior lamp automatic shut-down function
Dome lamp
Ignition key hole illumination lamp
.
TECHNICAL DESCRIPTION (COMMENT)
If the signal is not normal, the equipment or functions
described in "CIRCUIT OPERATION" do not work
normally.
.
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 475 of 1500

INPUT SIGNAL PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-475
DIAGNOSIS
Required Special Tool:
MB991223: Harness Set
STEP 1. Check ETACS-ECU connector C-219 for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is ETACS-ECU connector C-219 in good condition?
YES : Go to Step 2.
NO : Repair or replace the damaged component(s). Refer
to GROUP 00E, Harness Connector Inspection
P.00E-2. If the functions or equipment described in
"CIRCUIT OPERATION" work normally, the interior
lamp loaded signal should be normal.
STEP 2. Check the battery line of power supply circuit to
the ETACS-ECU. Measure the voltage at ETACS-ECU
connector C-219.
(1) Disconnect ETACS-ECU connector C-219 and measure the
voltage available at the junction block side of the connector.
(2) Measure the voltage between terminal 20 and ground.
The voltage should measure approximately 12 volts
(battery positive voltage).
Q: Is the measured voltage approximately 12 volts (battery
positive voltage)?
YES : Go to Step 4.
NO : Go to Step 3.