Page 81 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-81
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: Probe Harness
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-82
STEP 1. Use diagnostic tool MB991958 to select "ECU
COMM Check" on the SWS monitor display.
Check the ETACS-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 "Interactive Diagnosis."
b. Select "System select."
c. Select "SWS."
d. Select "SWS MONITOR."
e. Select "ECU COMM Check."
(4) DIAGNOSTIC TOOL MB991958 should show "OK" on the
"ECU COMM Check" menu for the "ETACS ECU" menu.
Q: Is "OK" displayed for the "ETACS ECU" menu?
YES : Go to Step 2.
NO : Refer to Inspection Procedure A-3 "Communication
with the ETACS-ECU is not possible P.54B-74."
Page 83 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-83
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 system should communicate with the
front-ECU normally.
STEP 3. Check the battery power supply circuit to the
front-ECU. Measure the voltage at front-ECU connector
A-11X.
(1) Disconnect front-ECU connector A-11X and measure the
voltage available at the relay box side of the connector.
(2) Measure the voltage between terminal 5 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 5.
NO : Go to Step 4.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-84
STEP 4. Check the wiring harness between front-ECU
connector A-11X (terminal 5) and the battery.
Q: Is the wiring harness between front-ECU connector
A-11X (terminal 5) 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. The system
should communicate with the front-ECU normally.
STEP 5. Check front-ECU connector A-12X for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is front-ECU connector A-12X in good condition?
YES : Go to Step 6.
NO : Repair or replace the damaged component(s). Refer
to GROUP 00E, Harness Connector Inspection
P.00E-2. The system should communicate with the
front-ECU normally.
STEP 6. Check the ground circuit to the front-ECU.
Measure the resistance at front-ECU connector A-12X.
(1) Disconnect front-ECU connector A-12X and measure the
resistance available at the relay box side of the connector.
(2) Measure the resistance value between terminal 21 and
ground.
The resistance should be 2 ohms or less.
Q: Is the measured resistance 2 ohms or less?
YES : Go to Step 8.
NO : Go to Step 7.
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-85
STEP 7. Check the wiring harness between front-ECU
connector A-12X (terminal 21) and ground.
Q: Is the wiring harness between front-ECU connector
A-12X (terminal 21) and ground 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 system
should communicate with the front-ECU normally.
STEP 8. Check ETACS-ECU connector C-218 for loose,
corroded or damaged terminals, or terminals pushed back
in the connector.
Q: Is ETACS-ECU connector C-218 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. The system should communicate with the
front-ECU normally.
STEP 9. Check the wiring harness between front-ECU
connector A-12X (terminal 30) and ETACS-ECU connector
C-218 (terminal 53).
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SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-86
NOTE: Also check intermediate connector C-29 for loose, cor-
roded, or damaged terminals, or terminals pushed back in the
connector. If intermediate connector C-29 is damaged, repair or
replace the connector as described in GROUP 00E, Harness
Connector Inspection P.00E-2.
Q: Is the wiring harness between front-ECU connector
A-12X (terminal 30) and ETACS-ECU connector C-218
(terminal 53) in good condition?
YES : Go to Step 10.
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 system
should communicate with the front-ECU normally.
STEP 10. Replace the front-ECU.
(1) Replace the front-ECU.
(2) The system should communicate with the front-ECU
normally.
Q: Can the system communicate with the front-ECU?
YES : No action is necessary and testing is complete.
NO : Replace the ETACS-ECU. The system should
communicate with the front-ECU normally.
Page 87 of 1500
SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-87
INSPECTION PROCEDURE A-5: Communication with the Sunroof-ECU is not Possible.
.
CIRCUIT OPERATION
Power to the sunroof motor assembly is supplied
through fusible link (5).
When the ignition switch (IG2) signal is on, the
sunroof motor assembly is ready to operate.
Refer to circuit diagrams GROUP-90
Refer to configuration diagrams GROUP-80
.
TECHNICAL DESCRIPTION (COMMENT)
The power supply circuit or the communication circuit
to the sunroof motor assembly or the sunroof motor
assembly may be defective.
.
TROUBLESHOOTING HINTS
The wiring harness or connectors may have
loose, corroded, or damaged terminals, or termi-
nals pushed back in the connector
The sunroof motor assembly may be defective
The ETACS-ECU may be defective
Page 88 of 1500

SYMPTOM PROCEDURES
SIMPLIFIED WIRING SYSTEM (SWS)54B-88
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
STEP 1. Check sunroof motor assembly connector D-04
for loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Is sunroof motor assembly connector D-04 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. The system should communicate with the
sunroof-ECU normally.
STEP 2. Check the fusible link (5) line of power supply
circuit to the sunroof motor assembly. Measure the voltage
at sunroof motor assembly connector D-04.
(1) Disconnect sunroof motor assembly connector D-04 and
measure the voltage available at the wiring harness side of
the connector.
(2) Measure the voltage between terminal 1 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.