DESCRIPTION
| WARNING | Deactivate air bag system before performing any service operation. See AIR BAG RESTRAINT SYSTEMS article in RESTRAINTS. DO NOT apply electrical power to any component on steering column without first deactivating air bag system. Air bag may deploy. |
Note. Multiplex control system may be referred to as Simplified Wiring System (SWS).
Multiplex control system uses Electronic Time Alarm Control System (ETACS) ECU, front-ECU and column-ECU to process signal data to control on/off operation of electrical loads in order to transmit and receive multiplex data. (Scheme 1)
Scheme 1
Central Door Locking System Operation
- When the driver's inside lock knob is locked, the lock relay inside the ETACS-ECU turns on to lock all doors. However, even if the driver's inside lock knob is unlocked, the all doors are not unlocked.
- With all the doors locked, turning the key in the driver's door lock key cylinder unlocks the door. Turning it again makes the door unlock relay close to send a signal for unlocking all doors. When the key in the front passenger's door lock key cylinder is operated, the lock or unlock relay inside the ETACS-ECU is turned on to lock or unlock all doors.
- When the door lock switch (built into the power window switch) is operated, the lock or unlock relay inside the ETACS-ECU is turned on to lock or unlock all doors.
Power Window Relay Operation
If the ignition switch is turned to ON position, the power window relay is energized to activate the power windows.
Windshield Low-Speed (And High-Speed) Wiper Operation
- If the windshield low-speed wiper switch is turned to the ON position with the ignition switch at the ACC or ON position, the column switch sends a low-speed wiper ON and high-speed wiper OFF signals to the front-ECU. This turns the wiper signal on and the wiper speed switching relay off (low-speed), causing the wipers to operate at low-speed.
- If the windshield high-speed wiper switch is turned to the ON position, the column switch sends a low-speed wiper OFF and high-speed wiper ON signals to the front-ECU. This turns both the wiper signal and the wiper speed switching relay on (high-speed), causing the wipers to operate at high-speed.
Windshield Intermittent Wiper Operation
The ETACS-ECU calculates the wiper operation interval according to the voltage signal sent from the column switch. Then the ETACS-ECU sends a signal to the front-ECU. The front-ECU determines the wiper operation interval and turns on the wiper relay signal relay. This causes the wiper auto stop relay to turn on. Then the wiper auto stop relay will turn off after the wipers reach the park position. This causes the wiper signal relay and then the wipers to turn off. If the wiper signal relay remains off for the wiper operation interval, the relay turns on again, causing the wipers to operate in intermittent mode.
Windshield Mist Wiper Operation
- If the windshield mist wiper switch is turned to the ON position with the ignition switch at the ACC or ON position, the mist wiper high-speed operation signal is sent to the front-ECU. This signal turns on the wiper speed switching relay, causing the wipers to work at high-speed while the mist switch is on.
- While the windshield mist wiper switch remains turned on when the intermittent mode is still working, the wipers work as the mist wiper. However, the wipers return to the intermittent mode again when the switch is changed back to INT position.
- To prevent the windshield mist wiper from operating when the windshield wiper switch is turned OFF, the windshield mist wiper does not work for 0.5 second after the windshield intermittent wiper switch, the windshield low-speed wiper switch and the windshield high-speed wiper switch are turned OFF.
Windshield Washer Operation
- If the windshield washer switch is turned to ON position with the ignition switch at ACC or ON position, the windshield washer ON signal is sent to the front-ECU, causing the windshield wiper signal to turn on after 0.3 seconds. After the windshield washer switch signal turns off, the windshield wiper signal turns off in three seconds.
- If the windshield washer switch is turned on while the windshield wiper is at intermittent mode, when the windshield washer switch is turned OFF within 0.2 seconds, the wiper works only once to perform mist operation by the windshield washer switch. When the ON condition of the windshield washer switch continues more than 0.2 seconds, the wiper performs the same movement as normal condition from the time when 0.2 seconds has elapsed and then returns to the intermittent motion.
Theft-alarm System Operation
If a door, trunk lid or hood is opened, when the theft-alarm system has been armed the horn (theft-alarm horn and horn) will sound and headlights flash (high-beam) intermittently for a period of three minutes.
INSPECTION PROCEDURE C-3: ALL DOORS DO NOT LOCK OR UNLOCK WITH JUST DOOR LOCK SWITCH OPERATION
Note. To perform this test, MUT-II Scan Tool (MB991502) and Test Harness Set (MB991223) must be used.
| CAUTION | To prevent damage to Scan Tool (MB991502), always turn the ignition switch to the LOCK (OFF) position before connecting or disconnecting scan tool. |
Using the pulse check, check the input signal. See PULSE CHECK . Check the input signals from the door lock switch: Connect scan tool to the Data Link Connector (DLC). When the driver's or the front passenger's door lock switch is moved from LOCK to UNLOCK or vice versa, check if scan tool sounds or not. Does scan tool sound when the driver's or the front passenger's door lock switch is moved from LOCK to UNLOCK or vice versa? If YES, replace the ETACS-ECU. All the doors should be locked and unlocked by the door lock switch. If NO, refer to INSPECTION PROCEDURE O-7: THE ETACS-ECU DOES NOT RECEIVE ANY SIGNAL FROM THE DOOR LOCK SWITCH (INCORPORATED IN POWER WINDOW MAIN SWITCH AND POWER WINDOW SUB SWITCH) .
INSPECTION PROCEDURE C-4: ALL DOORS DO NOT LOCK OR UNLOCK WITH JUST DOOR LOCK KEY CYLINDER OPERATION
Note. To perform this test, MUT-II Scan Tool (MB991502) and Test Harness Set (MB991223) must be used.
| CAUTION | To prevent damage to Scan Tool (MB991502), always turn the ignition switch to the LOCK (OFF) position before connecting or disconnecting scan tool. |
Using pulse check, check the input signal. See PULSE CHECK . Check the input signals from the door lock key cylinder switch. Connect scan tool to the Data Link Connector (DLC). When the doors are locked and unlocked by using the driver's or front passenger's door lock key cylinder, check that scan tool sounds. When the doors are locked and unlocked by using the driver's or front passenger's door lock key cylinder, does scan tool sound? If YES, replace the ETACS-ECU. All the doors should be locked and unlocked by using each door lock key cylinder switch. If NO, refer to INSPECTION PROCEDURE O-5: THE ETACS-ECU DOES NOT RECEIVE ANY SIGNAL FROM DRIVER'S OR FRONT PASSENGER'S DOOR LOCK KEY CYLINDER SWITCH .
INSPECTION PROCEDURE C-5: ALL DOORS DO NOT LOCK WITH JUST DRIVER'S INSIDE LOCK KNOB LOCK OPERATION
Note. To perform this test, MUT-II Scan Tool (MB991502) and Test Harness Set (MB991223) must be used.
| CAUTION | To prevent damage to Scan Tool (MB991502), always turn the ignition switch to the LOCK (OFF) position before connecting or disconnecting scan tool. |
Using the pulse check, check the input signal. See PULSE CHECK . Check the input signals from the driver's or front passenger's door lock actuator switch. Connect scan tool to the Data Link Connector (DLC). When the driver's inside lock knob is locked or unlocked, check if scan tool sounds or not. Does scan tool sound when the driver's or the front passengers inside lock-knob Is moved from LOCK to UNLOCK or vice versa? If YES, replace the ETACS-ECU. Check that all the doors can be locked or unlocked by operating the driver's inside lock knob. If NO, refer to INSPECTION PROCEDURE O-6: THE ETACS-ECU DOES NOT RECEIVE ANY SIGNAL FROM THE DRIVER'S, FRONT PASSENGER'S OR REAR DOOR LOCK ACTUATOR SWITCH .