Information Bus: Description and Operation
GENERAL DESCRIPTIONCOMMUNICATION METHOD
As shown signal wires used exclusively for transmitting multiplex signal data connect the ETACS-ECU, front-ECU, column switch (incorporating the column-ECU) and these components communicate with each other.
OPERATION
TONE ALARM FUNCTION
Ignition key reminder tone alarm function
When the driver's door is opened (driver's door switch ON) without removing the ignition key [ignition switch to "LOCK" (OFF) or "ACC" position], the tone alarm will sound intermittently to remind the driver that the ignition key has not been removed.
Light reminder tone alarm function
When the driver's door is opened (driver's door switch ON) with lighting switch (taillight switch or headlight switch) in the ON position and ignition switch in the "LOCK" (OFF) or "ACC" position, the tone alarm will sound continuously to remind the driver that the lights (taillights or headlights) are ON. This function does not work if the taillights or headlights are switched off through the headlight automatic shutdown function. In addition, the ignition key reminder tone alarm function has a priority over this function.
Seat belt tone alarm function
When the ignition switch is turned to the "ON" position without fastening the seat belts (seat belt switch OFF), the tone alarm will sound for approximately six seconds to warn the driver to fasten the seat belts. When the seat belts are fastened, the tone alarm will stop sounding.
CENTRAL DOOR LOCKING SYSTEM
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, all the 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.
Forgotten key prevention function
- If the driver's door is open (door switch turned ON), when the key is inserted in the ignition switch (key reminder switch turned OFF), the ETACS-ECU activates the door unlock relay for 0.25 seconds to prevent the door from being locked.
- If you try to lock either the driver's or passenger's door when the passenger's door is open (door switch turned ON) and the key is inserted in the ignition switch (key reminder switch turned OFF), the ETACS-ECU prevents the doors from being locked by activating the door unlock relay for 0.25 seconds.
POWER WINDOW RELAY CONTROL
Power window relay operation
If the ignition switch is turned to "ON" position, the power window relay is energized to activate the power windows.
Power window timer function
When the ignition switch is turned from the "ON" position to "LOCK" (OFF) or "ACC" position, the power windows can be operated for 30 seconds. If driver's or front passenger's door is opened for the 30 seconds, the power windows will be immobilized at that point.
KEYLESS ENTRY SYSTEM
Keyless entry answerback function
If the RKE transmitter "LOCK" or "UNLOCK" switch is pressed while the ignition key is removed, the doors can be locked or unlocked. If the doors are closed, the hazard warning lights, the dome light and the horn will operate due to answerback function. Because of the answerback function, the hazard warning lights flash twice, and the horn sounds once, the dome light flashes twice when the doors are locked. Meanwhile, when the doors are unlocked, the hazard warning lights flash once and the dome light illuminates for 30 seconds. The hazard and the horn answerback functions can be cancelled by using the RKE transmitter.
Trunk lid opener function
After "TRUNK" switch of the transmitter is turned "ON" twice within five seconds without ignition key in the key hole, ETACS-ECU makes trunk lid opener actuator open the trunk lid.
WINDSHIELD WIPERS AND WASHERS
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 seconds 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.
SEAT BELT WARNING LIGHT
If the driver turns the ignition switch to the "ON" position without wearing the seat belt, the seat belt warning light illuminates to alert the driver to wear the seat belt.
HEADLIGHT
Headlight automatic shutdown function
When the headlights or taillights are on, and the ignition switch is turned from "ON" to "LOCK" (OFF) or "ACC" position or the ignition key is removed, the headlights will be switched off in three minutes. If the driver's door is opened within that three-minute period, the headlights will be switched off automatically. This prevents the battery from discharging.
Headlight dimmer switch automatic resetting function
This function allows the dimmer switch to be reset to the low-beam position whenever the headlight switch is turned to the ON position.
FLASHER TIMER
Turn-signal light
When the ignition switch is turned to the "ON" position and turn-signal light switch is placed in the ON position for right or left turn-signaling, the system generates turn-signal light drive signals (flashing signals). The system also notifies of a blown turn-signal light bulb by shortening the flashing intervals of the corresponding indicator light.
Hazard warning light
The system detects a change from OFF to ON of the hazard warning input signal and activates or shuts off the hazard warning lights accordingly.
FOG LIGHT
The fog light switch becomes active only when the headlights are at the low-beam mode. Therefore, if the headlights are turned off, the fog lights will also be switched off. When the headlights are turned on during the next key cycle, the fog lights will be off regardless of the fog light switch position.
DOME LIGHT
With the dome light switch in the "door controlled operation" (middle) position, the ETACS-ECU controls the dome light operation as follows:
- When a door is opened from outside or inside [with the ignition switch turned to "LOCK" (OFF)]: When a door is opened, the ETACS-ECU causes the dome light to be illuminated at 100 percent intensity. When the door is closed, it dims the dome light to 65 percent intensity and approximately 30 seconds later, turns out the light completely. During this period (timer controlled period), the dome light goes out if the ignition switch is turned "ON" or the doors are locked.
- When a door is opened or closed with the ignition switch in the "ON" position: The dome light illuminates at 100 percent intensity when a door is opened and turned out when it is closed.
- When no door is opened and the ignition key is removed: The dome light is illuminated at 100 percent intensity and turned off approximately 30 seconds later. During that time (timer-controlled period), the dome light goes out if the ignition key is inserted and turned to "ON" or the door locking system is activated.
- Dome light's answerback operation in response to door lock control by keyless entry system: To allow the driver to confirm the doors have locked by the keyless entry system, the ETACS-ECU causes the dome light to blink twice when the doors are locked by the RKE system and to illuminate for approximately 15 seconds when the doors are locked. The dome light's answerback operation in response to a keyless entry system control action is accompanied by flashing of the hazard warning lights.
INTERIOR LIGHT AUTOMATIC SHUTDOWN FUNCTION
This function prevents the battery from being discharged when the door is open or the dome light remains on with the ignition switch at the "LOCK" (OFF) position. The ETACS-ECU turns on its "keep" relay to switch off the battery power supply to the interior lights when the interior light loaded signal and all door switches remain on for approximately 30 minutes with the ignition switch at positions other than ACC. Then the interior lights will be switched off. If the ignition switch is turned on again, the ETACS-ECU turns on its "keep" relay to illuminate the interior lights.
DOOR-AJAR INDICATOR LIGHT
This indicator light warns the driver that door(s) are not closed. If a door switch is on, the ETACS-ECU operates the door-ajar indicator light on the combination meter.
THEFT-ALARM SYSTEM
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.
Panic alarm function
With the theft-alarm function armed, pressing the panic button on the keyless entry system transmitter causes the horn (theft-alarm horn and horn) to sound for about three minutes in an attempt to prevent theft. The alarm is turned off by pressing any switch on the transmitter.
CONFIGURATION FUNCTION
The keyless entry hazard answerback function can be adjusted by the special operation. Then they can be returned to the initial condition.
BEFORE TROUBLESHOOTING
Before carrying out troubleshooting, check the following two items.
- Make sure that the ETACS-ECU, the junction block (J/B), the front-ECU and the engine compartment relay box are connected securely.
- Make sure that fuses and fusible links related to relevant systems are not blown.