Headlamp: Description and Operation

Taillights and headlights illumination:

GENERAL DESCRIPTION CONCERNING HEADLIGHT AND TAILLIGHT







TAILLIGHT
The front ECU will light up the taillight when the tail light switch signal from the column switch is in the "ON" state and the built-in taillight replay is in the "ON" state.

NOTE: This item only considers the taillight lightup function and does not take into consideration the other functions. In actual driving, the taillights may be turned off due to the headlight automatic shut-down function. Refer to headlight automatic shut-down function, for the details.




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.

NOTE: The headlight automatic shutdown function can be disabled by the SWS configuration function.

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.







Headlights and high-beam indicator light
The front ECU lights up the headlight (LO) when the signal from the column switch to the headlight switch is in the "ON" state and the built-in head light relay (LO) is in the "ON" state. If the dimmer switch is turned on while the headlight relay (LO) is on, the front-ECU turns on the headlight relay (HI), causing the high-beam headlights to illuminate. What's more, ETACS-ECU lights up the high beam indicator light when the acknowledgment signal from the front ECU is in the "HI-BEAM ACK" state or the head light switch signal from the column switch is in the "PASS" state.

NOTE: This item only considers the headlight lightup function and doesn't take into consideration the other functions. In actual driving, the headlights may be turned off due to the headlight automatic shut-down function. Refer to headlight automatic shut-down function, for the details.








Headlight automatic-shutdown function
Even if the lighting switch (taillight switch or headlight switch) is ON, the head light (including the taillights) will automatically go off in the following conditions to prevent the battery from discharging as a result of forgetting to turn off lights. When the ignition key is turned from "ON" to "LOCK" (OFF) or "ACC" position with the lighting switch turned ON, and this state continues for three minutes, the light will automatically be turned off. If the driver's seat door is opened during these three minutes, the light will go off one second later.

NOTE: This function can be disabled by the adjustment procedures of SWS function (Refer to On Vehicle Service.)







Dimmer automatic reset function
The column switch (column ECU) resets the dimmer switch and prevents the high beam from lighting up when turning on the headlight again if the headlight switch is put in the "OFF" position while the high beam of the headlight is on (including the instance when the dimmer switch is erroneously put in the "ON" state upon passing operations) and resets the dimmer switch.







Daytime running light function
The daytime running light-ECU constantly lights up the high beam in a reduced beam state if the ignition switch is in the "ON" position when the headlight switch is in the "OFF" or "TAIL" position. If the headlights illuminate while the daytime running light function operates, the daytime running light-ECU shut the high-beam down.



Taillight control
The taillight lights up by turning on the taillight relay built-in the front ECU, after receiving the taillight switch ON signal from the column switch. What's more, the lights automatically dim with the headlight automatic shutdown function.
The tail lights are controlled by the Simplified Wiring System (SWS). For troubleshooting, refer to SWS Diagnosis.