Headlamp: Description and Operation

HEADLIGHT AND TAILLIGHT




GENERAL DESCRIPTION CONCERNING HEADLIGHT AND TAILLIGHT
The following ECUs affect the functions and control of the headlights and the taillights.

TAILLIGHTS AND HEADLIGHTS ILLUMINATION

TAILLIGHT




If the column switch sends a taillight switch "ON" signal to the front-ECU, the front-ECU turns on its taillight relay, causing the taillights to illuminate.

NOTE: This description covers the taillights only. In actual driving, the taillights may be turned off due to the headlight automatic shut-down function. For the details of the headlight automatic shut-down function, refer to its Section.




HEADLIGHTS AND HIGH-BEAM INDICATOR LIGHT
If the column switch sends a headlight switch "ON" signal to the front-ECU, the front-ECU turns on its headlight relay (LO), causing the low-beam headlights to illuminate. 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.

If the acknowledgement signal, which the front-ECU sends to the SWS communication line, turns to "HI-BEAM ACK", or the headlight switch signal, which the column switch (column-ECU) sends to the SWS communication line, turns to "PASSING", the ETACS-ECU will illuminate the high-beam indicator light.

NOTE: This description covers the headlights only. In actual driving, the headlights may be turned off due to the headlight automatic shut-down function. For the details of the headlight automatic shut-down function, refer to its Section.




HEADLIGHT AUTOMATIC-SHUTDOWN FUNCTION
Even if the lighting switch (tail light switch or headlight switch) is ON, the head light (including the tail lights) 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 configuration function (Refer to On-vehicle Service Simplified Wiring System (SWS)).




DIMMER AUTOMATIC RESET FUNCTION
If the headlight switch is turned off while the high-beam headlights are on, the dimmer switch will be reset. Because of this, the headlights will illuminate at low beam when they are turned on at next opportunity. The dimmer switch will be also reset if the dimmer switch is turned on unintentionally while the passing switch is operated.




Daytime running light function
The daytime running light-ECU constantly lights up the low-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 lights up the low-beam in a normal beam state.