Diesel Data: Automotive Repair

Headlight and Taillight




GENERAL DESCRIPTION CONCERNING THE HEADLIGHTS AND TAILLIGHTS

The following ECUs affect the functions and control of the headlights and the taillights.






Taillights and headlights illumination

TAILLIGHTS





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-off function. For the details of the headlight automatic shut-off function, refer to .

Headlights





If the column switch sends a headlight switch "ON" signal to the front-ECU, the front-ECU turns on its headlight relay (LOW), causing the low-beam headlights to illuminate. If the dimmer switch is turned on while the headlight relay (LOW) is on, the front-ECU turns on the headlight relay (HIGH), causing the high-beam headlights to illuminate.
NOTE:
This description covers the headlights only. In actual driving, the headlights may be turned off due to the headlight automatic shut-off function. For the details of the headlight automatic shut-off function, refer to .

High-beam indicator light

At the same time that the high-beams are illuminated, the ETACS-ECU sends a signal to illuminate the high beam indicator via the CAN bus line. The combination meter receives the transmitted signal and turns the high-beam indicator on and off.

Headlight automatic-shutdown function





Even if the lighting switch (taillights switch or headlight switch) is ON, the headlights
(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.
If 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:
The headlight automatic-shutoff function can be customized on vehicles equipped with a multi center display (middle grade type). Refer to Adjustments.

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 the next time that they are turned on. 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 ETACS-ECU outputs the daytime running light forced-OFF signal to the front-ECU based on the input signal sent via CAN communication. The front-ECU controls illumination and extinction of the daytime running light according to the daytime running light forced-OFF signal.
Illumination control of daytime running lights

- If the engine is started when the parking brake is not pulled, the headlights illuminate with the brightness reduced.
- If the engine is started while the parking brake is pulled, the daytime running light function OFF mode is entered and the headlights do not illuminate. If the parking brake is released, the OFF mode is cancelled and the headlights illuminate.


General circuit diagram for the taillights





General circuit diagram for the headlights