Toyota 4Runner: System Description

Toyota 4Runner Service Manual / Vehicle Exterior / Lighting (ext) / Lighting System / System Description

SYSTEM DESCRIPTION

1. AUTOMATIC LIGHT CONTROL SYSTEM

(a) General

When the headlight dimmer switch is in the AUTO position, the automatic light control sensor detects ambient light levels and outputs a signal to the main body ECU (multiplex network body ECU). The main body ECU (multiplex network body ECU) controls the headlights, fog lights, clearance lights, taillights and license plate lights according to the signal from the automatic light control sensor.

(b) Fail-safe

If the main body ECU (multiplex network body ECU) detects a malfunction in the rain sensor, the main body ECU (multiplex network body ECU) performs fail-safe control to prohibit automatic light control. If the headlights or taillights are on, the lights remain on until the headlight dimmer switch is turned off.

2. LIGHT AUTO TURN-OFF SYSTEM

(a) The light auto turn-off system is used to prevent the driver from leaving the vehicle with the headlights, fog lights, clearance lights, taillights, or license plate lights on. The lights that turn off vary as shown in the table below according to the position of the headlight dimmer switch.

Switch Condition	Outline
Headlight dimmer switch in AUTO position	When the headlights, fog lights, clearance lights, taillights, or license plate lights are on, this system automatically turns them off when the delay time set through the customize function elapses after the ignition switch is turned off and a driver side door is opened and closed.
Headlight dimmer switch in head position	When the headlights, fog lights, clearance lights, taillights, or license plate lights are on, this system automatically turns off the headlights and front fog lights when the ignition switch is turned off. HINT: The clearance lights, taillights, and license plate lights remain on.
Headlight dimmer switch in tail position	When the clearance lights, taillights, or license plate lights are on, this system automatically turns off the front fog lights when the ignition switch is turned off. HINT: The clearance lights, taillights, and license plate lights remain on.

Switch Condition

Outline

Headlight dimmer switch in AUTO position

When the headlights, fog lights, clearance lights, taillights, or license plate lights are on, this system automatically turns them off when the delay time set through the customize function elapses after the ignition switch is turned off and a driver side door is opened and closed.

Headlight dimmer switch in head position

When the headlights, fog lights, clearance lights, taillights, or license plate lights are on, this system automatically turns off the headlights and front fog lights when the ignition switch is turned off.

HINT:

The clearance lights, taillights, and license plate lights remain on.

Headlight dimmer switch in tail position

When the clearance lights, taillights, or license plate lights are on, this system automatically turns off the front fog lights when the ignition switch is turned off.

HINT:

The clearance lights, taillights, and license plate lights remain on.

3. DAYTIME RUNNING LIGHT SYSTEM

(a) The daytime running light system is designed to automatically illuminate the dimmed high beam headlights, during the daytime to make the vehicle more visible to other vehicles.

The main body ECU (multiplex network body ECU) controls this system.

This system is enabled when the conditions below are met:
- Turn the ignition switch to ON.
- An engine speed signal is input (the engine is running).
- Parking brake switch off.
- Headlight dimmer switch is in the off (w/o DRL OFF switch), tail or AUTO position (and the low beam headlights are not turned on via the automatic light control system).

How To Proceed With Troubleshooting

CAUTION / NOTICE / HINT HINT: Use these procedures to troubleshoot the lighting system. *: Use the Techstream. PROCEDURE 1. VEHICLE BROUGHT TO WORKSHOP ...

Operation Check

OPERATION CHECK 1. AUTOMATIC LIGHT CONTROL SYSTEM OPERATION CHECK (a) Turn the ignition switch to ON. (b) Turn the headlight dimmer switch to the AUTO position. (c) Cover the automatic light contr ...

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