Toyota Tundra Service Manual: System Description

SYSTEM DESCRIPTION

AUTOMATIC LIGHT CONTROL SYSTEM

(a) When the light control switch is in the Auto position, the automatic light control system detects ambient light levels and controls the headlights, taillights, front fog lights (w/ Front Fog Light) parking lights, front side marker lights and license plate lights.

LIGHT AUTO TURN-OFF SYSTEM

(a) The light auto turn-off system is used to prevent the exterior lights from being accidentally left on (headlights, taillights, front fog lights (w/ Front Fog Light), parking lights, license plate lights and front side marker lights).

(1) This system has the following function.

DAYTIME RUNNING LIGHT SYSTEM

(a) The daytime running light system is designed to automatically illuminate the headlights (high intensity parking lights), during the daytime to make the car 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:
  • The ignition switch is ON.
  • An engine speed signal is input (the engine is running).
  • Parking brake is released.
  • Headlight dimmer switch not in the DRL off position. (w/ DRL Off Switch)
  • Light control 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).

AUTOMATIC HIGH BEAM SYSTEM (w/ Automatic High Beam System)

(a) General

The automatic high beam system enhances the illumination of the area in front of the vehicle to improve visibility for the driver. It works by detecting light from the front of the vehicle, using the forward recognition camera, and turns the high beams of the headlights on or off automatically.

(b) Function of Main Components

(c) Basic Function

(1) When all of the following conditions are met, the automatic high beam system is activated and the automatic high beam indicator light turns on:

• Turn the ignition switch to ON.
• The light control switch is in the Auto or Head position and the low beam headlights are on.
• The headlight dimmer switch is in the high position.
• The auto high beam switch is on.

(2) When all of the following conditions are met, the high beams automatically turn on after a short delay:

• Vehicle speed is more than approximately 34 km/h (21 mph).
• The area in front of the vehicle is dark.
• There are no oncoming vehicles with headlights on.
• There are no preceding vehicles with taillights on.
• There are few streetlights along the street ahead.

(3) When any of the following conditions are met, the high beams automatically turn off after a short delay:

• Vehicle speed is less than approximately 27 km/h (17 mph).
• There are oncoming vehicles with headlights on.
• There are preceding vehicles with taillights on.
• Light from streetlights ahead is higher than a specified threshold.

(4) When any of the following conditions are met, the automatic high beam system will be canceled and the indicator light will turn off:

• Turn the ignition switch off.
• The light control switch is turned to any position except the Auto or Head position.
• The headlight dimmer switch is moved to the low position.
• The auto high beam switch is off.

HINT:

It is possible to manually turn the high beams on and off by performing either of the following operations:

• When changing the high beams controlled by the automatic high beam system to the low beams manually, move the headlight dimmer switch to the low position. The automatic high beam system will be canceled and the low beams will be turned on. To enable the automatic high beam system again, move the headlight dimmer switch to the high position.
• When changing the low beams controlled by the automatic high beam system to the high beams manually, turn the auto high beam switch off. The automatic high beam system will be canceled and the high beams will be turned on. To enable the automatic high beam system again, turn the auto high beam switch on.

HINT:

The automatic high beam system monitors the area in front of the vehicle using the forward recognition camera and makes a judgment to turn on the high beams when the surrounding area is dark (there are no headlights from oncoming vehicles and no taillights from preceding vehicles). High beam control limitations:

• When the surrounding area is not dark enough, the high beams will not turn on even if the low beam headlights are turned on by the automatic light control system and the automatic high beam indicator light on the combination meter assembly illuminates. (The light level sufficient to turn the auto low beams on is not the same as the light level required to automatically change the low beams to high beams.)
• When an oncoming vehicle suddenly appears at a sharp curve or a vehicle crosses the path of the vehicle, the high beams may remain on.
• When the fog lights of an oncoming vehicle are detected, the high beams may be turned off.
• The timing of the high beams turning on and off may differ depending on the brightness of headlights or fog lights from oncoming vehicles or the taillights of preceding vehicles.
• The timing of the high beams turning on and off may differ between normal conditions (good weather) and when driving on wet, frozen or snowy roads.
• The timing of the high beams turning on and off may differ depending on the number of occupants and amount of cargo present.
• Be aware that on some occasions, the high beams may switch on and off unexpectedly.

HINT:

Forward recognition camera continually monitors the light level in the area in front of the vehicle. There is a delay in turning on the high beams. Even when there is no ambient light, the high beams will not turn on immediately. The delay will vary depending on the situation.

MANUAL HEADLIGHT BEAM LEVEL CONTROL SYSTEM

(a) The manual headlight beam level control system controls each headlight leveling motor based on the headlight leveling switch operation in order to change the headlight reflector angle.

ILLUMINATION CONTROL SYSTEM (Illuminated Entry System)

HINT:

Perform this inspection with the interior dome light switch assembly, roof console box assembly (front interior light) and No. 1 room light assembly (rear interior light) are DOOR position.

(a) The illuminated entry system has the following control functions:

BATTERY SAVING CONTROL SYSTEM

(a) The battery saving control system has the following control functions: