Toyota 4Runner: System Description

Toyota 4Runner Service Manual / Vehicle Exterior / Window / Glass / Window Defogger System / System Description

SYSTEM DESCRIPTION

1. WINDOW DEFOGGER SYSTEM DESCRIPTION

The thin heater wires of the defogger system are attached to the rear window and defog the rear window surface quickly. The system only operates when the back door power window is closed. The indicator light illuminates while the system is operating. The system automatically turns off when the back door power window is opened, or approximately 15 minutes after operation starts. For vehicles with an air conditioning system, there is a timer extension function which can operate the window defogger system for up to an additional 255 minutes.

HINT:

The timer extension function operates when the following conditions are met:

Ambient Temperature: 0°C (32°F) or less
Vehicle Speed: 31.1 mph (50 km/h) or more

2. FUNCTION OF MAIN COMPONENT

Component	Outline
Heater control assembly	Detects defogger switch operation and transmits signals to the air conditioning amplifier through the LIN communication line.
Engine room relay block, junction block (DEF relay)	Receives rear window defogger activation request signals from the air conditioning amplifier and supplies power to the rear window defogger.
Back door glass (Window defogger wire)	Receives power from the defogger relay and heats the defogger wire.
Multiplex network door ECU (Back door P/W)	Sends the back power window position signal to the main body ECU (multiplex network body ECU).
Main body ECU (Multiplex network body ECU)	Sends the back power window position signal to the air conditioning amplifier.
Back door power window regulator motor assembly	Sends the back power window position signal to the multiplex network door ECU (back door P/W).

3. SYSTEM FUNCTION

Function	Outline
Defog rear window surface	The defogger relay receives rear window defogger activation request signals from the air conditioning amplifier and defogs the rear window surface. Power received from the defogger relay heats the defogger wire.

Parts Location

PARTS LOCATION ILLUSTRATION ILLUSTRATION ...

System Diagram

SYSTEM DIAGRAM Communication Table Transmitter Receiver Signal Line Heater control assembly Air conditioning amplifier assemb ...

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