Toyota 4Runner manuals

Toyota 4Runner: Window Defogger Wire

On-vehicle Inspection





  • When cleaning the glass, wipe the glass along the wire using a soft, dry cloth. Take care not to damage the defogger wires.
  • Do not use detergents or glass cleaners that have abrasive ingredients.
  • When measuring voltage, wrap a piece of tin foil around the tip of the negative (-) tester probe and press the foil against the wire with your finger as shown in the illustration.
Text in Illustration


Defogger Wire


Tin Foil


Tester Probe

(a) Turn the ignition switch to ON.

(b) Turn the defogger switch on.

(c) Measure the voltage at the center of each defogger wire as shown in the illustration.

Standard Voltage:



Approx. 5 V

Wire is not broken

Approx. 10 or 0 V

Wire is broken

Text in Illustration




If there is approximately 10 V, the wire may be faulty between the center of the wire and the wire end on the battery side. If there is no voltage, the wire may be faulty between the center of the wire end and the wire end on the ground side.

(d) Place the voltmeter positive (+) lead against the defogger wire on the battery side.

(e) Place the voltmeter negative (-) lead with the foil strip against the wire on the ground side.

(f) Slide the positive (+) lead from the battery side to the ground side.

(g) The point where the voltage drops from approximately 10 V to 0 V is where the defogger wire is broken.


If the defogger wire is not broken, the voltmeter indicates 0 V at the positive (+) end of the defogger wire and gradually increases to approximately 12 V as the meter probe moves to the other end.

Text in Illustration


Ground Side


Foil Strip


Approximately 10 V


0 V


Broken Wire


Battery Side





(a) Clean the broken wire tips with grease, wax and silicone remover.

(b) Place masking tape along both sides of the wire.

(c) Thoroughly mix the repair agent.

DuPont paste:

No. 4817 or equivalent

Text in Illustration


Repair Point


Masking Tape


Broken Wire

(d) Using a fine tip brush, apply a small amount of the agent to the wire.

Text in Illustration


Fine Tip Brush


Repair Point

(e) After a few minutes, remove the masking tape.


Do not allow electricity to flow in the defogger wire for at least 24 hours.

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