Defogger System: Inspection

WARNING: This page is about a different car, the 2002 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

Inspect defogger timer operation .
1. Connect the positive (+) lead from the battery to terminals 1, 7 and negative (-) lead to terminal 9.
2. Connect the positive (+) lead from the battery to terminal 4 through a 1.4 W test bulb.
3. Push the defogger switch ON, and check that the test bulb and indicator light up for 12 to 18 minutes, then the indicator light go out.
If operation is not as specified, replace the inner printed circuit board.
Inspect rear defogger relay continuity .

Fig 2: Inspecting Rear Defogger Relay Continuity
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 3: Displaying Defogger Relay Continuity Specifications
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

If continuity is not as specified, replace the relay.
W/ mirror heater: Inspect mirror heater operation .
1. Connect the positive (+) lead from the battery to terminal 2 and the negative (-) lead to terminal 6.
2. Check that the mirror becomes warm.
NOTE: It will take a short time for the mirror to become warm. If the mirror does not become warm, replace the mirror assembly.
Inspect defogger wire .
NOTE:
- When cleaning the glass, use a soft, dry cloth, and wipe the glass in the direction of the wire. Take care not to damage the wires.
- Do not use detergents or glass cleaners with abrasive ingredients.
- When measuring voltage, wind a piece of tin foil around the top of the negative probe and press the foil against the wire with your finger, as shown.
1. Turn the ignition switch ON.
2. Push the defogger switch ON.
3. Inspect the voltage at the center of each heat wire, as shown.
  
  Fig 6: Inspecting Voltage At Each Heat Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 7: Displaying Voltage Criteria
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  NOTE: If there is approximately 10 V, the wire is broken between the center of the wire and the positive (+) end. If there is no voltage, the wire is broken between the center of the wire and ground.
4. Place the voltmeter positive (+) lead against the defogger positive (+) terminal.
5. Place the voltmeter negative (-) lead with the foil strip against the heat wire at the positive (+) terminal end and slide it toward the negative (-) terminal end.
6. The point where the voltmeter deflects from zero to several V is the place where the heat wire is broken.
  NOTE: If the heat wire is not broken, the voltmeter indicates 0 V at the positive (+) end of the heat wire but gradually increases to about 12 V as the meter probe is moved to the other end.
  
  Fig 8: Measuring Voltage On A Broken Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
If necessary, repair defogger wire .
1. Clean the broken wire tips with grease, wax and silicone remover.
2. Place the masking tape along both sides of the wire to be repaired.
  
  Fig 9: Masking Off Broken Wire For Repair
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Thoroughly mix the repair agent (Dupont paste No. 4817 or equivalent).
4. Using a fine top brush, apply a small amount to the wire.
5. After a few minutes, remove the masking tape.
6. Do not use the defogger wire for at least 24 hours.