Window Defogger System: Inspection

INSPECT CENTER CLUSTER MODULE SWITCH
1. Check operation of the defogger timer.
  1. Connect the battery's positive (+) lead to terminal 3 and the negative (-) lead to terminal 4.
  2. Connect the battery's positive (+) lead to terminal 4 through a 1.4 W test bulb.
  3. Push the rear window defogger switch ON, check that the switch and the test bulb illuminate for 12 to 18 minutes, and then they go off.
  If the result is not as specified, replace the module switch.
  
  Fig 1: Inspecting Center Cluster Module Switch
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT BACK DOOR GLASS (DEFOGGER WIRE)

NOTE:

When cleaning the glass, wipe the glass along the wire using a soft, dry cloth. Take care not to damage the wires.
Do not use detergents or glass cleaners that have abrasive ingredients.
When measuring voltage, wrap a piece of tinfoil around the tip of the negative tester probe and press the foil against the wire with your finger, as shown in Fig 2.

Fig 2: Wrapping Piece of Tinfoil Around Tip Of Negative Probe And Pressing Foil Against Wire With Finger

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Turn the ignition switch ON.
Turn the defogger switch ON.

Measure the voltage at the center of each defogger wire, as shown in Fig 3.

Standard:

STANDARD VOLTAGE CONDITIONS

Voltage	Criteria
Approx. 5 V	Wire is not broken
Approx. 10 or 0 V	Wire is broken

Fig 3: Measuring Voltage At Center Of Each Defogger Wire

HINT:

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 and the wire end on the ground side.

Place the voltmeter positive (+) lead against the defogger wire on the battery side.
Place the voltmeter negative (-) lead with the foil strip against the wire on the ground side.
Slide the positive (+) lead from the battery side to the ground side.
The point where the voltage drops from approximately 10 V to 0 V is where the defogger wire is broken.
HINT:

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

Fig 4: Defective Defogger Wire Test Diagram
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
If necessary, repair the 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.
  
  Fig 5: Placing Masking Tape Along Both Side Of Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Thoroughly mix the repair agent (Dupont paste No. 4817).
4. Using a fine tip brush, apply a small amount of the agent to the wire.
  
  Fig 6: Applying Small Amount Of Repair Agent To Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. After a few minutes, remove the masking tape.
  NOTE: Do not repair the defogger wire again for at least 24 hours.

INSPECT DEFOGGER RELAY
1. Measure the resistance.
  Standard:
  
  Fig 7: Defogger Relay Standard Conditions Table
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  If the result is not as specified, replace the relay.
  
  Fig 8: Identifying Defogger Relay Circuit And Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002