Section 944 (Defogger System): Inspection

WARNING: This page is about a different car, the 2004 Scion xB. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT CENTER CLUSTER MODULE SWITCH
1. Check operation of the defogger timer.
  1. Connect the positive (+) lead from the battery to terminal 3 and the negative (-) lead to terminal 4.
  2. Connect the positive (+) lead from the battery 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 illuminates 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 and dry cloth. Take care not to damage the wires.
Do not use detergents or glass cleaners including 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.

Fig 2: Inspecting Back Door Glass
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Check the voltage at the center of each defogger wire, as shown in the illustration.

Standard:

DEFOGGER WIRE STANDARD

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

Fig 3: Turning On Defogger Switch

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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.

Fig 4: Placing Voltmeter (+) Lead Against Defogger Wire On Battery Side
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Slide the positive (+) lead from the battery side to the ground side.
The point where the voltage jumps 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.
If necessary, repair the defogger wire.
1. Clean the broken wire tips with grease, wax and silicons remover.
2. Place the masking tape along both sides of the wire.
3. Thoroughly mix the repair agent (Dupont paste No. 4817).
  
  Fig 5: Identifying Repair Point
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Using a fine tip brush, apply a small amount of the agent to the wire.
5. After a few minutes, remove the masking tape.
  NOTE: Do not repair the defogger wire again for at least 24 hours.
  
  Fig 6: Applying Small Amount Of Agent To Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT DEFOGGER RELAY

Check the resistance.

Standard:

DEFOGGER RELAY STANDARD

Terminal No.	Specified Condition
3 - 5	10 kΩ or higher
3 - 5	Below 1Ω (When battery voltage is applied to terminals 1 and 2)

If the result is not as specified, replace the relay.

Fig 7: Checking Resistance