Section 492 (Defogger System): Inspection

WARNING: This page is about a different car, the 2004 Toyota RAV4. However, it is still accessible from the selected car via links, so may be relevant.

CHECK DEFOGGER SWITCH CIRCUIT

Disconnect the connector from the heater control assembly, and check the connector on the wire harness side.

Fig 1: Identifying Heater Control System

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DEFOGGER SWITCH CIRCUIT SPECIFIED CONDITIONS

Tester Connection	Condition	Specified Condition
1 - Body ground	Ignition switch OFF --> ON	Below 1 V --> 10 - 14 V
4 - Body ground	Light control switch OFF --> TAIL	Below 1 V --> 10 - 14 V
6 - Body ground	Constant	Continuity
7 - Body ground	Ignition switch OFF --> ON	Below 1 V --> 10 - 14 V
9 - Body ground	Constant	Continuity

If the circuit is as specified, replace the heater control assembly.

INSPECT REAR DEFOGGER RELAY CONTINUITY

Fig 2: Identifying Rear Defogger Relay Circuit

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

REAR DEFOGGER RELAY CONTINUITY

Tester Connection	Specified Condition
3 - 5	No continuity
3 - 5	Continuity (When battery voltage is applied to terminals 1 and 2)

If the 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 if the mirror becomes warm.
  
  Fig 3: Inspecting Mirror Heater Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  HINT:
  
  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.

Fig 4: Preparing To Measure Voltage

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Inspect the voltage at the center of each heat wire.

Fig 5: Checking Voltage At Center Of Each Heat Wire

VOLTAGE & CRITERIA

Voltage	Criteria
Approx. 5 V	Okay (No break in wire)
Approx. 10 V or 0 V	Broken wire

HINT:

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.

Place the voltmeter positive (+) lead against the defogger positive (+) terminal.
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.
The point where the voltmeter deflects from zero to several V is the place where the heat wire is broken.

Fig 6: Identifying Broken Wire By Checking Voltage
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

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.

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 7: Repairing Broken Wire With Masking Tape
  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.