Section 365 (Defogger System): Inspection

WARNING: This page is about a different car, the 2004 Lexus GS 430 and 2004 Lexus GS 300. 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 voltmeter to terminal 6 of body ECU No. 1 connector and negative (-) lead to body ground.
2. When the switch is OFF, the voltage should be approx. 12V.
  
  Fig 1: Connecting Positive Lead From Voltmeter To Terminal 6 Of Body ECU No. 1 Connector
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Turn the defogger switch ON and check that the indicator lights up and that the voltage is less than 1 V.
4. After 15 minutes, check that the switch is OFF and the voltage is approx. 12 V.
If operation is not as specified, replace the switch.

Fig 2: Locating Indicator
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Connector disconnected: INSPECT DEFOGGER SWITCH (in A/C control assembly) CIRCUIT

Disconnect the connector from the A/C control assembly and inspect the connector on wire harness side, as shown in the chart.

Fig 3: Inspecting Connector On Wire Harness Side

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TESTER CONNECTION SPECIFICATION

Tester connection	Condition	Specified condition
B10 - Ground	Constant	Continuity
A1 - Ground	Constant	Battery voltage
A2 - Ground	Ignition switch LOCK	No voltage
A2 - Ground	Ignition switch ACC or ON	Battery voltage

If the circuit is not as specified, replace the switch.

INSPECT DEFOGGER RELAY CONTINUITY

TESTER CONNECTION SPECIFICATION

Condition	Tester connection	Specified condition
Constant	1 - 2	Continuity
Apply B+ between terminals 1 and 2.	3 - 5	Continuity

If continuity is not as specified, replace the relay.

INSPECT DEFOGGER RELAY CIRCUIT (See REAR DEFOGGER RELAY CIRCUIT and INSPECTION )

Fig 4: Inspecting Defogger Relay Continuity
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INSPECT MIRROR DEFOGGER RELAY CONTINUITY

TESTER CONNECTION SPECIFICATION

Condition	Tester connection	Specified condition
Constant	1 - 2	Continuity
Apply B+ between terminals 1 and 2.	3 - 5	Continuity

If continuity is not as specified, replace the relay.

INSPECT MIRROR DEFOGGER RELAY CIRCUIT (See INSPECTION )

Fig 5: Inspecting Mirror Defogger Relay Circuit
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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, wrap a piece of tin foil around the tip of the negative probe and press the foil against the wire with your finger, as shown.

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

Inspect the voltage at the center of each heat wire, as shown.

Fig 6: Inspecting Defogger Wire

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VOLTAGE CRITERIA

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

Fig 7: Inspecting Voltage At Center Of Heat Wire

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 battery to ground side.
The point where the voltmeter deflects from several V to zero V is the place where the defogger wire is broken.

Fig 8: Placing Voltmeter Negative Lead With Foil Strip Against Wire On Ground Side

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 moves 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 for repair.
3. Thoroughly mix the repair agent (DuPont paste No. 4817).
  
  Fig 9: Placing Masking Tape Along Both Sides Of Wire For Repair
  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.
6. Do not repair the defogger wire for at least 24 hours.
  
  Fig 10: Applying Small Amount Of Agent To Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
w/ Mirror heater (w/o Driving position memory):
INSPECT MIRROR DEFOGGER OPERATION
1. Connect the positive (+) lead from the battery to terminal 7 and the negative (-) lead to terminal 8.
2. Check that the mirror becomes warm.
HINT:

It will take a short time for the mirror to become warm.

Fig 11: Connecting Positive Lead From Battery To Terminal 7 And Negative Lead To Terminal 8
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
w/ Mirror heater (w/ Driving position memory):
INSPECT MIRROR DEFOGGER OPERATION
1. Connect the positive (+) lead from the battery to terminal 12 and the negative (-) lead to terminal 13.
2. Check that the mirror becomes warm.
HINT:

It will take a short time for the mirror to become warm.

Fig 12: Connecting Positive Lead From Battery To Terminal 12 And Negative Lead To Terminal 13
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002