Section 293 (Defogger System): Inspection

WARNING: This page is about a different car, the 2004 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT DEFOGGER SWITCH CIRCUIT

Disconnect the connector from the panel switch and inspect the connector on the wire harness side, as shown in Fig 1 .

Fig 1: Inspecting Defogger Switch Circuit

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

w/ Navigation:

SPECIFIED CONDITION TABLE (W/ NAVIGATION)

Tester connection	Condition	Specified condition
B12 (GND) - Ground	Constant	Continuity
B11 (+B) - Ground	Constant	Battery positive voltage
B22 (IG) - Ground	ignition switch LOCK or ACC	No voltage
B22 (IG) - Ground	Ignition switch ON	Battery positive voltage
A10 (RDFGR) - Ground	Constant	Battery positive voltage

w/o Navigation:

SPECIFIED CONDITION TABLE (W/O NAVIGATION)

Tester connection	Condition	Specified condition
16 (GND) - Ground	Constant	Continuity
8 (IG) - Ground	Ignition switch LOCK or ACC	No voltage
8 (IG) - Ground	Ignition switch ON	Battery positive voltage
2 (DEFC) - Ground	Constant	Battery positive voltage

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

INSPECT DEFOGGER RELAY CONTINUITY

SPECIFIED CONDITION TABLE (DEFOGGER RELAY CONTINUITY)

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.

Fig 2: Inspecting Defogger Relay Continuity

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

MIRROR HEATER RELAY:
INSPECT ENGINE ROOM R/B RELAY CIRCUIT

(See INSPECTION )

HINT:

The mirror heater relay is built in the engine room junction block. Also, the relay is constructed with a relay block that is in the junction block as a unit. To disconnect the wire harness connecting with relay block is impossible. If the relay has a malfunction, replace it with the junction block assembly wire harness together.

Fig 3: Identifying Mirror Heater Relay
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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 fingers, as shown in Fig 4 .

Fig 4: Inspecting Defogger Wire

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

Inspect the voltage at the center of each heat wire, as shown in Fig 5 .

VOLTAGE TABLE

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

Fig 5: Inspecting Voltage At Center Of Heat Wire

HINT:

If there is approximately 10 V, the wire is broken somewhere between the center of the wire and the positive (+) end. If there is no voltage, the wire is broken somewhere between the center of the wire and ground.

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

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

Fig 6: Measuring Voltage At Center Of Heat Wire
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

IF NECESSARY, REPAIR DEFOGGER WIRE
1. Clean the broken wire tips with grease, wax or 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 7: 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.
6. Do not repair the defogger wire for at least 24 hours.
  
  Fig 8: Applying Small Amount Of Agent To Wire
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
w/ Mirror heater:
INSPECT MIRROR HEATER OPERATION
1. Connect the battery positive (+) lead to terminal 5 and the battery negative (-) lead to terminal 12.
2. Check that the mirror becomes warm.
  HINT:
  
  It will take a short time for the mirror to become warm.
  
  Fig 9: Inspecting Mirror Heater Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002