Defogger System: Inspection

INSPECT DEFOGGER SWITCH CIRCUIT

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

Fig 1: Identifying Defogger Switch Connector On Wire Harness Side

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CHECKING DEFOGGER SWITCH CIRCUIT 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

CHECKING DEFOGGER SWITCH CIRCUIT 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

Fig 2: Identifying Defogger Relay Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

DEFOGGER RELAY CONTINUITY

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

If continuity is not as specified, replace the relay.

INSPECT ENGINE ROOM R/B RELAY CIRCUIT (See INSPECTION ).

Fig 3: Inspecting Engine Room R/B Relay Circuit
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

The mirror heater relay is built in 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 junction block assembly wire harness together.

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. See Fig 4.

Fig 4: Measuring Defogger Wire Voltage

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

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

Fig 5: Measuring Defogger Wire Voltage

DEFOGGER WIRE VOLTAGE

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.

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 6: Locating Broken Defogger Wire
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 voltage 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).
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.
W/ Mirror heater: INSPECT MIRROR HEATER OPERATION

Fig 9: Inspecting Mirror Heater Operation Connector Terminal
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. Connect the positive (+) lead from the battery to terminal 5 and the 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.