Defogger System: Inspection

INSPECT DEFOGGER TIMER OPERATION
1. Connect the positive (+) lead from the battery to terminal 1, 8 and negative (-) lead to terminal 7.
  
  Fig 1: Inspecting Defogger Timer Operation
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Connect the positive (+) lead from the battery to terminal 5 through a 3.4 W test bulb.
3. Turn the defogger switch ON and check that the indicator light and test bulb light up for 12 for 18 minutes, then the indicator light and test bulb lights go out.
  If operation is not as specified, inspect the A/C amplifier.

Connector disconnected: INSPECT DEFOGGER SWITCH CIRCUIT

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

Fig 2: Identifying Defogger Switch Circuit Connector Terminal

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

CONNECTION CONDITION

Tester connection	Condition	Specified condition
1 - Ground	Ignition switch LOCK or ACC	No voltage
1 - Ground	Ignition switch ON	Battery positive voltage
7 - Ground	Constant	Continuity
8 - Ground	Constant	Battery positive voltage

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

INSPECT DEFOGGER RELAY CONTINUITY

Fig 3: Inspecting Defogger Relay Continuity

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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.

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, as shown.

Fig 4: Inspecting Defogger Wire Using Tester Wire
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.

Fig 5: Inspecting Voltage At Center Of Each Heat Wire

VOLTAGE CRITERIA

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

NOTE:

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.

Fig 6: Inspecting Voltage Of Broken Heat Wire
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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.
NOTE:
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.