Rear Window Defogger System does not Operate: Procedure

PERFORM ACTIVE TEST USING TECHSTREAM (REAR WINDOW DEFOGGER WIRE)

Select the Active Test, use the Techstream to generate a control command, and then check the rear window defogger wire.

BODY NO. 4

Tester Display	Test Part	Control Range	Diagnostic Note
Rear Defogger	Operate rear window defogger wire	OFF or ON	-

Rear window defogger wire operates.

OK → REPLACE LUGGAGE ROOM JUNCTION BLOCK ASSEMBLY (LUGGAGE ROOM JUNCTION BLOCK ECU)

NG: Go to next step

INSPECT FUSE (DEFOG)
1. Remove the DEFOG M-fuse from the luggage room junction block.
2. Measure the resistance of the fuse.
  Standard resistance
  
  Below 1 Ω
NG → REPLACE FUSE

OK: Go to next step

INSPECT DEFOGGER RELAY (Marking: DEFOG)

Fig 1: Identifying Defogger Relay Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Remove the DEFOG relay from the luggage room junction block.

Measure the resistance of the relay.

Standard resistance

Tester Connection	Specified Condition
3 - 5	10 kΩ or higher
3 - 5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

NG → REPLACE DEFOG RELAY

OK: Go to next step

CHECK WIRE HARNESS (LUGGAGE ROOM JUNCTION BLOCK - BATTERY)

Disconnect the 6L junction block connector.

Fig 2: Identifying Wire Harness Side
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the voltage of the wire harness side connector.

Standard voltage

Tester Connection	Specified Condition
6L-1 - Body ground	10 to 14 V

NG → REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to next step

CHECK WIRE HARNESS (LUGGAGE ROOM JUNCTION BLOCK - REAR WINDOW DEFOGGER WIRE)

Fig 3: Identifying Luggage Room Junction Block Connector Terminals And Rear Window Defogger Wire Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Disconnect the 6D junction block connector.
Disconnect the R12 defogger connector.

Measure the resistance of the wire harness side connectors.

Standard resistance

Tester Connection	Specified Condition
6D-1 - R12-1	Below 1 Ω
6D-1 or R12-1 - Body ground	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to next step

CHECK WIRE HARNESS (REAR WINDOW DEFOGGER WIRE - BODY GROUND)

Disconnect the R13 defogger connector.

Fig 4: Identifying R13 Defogger Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Measure the resistance of the wire harness side connector.

Standard resistance

Tester Connection	Specified Condition
R13-1 - Body ground	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS AND CONNECTOR

OK: Go to next step

INSPECT REAR WINDOW DEFOGGER WIRE

Fig 5: Pressing Foil Against Wire

NOTE:

When cleaning the glass, wipe the glass along the wire using a soft and dry cloth. Take care not to damage the wires.
Do not use detergents or glass cleaners that have abrasive ingredients.
When measuring voltage, wrap a piece of tin foil around the tip of the negative tester probe and press the foil against the wire with your finger, as shown in the illustration.

Turn the ignition switch ON.

Fig 6: Measuring Voltage Center Of Defogger Wire
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Turn the defogger switch ON.

Measure the voltage at the center of each defogger wire as shown in the illustration.

Standard voltage

Voltage	Criteria
Approx. 5 V	Wire is not broken
Approx. 10 or 0 V	Wire is broken

HINT:

If there is approximately 10 V, the wire may be faulty between the center of the wire and the wire end on the battery side. If there is no voltage, the wire may be faulty between the center of the wire and the wire end on the ground side.

Fig 7: Measuring Voltage Between Center Of Wire And Wire End On Ground Side

Place the voltmeter's positive (+) lead against the defogger wire on the battery side.
Place the voltmeter's negative (-) lead with the foil strip against the wire on the ground side.
Slide the positive (+) lead from the battery side to the ground side.
The point where the voltage drops from approximately 10 V to 0 V is where the defogger wire is broken.
HINT:

If the defogger wire is not broken, the voltmeter should indicate 0 V at the positive (+) end of the defogger wire. The voltage gradually increases to approximately 12 V as the lead moves to the other end.

NG → REPAIR REAR WINDOW DEFOGGER WIRE

OK: Go to next step

CHECK OPERATION OF A/C AMPLIFIER ASSEMBLY
1. After replacing the A/C amplifier with a new one, check that the rear defogger operates normally.
  OK
  
  Rear defogger operates normally.
NG → GO TO LUGGAGE ROOM JUNCTION BLOCK ECU POWER SOURCE CIRCUIT

OK → END (A/C AMPLIFIER ASSEMBLY DEFECTIVE)