Rear Window Defogger System does not Operate: Procedure

1. Check that the engine starts normally.

   OK

   Engine starts normally.

NG → See step   11 

OK: Go to next step 

1. Select the Active Test, using the Techstream to generate a control command, and then check that the rear window defogger operates.
   AIR CONDITIONER
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Defogger Relay (Rear)	Rear window defogger relay operation	OFF/ON	-

   RESULT
   
   

   Result	Proceed to
   Rear window defogger operates normally (w/ Display and Navigation Module Display)	A
   Rear window defogger operates normally (w/o Display and Navigation Module Display)	B
   Rear window defogger does not operate	C

B → See step   4 

C → See step   5 

A: Go to next step 

1. Temporarily replace the display and navigation module display with a new or normally functioning one. Refer to REMOVAL .
2. Check that the malfunction disappears.

   OK

   Malfunction disappears.

   RESULT
   
   

   Result	Proceed to
   OK (w/o Navigation System)	A
   OK (w/ Navigation System [for HDD])	B
   OK (w/ Navigation System [for DVD])	C
   NG	D

B → See step   17 

C → See step   13 

D → See step   12 

A → See step   16 

1. Temporarily replace the integration control and panel with a new or normally functioning one. Refer to REMOVAL .
2. Check that the malfunction disappears.

   OK

   Malfunction disappears.

NG → See step   12 

OK → See step   15 

1. Remove the DEFOG H-fuse from the engine room No. 1 relay block.
2. Remove the D-IG1-3 fuse from the main body ECU.
3. Measure the resistance of the fuses.
   STANDARD RESISTANCE
   
   

   Tester Connection	Condition	Specified Condition
   DEFOG H-fuse	Always	Below 1 Ω
   D-IG1-3 fuse	Always	Below 1 Ω

NG → REPLACE FUSE 

OK: Go to next step 

Fig 1: Inspecting Defogger Relay (Marking: Defog)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the defogger relay from the relay block No. 3.
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   3 - 4	When battery voltage is not applied between terminals	Below 1 Ω
   3 - 5	When battery voltage is not applied between terminals	10 kΩ or higher
   3 - 4	When battery voltage is applied to terminals 1 and 2	10 kΩ or higher
   3 - 5	When battery voltage is applied to terminals 1 and 2	Below 1 Ω

NG → REPLACE DEFOGGER RELAY 

OK: Go to next step 

Fig 2: Identifying A51 Front Light ECU Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the defogger relay from the No. 3 relay block.
2. Disconnect the A51 front light ECU connector.
3. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   Defogger relay terminal 2 - Body ground	Engine switch on (IG)	11 to 14 V
   Defogger relay terminal 5 - Body ground	Always	11 to 14 V

4. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   Defogger relay terminal 1 - A51-12 (RDEF)	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

Fig 3: Identifying S19 And W1 Defogger Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the S19 and W1 defogger connectors.
2. Disconnect the defogger relay from the No. 3 relay block.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   S19-1 - Defogger relay terminal 3	Always	Below 1 Ω
   W1-1 - Body ground	Always	Below 1 Ω
   Defogger relay terminal 4 - Body ground	Always	Below 1 Ω
   S19-1 - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Turn the engine switch on (IG).
2. Turn the defogger switch ON.
3. Check the voltage at the center of each defogger wire as shown.
   Fig 4: Identifying Voltage At Center Of Defogger Wire Using Voltmeter

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   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.

   NOTE: 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.
4. Place the voltmeter's positive (+) lead against the defogger wire on the battery side.
   Fig 5: Placing Voltmeter's Positive (+) Lead Against Defogger Wire On Battery Side

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
5. Place the voltmeter's negative (-) lead with the foil strip against the wire on the ground side.
6. Slide the positive (+) lead from the battery side to the ground side.
7. 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 and gradually increase to approximately 12 V as the meter probe is moved to the other end.

NG → See step   14 

OK: Go to next step 

1. Temporarily replace the front light ECU with a new or normally functioning one.
2. Check that the malfunction disappears.

   OK

   Malfunction disappears.

NG → See step   12 

OK → REPLACE FRONT LIGHT ECU