Rear Window Defogger System Does Not Operate: Wiring Diagram

1. Check that the engine starts normally.

   OK: Engine starts normally. 

NG : GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START 

OK : GO TO NEXT STEP 

1. Using the intelligent tester ACTIVE TEST, generate a control command and then check that the rear window defogger operates.

   A/C amplifier assembly (A/C ECU) 

   ITEM TESTER DIAGNOSIS CHART
   
   

   Item	Test Details	Diagnostic Note
   DEFOGGER RLY-R	Operate rear window defogger OFF/ON	-

   Result 

   RESULT PROCEDURE CHART
   
   

   Result	Proceed to
   Rear window defogger operates normally	A
   Rear window defogger operates abnormally	B

B : Go to step   4 

A : GO TO NEXT STEP 

1. Temporarily replace the multi-display with a new or normally functioning one.
2. Check that the malfunction disappears.

   OK: Malfunction disappears. 

NG : REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY 

OK : REPLACE MULTI-DISPLAY 

1. Remove the DEFOG, ALT, LH J/B-AM and RH J/B-B fuses from the engine room No. 1 relay block.
2. Remove the AM2 fuse from the cowl side junction block RH.
3. Remove the LH-IG fuse from the cowl side junction block LH.
4. Measure the resistance of the fuses.

   Standard resistance: Below 1 Ω 

NG : REPLACE FUSE 

OK : GO TO NEXT STEP 

1. Remove the DEFOG relay from the engine room No.1 relay block.
2. Measure the resistance of the relay.

   Standard resistance 

   Fig 3: Measuring Resistance Of Relay

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TESTER CONNECTION SPECIFICATION
   
   

   Tester Connection	Specified Condition
   3 - 4	Below 1 Ω
   3 - 5	10 kΩ or higher
   3 - 5	Below 1 Ω (when battery voltage is applied to terminals 1 and 2)

NG : REPLACE RELAY 

OK : GO TO NEXT STEP 

1. Remove the DEFOG relay from the engine room No. 1 relay block.
2. Disconnect the A7 ECM connector.
3. Measure the voltage of the wire harness side connectors.

   Standard voltage 

   Fig 4: Measuring Voltage Of Wire Harness Side Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   TESTER CONNECTION SPECIFICATION
   
   

   Tester Connection	Condition	Specified Condition
   Relay block DEFOG relay terminal 1 - Body ground	Engine switch on (IG)	10 to 14 V
   R/B DEFOG relay terminal 5 - Body ground	Always	10 to 14 V

4. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   TESTER CONNECTION SPECIFICATION
   
   

   Tester Connection	Condition	Specified Condition
   Relay block DEFOG relay terminal 2 - A7-13 (RDEF)	Always	Below 1 Ω

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

OK : GO TO NEXT STEP 

1. Disconnect the U20 and V20 defogger connectors.
2. Disconnect the DEFOG relay from the engine room No.1 relay block.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   TESTER CONNECTION SPECIFICATION
   
   

   Tester Connection	Specified Condition
   V20-1 - Relay block DEFOG relay terminal 3	Below 1 Ω
   U20-1 - Body ground	Below 1 Ω
   Relay block DEFOG relay terminal 4 - Body ground	Below 1 Ω

   Fig 5: Measuring Resistance Of Wire Harness Side Connectors

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : REPAIR OR REPLACE HARNESS AND 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 in the illustration.

   Standard voltage 

   VOLTAGE SPECIFICATION
   
   

   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 in the illustration.
   Fig 6: Identifying Voltage At Center Of Each Defogger Wire

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
4. Place the voltmeter's positive (+) lead against the defogger wire on the battery side.
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 but gradually increases to approximately 12 V as the meter probe is moved to the other end.

   Fig 7: Identifying Defogger Wires For Breaks

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : REPAIR REAR WINDOW DEFOGGER WIRE 

OK : GO TO NEXT STEP 

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

   OK: Malfunction disappears. 

NG : REPLACE A/C AMPLIFIER ASSEMBLY (A/C ECU) 

OK : REPLACE ECM