Rear Window Defogger System Does Not Operate: Procedure

Fig 1: Identifying DEF, GAUGE And A/C Fuses

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the DEF, GAUGE and A/C fuses from the main body ECU.
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Item	Condition	Specified Condition
   DEF fuse	Always	Below 1 Ω
   GAUGE fuse	Always	Below 1 Ω
   A/C fuse	Always	Below 1 Ω

3. Reinstall the fuses.

NG → REPLACE FUSE 

OK: Go to next step 

Fig 2: Identifying N2 Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   N2-1 - Body ground	Ignition switch ON Rear defogger switch ON	11 to 14 V

NG → See step   4 

OK: Go to next step 

Fig 3: Identifying O8 Rear Window Defogger Wire Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the O8 rear window defogger wire connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   O8-1 - Body ground	Always	Below 1 Ω

3. Reconnect the rear window defogger wire connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   9 

Fig 4: Identifying N2 Rear Window Defogger Wire Connector Terminals

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the 4F main body ECU connector.
2. Disconnect the N2 rear window defogger wire connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   N2-1 - 4F-2	Always	Below 1 Ω
   N2-1 - Body ground	Always	10 kΩ or higher

4. Reconnect the main body ECU connector.
5. Reconnect the rear window defogger connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Disconnect the 4G main body ECU connector.
   Fig 5: Identifying 4G Main Body ECU Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the voltage according to the value(s) in the table below.

   Standard voltage

   Tester Connection	Switch Condition	Specified Condition
   4G-1 - Body ground	Ignition switch ON	11 to 14 V

3. Reconnect the main body ECU connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

Fig 6: Inspecting Main Body ECU (DEF Relay)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Remove the main body ECU.
2. Remove the GAUGE fuse from the main body ECU.
3. Measure the resistance of the DEF relay.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   4G-1 - 4F-2	When battery voltage absent	10 kΩ or higher
   4G-1 - 4F-2	When battery voltage applied to terminals 4Q-12 and GAUGE fuse (DEF relay side)	Below 1 Ω

4. Reinstall the fuse.
5. Reinstall the main body ECU.

NG → REPLACE MAIN BODY ECU 

OK: Go to next step 

1. Disconnect the G6 heater control connector.
   Fig 7: Identifying 4Q, 4S Main Body ECU Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the 4Q, 4S main body ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   G6-2 (RDEF) - 4Q-12	Always	Below 1 Ω
   G6-3 (IG+) - 4S-10	Always	Below 1 Ω
   G6-2 (RDEF) - Body ground	Always	10 kΩ or higher
   G6-3 (IG+) - Body ground	Always	10 kΩ or higher

4. Reconnect the heater control connector.
5. Reconnect the main body ECU connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Measure the resistance according to the value(s) in the table below.
   Fig 8: Identifying G6 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard resistance

   Tester Connection	Condition	Specified Condition
   G6-1 (E) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   10