Rear Window Defogger Circuit Check

WARNING: This page is about a different car, the 2004 Infiniti Q45. However, it is still accessible from the selected car via links, so may be relevant.

CHECK REAR WINDOW DEFOGGER POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect rear window defogger connector.
3. Turn ignition switch ON.
4. Check voltage between rear window defogger connector and ground.
  
  Fig 1: Voltage Specifications Between Rear Window Defogger Connector And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 2: Checking Voltage Between Rear Window Defogger Connector And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  OK or NG
  1. OK: GO TO 2.
  2. NG: GO TO 3 .
CHECK REAR WINDOW DEFOGGER GROUND HARNESS
1. Turn ignition switch OFF.
2. Check continuity between rear window defogger connector B421 terminal 1 and ground.
  1. 1 (B) - Ground: Continuity should exist
  OK or NG
  1. OK: Check filament, refer to "FILAMENT CHECK ".
    - If filament is OK, check the condition of the harness and the connector.
    - If filament is NG, repair filament.
  2. NG: Repair or replace harness between rear window defogger and ground.
Fig 3: Checking Continuity Between Rear Window Defogger Connector B421 Terminal 1 And Ground
Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK CONDENSER POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect condenser connector.
3. Turn ignition switch ON.
4. Check voltage between condenser connector and ground.
  
  Fig 4: Voltage Specifications Between Condenser Connector And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 5: Checking Voltage Between Condenser Connector And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  OK or NG
  1. OK: Repair or replace harness between condenser and rear window defogger.
  2. NG: GO TO 4.
CHECK CONDENSER HARNESS
1. Turn ignition switch OFF.
2. Disconnect rear window defogger and door mirror defogger relay connector.
3. Check continuity between condenser connector B25 terminal 1 and rear window defogger and door mirror defogger relay connector B8 terminal 7.
  1. 1 (L/R) - 7 (L/R): Continuity should exist.
  OK or NG
  1. OK: Check the condition of the harness and the connector.
  2. NG: Repair or replace harness condenser and rear window defogger and door mirror defogger relay.
Fig 6: Checking Continuity Between Condenser Connector B25 Terminal 1 And Rear Window Defogger And Door Mirror Defogger Relay Connector B8 Terminal 7
Courtesy of NISSAN MOTOR CO., U.S.A.