Rear Window Defogger Circuit Check

WARNING: This page is about a different car, the 2004 Infiniti M45. However, it is still accessible from the selected car via links, so may be relevant.

REAR WINDOW DEFOGGER POWER SUPPLY CIRCUIT INSPECTION 1
1. Disconnect rear window defogger connector.
2. Turn ignition switch ON.
3. Push the rear window defogger switch.
4. Check voltage between rear window defogger connector and ground.
  
  Fig 1: Checking Rear Window Defogger Power Supply Circuit
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 2: Identifying Terminal Connector Voltage Specifications
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 2.
2. NG: GO TO 3 .
REAR WINDOW DEFOGGER GROUND HARNESS INSPECTION
1. Turn ignition switch OFF.
2. Check continuity between rear window defogger connector B421 terminal 1 (B) and ground.
  1. 1(B) - ground: Continuity should exist.
  Fig 3: Checking Rear Window Defogger Ground Harness
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: Rear window defogger circuit check is OK.
2. NG: Repair or replace harness between rear window defogger and ground.
REAR WINDOW DEFOGGER GROUND HARNESS INSPECTION 2
1. Disconnect condenser connector.
2. Turn ignition switch ON.
3. Push the rear window defogger switch.
4. Check voltage between condenser connector and ground.
  
  Fig 4: Checking Rear Window Defogger Ground Harness
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 5: Identifying Terminal Connector Voltage Specifications
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: Check the condenser
  - If condenser is OK, repair or replace harness between condenser and rear window defogger.
  - If condenser is NG, replace condenser.
2. NG: Repair or replace harness between rear window defogger and door mirror defogger relay and condenser.