Diagnostic Procedure

Symptom: Rear Window Defogger Does Not Activate, or Does Not Go Off After Deactivating. 

1. CHECK REAR WINDOW DEFOGGER OUTPUT SIGNAL 
   1. Turn ignition switch to ON position.
   2. Check voltage between time control unit harness connector M40 terminal 10 (G/R) and ground.

      Voltage (V) Approx.: 

      Rear window defogger switch is "OFF" :12V 

      Rear window defogger switch is "ON" :0V 

   OK or NG

   1. OK: Check the following.
      • Refer to "FILAMENT CHECK  ".
   2. NG: GO TO 2.
   Fig 1: Checking Rear Window Defogger Output Signal

   Courtesy of NISSAN MOTOR CO., U.S.A.
2. CHECK DEFOGGER RELAY COIL SIDE CIRCUIT 
   1. Disconnect time control unit harness connector M40.
   2. Turn ignition switch to ON position.
   3. Check voltage between time control unit harness connector M40 terminal 10 (G/R) and ground.

      Battery voltage should exist. 

   OK or NG

   1. OK: GO TO 3.
   2. NG: Check the following.
      • 10A fuse [No. 10, located in the fuse block (J/B)]
      • Rear window defogger relay
      • Harness for open or short between 10A fuse [No. 10, located in the fuse block (J/B)] and rear window defogger relay
      • Harness for open or short between rear window defogger relay and time control unit
   Fig 2: Checking Defogger Relay Coil Side Circuit

   Courtesy of NISSAN MOTOR CO., U.S.A.
3. CHECK REAR WINDOW DEFOGGER SWITCH INPUT SIGNAL 

   Check continuity between time control unit harness connector M40 terminal 3 (G/B) and ground.

   Continuity: Rear window defogger switch is pushed. Continuity should exist. 

   Rear window defogger switch is released. Continuity should not exist. 

   OK or NG 

   1. OK: GO TO 4.
   2. NG: Check the following.
      • Rear window defogger switch (Refer to "REAR WINDOW DEFOGGER SWITCH  ".)
      • Harness for open or short between time control unit and rear window defogger switch
      • Rear window defogger switch ground circuit
   Fig 3: Checking Rear Window Defogger Switch Input Signal

   Courtesy of NISSAN MOTOR CO., U.S.A.
4. CHECK POWER SUPPLY AND IGNITION INPUT SIGNAL 

   Check voltage between time control unit harness connector M40 terminals 7 (PU), 9 (G) and ground.

   TERMINAL VOLTAGE
   
   

   Terminals		Ignition switch position
   (+)	(-)	OFF	ACC	ON
   7	Ground	Battery voltage	Battery voltage	Battery voltage
   9	Ground	0V	0V	Battery voltage

   OK or NG 

   1. OK: GO TO 5.
   2. NG: Check the following.
      • 10A fuse [No. 10 or No. 13, located in the fuse block (J/B)]
      • Harness for open or short between time control unit and fuse
   Fig 4: Checking Power Supply And Ignition Input Signal

   Courtesy of NISSAN MOTOR CO., U.S.A.
5. CHECK TIME CONTROL UNIT GROUND CIRCUIT 

   Check continuity between time control unit harness connector M40 terminal 8 and ground.

   Continuity should exist. 

   Yes: Replace time control unit.

   No: Repair harness or connectors.

   Fig 5: Controlling Unit Ground Circuit

   Courtesy of NISSAN MOTOR CO., U.S.A.