Rear Window Defogger Switch Circuit Check

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

CHECK REAR WINDOW DEFOGGER SWITCH OPERATION
With CONSULT-II

Check ("REAR DEF SW", "IGN ON SW") in DATA MONITOR mode with CONSULT-II.

When rear window defogger switch is turned to ON

REAR DEF SW: ON

When ignition switch is turned to ON

IGN ON SW: ON

Fig 1: DATA MONITOR - CONSULT II Display Screen
Courtesy of NISSAN MOTOR CO., U.S.A.

With out CONSULT-II
1. Turn ignition switch ON.
2. Check voltage between BCM connector ground.
  
  Fig 2: Terminals Voltage Reference Chart
  Courtesy of NISSAN MOTOR CO., U.S.A.
  
  Fig 3: Checking Voltage Between BCM Connector Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: Rear window defogger switch check is OK.
- NG: GO TO 2.
CHECK REAR WINDOW DEFOGGER SWITCH CIRCUIT HARNESS CONTINUITY
1. Turn ignition switch OFF.
2. Disconnect BCM and unified meter and A/C amp.
3. Check continuity between BCM connector M18 terminal 9 and unified meter and A/C amp. connector M89 terminal 38.
  9 (W) - 38 (W): Continuity should exist .
4. Check continuity between BCM connector M18 terminal 9 and ground
  9 (W) - Ground: Continuity should not exist .
OK or NG
- OK: GO TO 3.
- NG: Repair or replace harness.
  
  Fig 4: Checking Rear Window Defogger Switch Circuit Harness Continuity
  Courtesy of NISSAN MOTOR CO., U.S.A.
CHECK BCM OUTPUT SIGNAL
1. Connect BCM.
2. Turn ignition switch ON.
3. Check voltage between BCM connector M18 terminal 9 and ground.
  9 (W) - Ground: Approx. 5
OK or NG
- OK: Replace unified meter and A/C amp.
- NG: Replace BCM. Refer to REMOVAL AND INSTALLATION OF BCM .
  
  Fig 5: Checking Voltage Between BCM Connector M18 Terminal 9 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.