Check Rear Window Defogger Switch Circuit

WARNING: This page is about a different car, the 2008 Infiniti FX45 and 2008 Infiniti FX35. However, it is still accessible from the selected car via links, so may be relevant.

CHECK REAR WINDOW DEFOGGER SWITCH OPERATION

With CONSULT-III

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

When rear window defogger switch is turned to ON

REAR DEF SW : ON

When ignition switch is turned to ON

IGN ON SW : ON

Without CONSULT-III

Turn ignition switch ON.
Check voltage between BCM connector ground.

Fig 1: Identifying Voltage Between BCM Connector Ground

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

REAR WINDOW DEFOGGER SWITCH OPERATION

Connector	Terminal (Wire color)		Condition	Voltage (V) (Approx.)
Connector	(+)	(-)	Condition	Voltage (V) (Approx.)
M3	9 (L/W)	Ground	Rear window defogger switch is pressed.	0
M3	9 (L/W)	Ground	Rear window defogger switch is OFF.	5

OK or NG

OK: Rear window defogger switch is OK.

NG: GO TO 2.

CHECK HARNESS CONTINUITY
1. Turn ignition switch OFF.
2. Disconnect BCM and A/C and AV switch connector.
3. Check continuity between BCM connector M3 terminal 9 and A/C and AV switch connector M64 terminal 16.
  9 (L/W) - 16 (L/W) : Continuity should exist.
  
  Fig 2: Identifying Continuity Between BCM Connector M3 Terminal 9 And A/C And AV Switch Connector M64 Terminal 16
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG

OK: GO TO 3.

NG: Repair or replace harness.
CHECK BCM OUTPUT SIGNAL
1. Connect BCM connector.
2. Turn ignition switch ON.
3. Check voltage between BCM connector M3 terminal 9 and ground.
  9 (L/W) - Ground : Approx. 5
  
  Fig 3: Identifying Voltage Between BCM Connector M3 Terminal 9 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG

OK: Replace A/C and AV switch.

NG: Replace BCM.