Rear Window Defogger Switch Circuit Check

WARNING: This page is about a different car, the 2004 Nissan Quest. 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: Display CONSULT II (Data Monitor)

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

Without CONSULT-II

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

BCM CONNECTORS VOLTAGE

Connector	Terminal (Wire color)		Condition	Voltage (V) (Approx.)
	(+)	(-)
M18	9 (W/L)	Ground	Rear window defogger switch is pressed.	0
			Rear window defogger switch is OFF.	5

OK or NG

OK: Rear window defogger switch check is OK.
NG: GO TO 2.

Fig 2: Checking Voltage Between BCM Connectors And Ground

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

CHECK REAR WINDOW DEFOGGER SWITCH CIRCUIT HARNESS CONTINUITY
1. Turn ignition switch OFF.
2. Disconnect BCM and front air control.
3. Check continuity between BCM connector M18 terminal 9 and front air control connector M49 terminal 11
  1. 9 (W/L) -11 (W/L): Continuity should exist.
4. Check continuity between BCM connector M18 terminal 9 and ground
  1. 9 (W/L) - Ground: Continuity should not exist.
OK or NG
1. OK: GO TO 3.
2. NG: Repair or replace harness.
Fig 3: Checking Continuity Between BCM Connector M18 Terminal 9 And Front Air Control Connector M49 Terminal 11
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.
  1. 9 (W/L) - Ground: Approx. 5
  OK or NG
  1. OK: Replace front air control.
  2. NG: Replace BCM.
  Fig 4: Checking Voltage Between BCM Connector M18 Terminal 9 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.