Check Key Switch (BCM Input)

WARNING: This page is about a different car, the 2006 Infiniti G35. However, it is still accessible from the selected car via links, so may be relevant.

CHECK KEY SWITCH POWER SUPPLY CIRCUIT
1. Turn ignition switch OFF.
2. Disconnect key switch and ignition knob switch connector.
3. Check voltage between key switch and ignition knob switch harness connector M310 terminal 3 and ground.
  3 (Y) - Ground : Battery voltage.
  
  Fig 1: Identifying Voltage Between Key Switch And Ignition Knob Switch Harness Connector M310 Terminal 3 And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: GO TO 2.
- NG: Check harness between key switch and ignition knob switch and fuse.

CHECK KEY SWITCH

Check continuity between key switch and ignition knob switch harness connector M310 terminals 3 and 4.

TERMINALS CONTINUITY REFERENCE

Connector	Terminal		Condition	Continuity
M310	3	4	Insert mechanical key into ignition switch.	Yes
M310	3	4	Remove mechanical key from ignition switch.	No

Fig 2: Identifying Continuity Between Key Switch And Ignition Knob Switch Harness Connector M310 Terminals 3 And 4

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

OK or NG

OK: GO TO 3.
NG: Replace key cylinder assembly (built-in key switch).

CHECK KEY SWITCH SIGNAL CIRCUIT
1. Disconnect BCM connector.
2. Check continuity between BCM harness connector M1 terminal 37 and key switch and ignition knob switch harness connector M310 terminal 4.
  37 (B/P) - 4 (B/P) : Continuity should exist.
3. Check continuity between BCM harness connector M1 terminal 37 (B/P) and ground.
  37 (B/P) - Ground : Continuity should not exist.
  
  Fig 3: Identifying Continuity Between BCM Harness Connector M1 Terminal 37 (B/P) And Ground
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
- OK: Key switch (BCM input) circuit is OK.
- NG: Repair or replace harness between key switch and ignition knob switch and BCM.