2. Check Tail Lamp Relay Control Signal

WARNING: This page is about a different car, the 2004 Infiniti Q45. However, it is still accessible from the selected car via links, so may be relevant.

Turn ignition switch OFF.
Disconnect BCM connector.
Check voltage between BCM harness connector M4 terminal 3 (R/L) and ground.

Fig 1: Checking Tail Lamp Relay Control Signal

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

When lighting switch is 1ST or 2ND: Approx. 12V

When lighting switch is OFF: Approx. 0V

OK or NG

OK: Inspection end.
NG: Check harness for open or short between BCM and tail lamp relay.