2. Check Harness Continuity

1. Turn ignition switch OFF.
2. Disconnect auto trunk control unit and auto trunk motor connector.
3. Check continuity between auto trunk control unit connector B110 terminal 14 and auto trunk motor connector B109 terminal 5.
   1. 14 (L/R) - 5 (L/R) : Continuity should exist  .
4. Check continuity between auto trunk control unit connector B110 terminal 14 and ground.
   1. 14 (L/R) - Ground : Continuity should not exist  .

OK or NG 

1. OK : Replace auto trunk control unit.
2. NG : Repair or replace harness between auto trunk control unit and auto trunk motor.

Fig 1: Checking Harness Continuity

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