WARNING: This page is about a different car, the 2005 Infiniti G35. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Troubleshooting Chart - Overheating Cause Analysis (1 of 2)
Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: Troubleshooting Chart - Overheating Cause Analysis (2 of 2)