Check fuse under the hood of your truck (engine compartment), NOT under the dash.
Try bypassing the reverse light switch that plugs into the transmission. If your reverse lights come on, voila! Problem solved. Buy a new switch.
check for blown fuses
check reverse light switch on transmission.
the Nissan has 4 two very bright and two a little bit rubish but it is good to have i don't like Nissan but it has 4 ok!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
There is another fuse box under the hood and next to the battery. This fuse controls the horn, dashboard lights, and the tail lights.
I just had this problem on my 98 Frontier because the brake lights were staying on. I had to replace the brake light switch and the brake light button for it to go out.
check for blown light bulbs ,then check for broken wire at lights
Hopefully, you used a 12v. test light. Did you check the wiring and connections at the reverse light switch on the transmission. This could also be called the back up switch. There may be such a switch on the shift selector. Buy a Haynes or Chilton Total car care manuals.
To replace the taillights on a 2001 Nissan front first prop the hatch open. Locate the rear lights plastic housing and remove them to find the bulbs. Replace the bulbs.
Where is the fuse located for the reverse lights
Check your fuses
reverse/taillight fuse under driver side left fusebox panel