Okay, I wanted to add a camera to the AVIC-D3 I just installed, but wanted an easy way to hook the reverse signal wire. I found it.
If you have a factory hitch, this is pretty easy. The signal can be tapped from the relay harness behind the front passenger side kick panel. I have the 7 pin connector, not sure if it's the same for other styles. If you don't have the factory hitch, you can tap the main harness for the signal.
Location of the relay harness.
Another view, relays are just tucked in to place.
The lite blue with silver dash is the wire you want to tap. It's powered when you shift into reverse and the relay closes.
Location of the main harness connector. If you don't have the factory hitch, you should see a connector up behind the other relays and wiring. I still had the trailer relay harness plugged in in this pic.
Trailer relay harness unplugged and main harness connector rotated to look at the back of it. You want to tap the pink wire for the signal, the voltage out of this wire was 1 volt less than that of the relay wire. Notice the location of the stud that holds the kick panel in place.
Hope this helps anyone that didn't really want to string a wire all the way back to the tail lights just to get the reverse signal wire for their DVD/NAV system. Now I need to find a camera to hook up, I really don't like the look of Pioneer one.
This is on my 07, not sure if Nissan changed any of the wire colors, I know my 06 had this connector when I installed the relays, but couldn't tell you if the wires were the same color. I would recommend checking the wire you plan to use to see if it's only powered when the truck is on and in reverse.
If you have a factory hitch, this is pretty easy. The signal can be tapped from the relay harness behind the front passenger side kick panel. I have the 7 pin connector, not sure if it's the same for other styles. If you don't have the factory hitch, you can tap the main harness for the signal.
Location of the relay harness.

Another view, relays are just tucked in to place.

The lite blue with silver dash is the wire you want to tap. It's powered when you shift into reverse and the relay closes.

Location of the main harness connector. If you don't have the factory hitch, you should see a connector up behind the other relays and wiring. I still had the trailer relay harness plugged in in this pic.

Trailer relay harness unplugged and main harness connector rotated to look at the back of it. You want to tap the pink wire for the signal, the voltage out of this wire was 1 volt less than that of the relay wire. Notice the location of the stud that holds the kick panel in place.

Hope this helps anyone that didn't really want to string a wire all the way back to the tail lights just to get the reverse signal wire for their DVD/NAV system. Now I need to find a camera to hook up, I really don't like the look of Pioneer one.
This is on my 07, not sure if Nissan changed any of the wire colors, I know my 06 had this connector when I installed the relays, but couldn't tell you if the wires were the same color. I would recommend checking the wire you plan to use to see if it's only powered when the truck is on and in reverse.