I got a check engine light saying it was a transmission range sensor input aka neutral safety switch ive had this code now for a month and the car seems to run fine i hear when these go bad your car wont crank or start at all i havent had any of these issues but my car does have remote start which i installed way before this issue i dont know if thats the problem and my car is an automatic

 

The park/neutral switch does several things, not only keep the car from starting. It has the shift lever cable attached to it so you can but the transmission into the appropriate gear and it has a part that sends the position it is in back to the TCM. This is where you problem lies. The code is saying that the TCM is not getting this feedback. This means that downshifting will be effected, not sure about upshifting.

Maybe the park/neutral switch is bad, maybe the TCM is bad or maybe the wires between the 2 are damaged. You will have to troubleshoot this to figure out exactly what is wrong.

Here is a link to the service manuals for the Maxima. You didn't say what year, so I can't give you the exact link. The automatic transmission section is named AT.

http://boredmder.com/FSMs/Nissan/Maxima/

 

Its a 2002

 

And i installed a back up camera in my pioneer radio so i dont know if that caused a issue

 

The backup camera requires you to tap into the wire that says the transmission is in reverse. Check that wire tap that the wire didn't break.