I need to understand how the neutral switch works the backup lights

Did you check the backup light switch ?

well dont worry,if your backup lights work,you dont need a reverse light

if the backup bulbs are good then check the neutral switch as this is where the reverse switch is, its part of the neutral switch. it may have stopped working and need replacing. you will be replacing the neutral switch. if you have power out of the switch then check for power and ground at the light socket as there could be a bad wire or connection.

The neutral safety switch which also powers the backup lights is a black switch mounted on a metal plate, so I would guess it is mounted to the shifter or the transmission. If you have a column shift check the bottom of the column, if it is in the console look around near the shifter.
Otherwise it would be on the transmission near the shift lever.

Hi...sounds like your Neutral Safety Switch needs to be adjusted. Loosen screws enough to slide switch one way or the other until your backup lights go out when the vehicle is in park, then re-tighten screws. Check to make sure backup lights come on only in Reverse. Here is a link showing the location of your Neutral Safety Switch: http://www.autozone.com/autozone/parts/1992-Buick-Roadmaster/Neutral-Safety-Switch/_/N-iwj89Z9cid6 (copy and paste entire link into your browser if the link is not live)

Ford Neutral Safety Switch; Ford Reverse Light Switch; Backup Light Switch.

The Neutral Safety Switch wires in my 1971 Ford F100 are orange with a blue stripe.
The Reverse, or Backup Light Switch wires are black with a red stripe.

There are two sets of two wires across this combined neutral safety and backup light switch, for a total of 4 wires. Photos are at the end of this post.

The switch for the 1971 Ford F100 pickup truck is the same as in many other years and models. For details, including parts numbers, see the following quote from an expert at Ford Truck Enthusiasts:
http://www.ford-trucks.com/forums/287185-back-up-light-and-neutral-safety-switch-2.html#post5601846

The neutral switch also controls the backup lights, and is the same 1967/77.

C7TZ-7A247-A .. Neutral/Backup Switch (Motorcraft SW-600)

There is no separate backup light switch..except on 1967/68 F350's.

Neutral switch location 1967/77:

The plastic half moon shaped neutral safety switch mounts on the outside lower portion of the steering column (NOT on the transmission!).

It's activated by an inverted Y shaped lever that snaps on the shift tube

D0TZ-7B097-B .. Lever, Neutral Switch Actuator = From FTE sponsor DIRECT FORD PARTS: Ford suggested retail price: $18.72 / FTE member net: $13.23.

The switch is also still available from Ford, but the website is down so I can't post the list & net prices. .

1978 is the FIRST year the F100/350's have the neutral switch mounted on the transmission. __________________

Bill // Retired Ford Parts Manager // SoCal Chapter member // Part Number Research: 1928/2001 FoMoCo vehicles.

IMAGES

Driver side of the neutral / reverse switch showing the travel slot for the switch arm, the return tensioning spring, and the arm.


The front, steering wheel side of the neutral / reverse switch after removal from the steering column. The switch's two functions are actuated when the lever in the column moves the switch lever shown here to different positions as gears are selected.


The neutral switch is installed on the steering column near the firewall, with 5/8" bolts into the steering column (visible hole) and down column from a rectangular opening in the column housing. The actuating lever for the switch is attached to the gear shift shaft inside the housing; the lever is visibly protruding from the opening in this image.


Back of neutral / reverse switch, showing the wiring attachments. Black with red stripe is the backup light wiring, Orange with blue stripe is the neutral safety switch, it prevents starting in gears other than neutral & park.

You do know your backup lights work in conjunction with safety neutral switch/backup switch on transmission right?

The neutral safety switch can be adjusted to make this work. (loosen it and turn , then lock it down. This changes neutral start position as well so make sure both work when you're finished! Switch is on right side of trans. Switch is about $220 so don't break it!

I had the same problem. My backup lights wouldn't come on in when I put the auto. trans. shifter into the Reverse position. They WOULD come on briefly as I moved the shifter from Park position into Reverse, but would go off again when the shifter reached the Reverse detent. I got the solution from the Haynes service manual, in which the relevant switch is referred to as something like the neutral safety switch. Check on top of the steering column close to the firewall. Set the parking brake, then move the auto. trans. shifter into Neutral position. Get under the dash and rotate the neutral safety switch clockwise as far as it will go. Then move the shifter into the Park position, and your switch should be set. If the backup lights don't come on now when the shifter is put into Reverse position with the ignition switch 'on', there may be another problem.

Your post is really difficult to understand, but I think you are likely looking for the neutral safety switch (which generally also is part of the backup light system)
So, if I read it right, find that switch and you have found your problem.