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How does the neutral safety switch work?

19K views 12 replies 6 participants last post by  HwyStarJoe 
#1 ·
How does the reverse light/neutral safety switch work? I don't really care about the NSS, but would like the backup lights to work.

Floor shifted, was a TH350, now a 4L80e, with a horseshoe shifter. I replaced the shift plate with a shift works shifer, and now no backup lights.
My backup lights will come on when I jump the pink and green wires, so I know it is working properly. However, the shifter won't make the swith work.

I have looked at it and can't figure out for the life of me how the switch is supposed to "know" what position the shifter is in. How do these things work?
 
#2 · (Edited)
Any photos of what you have in place? Hard to say what you have with a non standard plate. I have no knowledge of a shift works plate but there must be a place to mount a set of switches.

In theory the reverse switch is positioned so that when the shifter is in the reverse position the backup light circuit is switched on. On a manual vehicle these are driven by the steering column sleeve being rotated by the rod coming from a bellhousing crank that is driven from the reverse lever of the manual transmission. Vehicles with aftermarket headers often have to remove the rod, so a reverse switch is mounted on either the shifter being pushed by the reverse lever, or connected to the transmission reverse lever. Hurst makes a very popular switch for their competition plus line of shifters.

The neutral safety switch on an manual looks for the clutch position. In an automatic it looks for either neutral or park positions before the ignition can crank.
 
#3 ·
The switch is already installed and is located on the right hand side of the shifter in the stock position.

My question is how does the shifter know what position you are in? Does the horseshoe contact the switch in some way? There is a white "tab" below the switch, but pressing it or moving it does not help me, and the horseshoe does not touch it. Nothing seems to activate the switch itself.
 
#6 ·
Ah sorry I missed your model number http://www.shiftworks.com/4lx.htm covers the 4L80e. The switch is not on the shifter but actually on the side of the transmission where the cable attaches. Sorry for the confusion. Too tired to be reading without my glasses.
 

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#7 ·
Brian you're not understanding me. I am well aware of the switch on the 4l80e on the tranny. I'm asking how the one on the shifter works. Forget that I have a 4l80e or a new detent plate. How does the switch work on a TH350 with a horseshoe shifter on a 68? If you don't know it's OK, maybe someone else can help.
 
#8 · (Edited)
How does the switch work on a TH350 with a horseshoe shifter on a 68?
Ryan the horseshoe floor shifter has a bracket on the passenger side of the handle (ringed in red on the attached photo) that mounts on the end of the pivot shaft and engages the movable tab on the underside of the NSS. The NSS is in a fixed position on the shifter baseplate, but as the shifter handle moves through it's arc, it in turn activates the movable part of the switch from below and turns on the backup (reverse) lights when in 'R' position.
 
#9 ·
here is pic of my 69 shifter, the brass tabs are visibile that the harness plugs into. Im guessing 68 is very similar if not the same. I have the 700r tranny but this neutral/backup switch works great. :)

 
#10 ·
Tim explained it best....
The fixed tab on the shifter handle fits INSIDE the NSS in a slot. Sort of like how the ignition switch is actuated by the rod on the column.
As the shifter is moved, it moves a slider inside the NSS to change the contact points inside, actuating the different functions. The switch is adjustable on the shifter. If you're having trouble getting it to start for example, or not actuating the Reverse lights, have someone stand behind the car as a spotter as you adjust the switch and move the shifter.
And make sure you've got the green and pink wires in the right positions.
 
#11 · (Edited)
Hopefully these are views to help you see. The white plastic protrusion on the bottom of the switch fits into the slot you see in the second picture. The switch is affixed to the shifter base - the white deal moves inside the switch.. To adjust, leave the mount screws loose. Shift the trans into reverse, then slide the switch on its slotted mounting holes until the backup lights come on, then tighten the screws. Check for ability to start in Park and in Neutral, and inability to start in all other gears.

If the white part on your switch doesn't fit snugly into the u-shaped slot you might have a switch intended for use on a column mounted shifter.

Not that it matters - but this is the stock switch on a shifter modified with a shiftworks plate for a 2004R/700R4





 
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