Talk to me about the neutral safety switch....

[Chrispbrown36]

Today I got motivated to see why my reverse lights weren't working on my 87 V10. Traced the wiring and there is no obvious breaks anywhere. Pulled the neutral safety switch and I am assuming that it is the problem, but I have a few questions. First of all, only the prongs for the reverse lights had anything plugged into it. There are three pairs of prongs on there. The one on the truck had the center pair of prongs bent and broken off. Should something be plugged up on the other two sets of prongs? I didn't see any loose connectors hanging around and, until I started messing around with it, everything but the reverse lights worked. Which brings me to my next question. After messing around with it I popped the old switch back in place and plugged it back up. I towed my boat trailer down to a neighbors house for him to weld something for me. As I was leaving I noticed I had no brake lights, running lights, and still no reverse lights. Do all the lights run through this switch or did I screw something up elsewhere?

[Chrispbrown36]

Bump

[Chrispbrown36]

The brake and turn signal issue is fixed, but I still have no reverse lights. I put in a new AC Delco neutral safety switch and still nothing. After doing some looking around I finally found an old post (http://67-72chevytrucks.com/vboard/s...d.php?t=524380) about an 82 C10 that shows there being two plugs plugged into the NSS. From what I can tell, I have the plug for the neutral safety but not the plug for the reverse lights.

The two pictures are from the old post. The first shows the NSS on the 85. The plug with the two purple wires going into it on the left are the ones I have, only mine are orange/black and black/white. The center plug is with the green and blue wires is the one I am missing that I believe are for the reverse lights.
The second picture is an isolation of the wiring diagram for the switch. I might be reading this wrong, but it looks like the blue and green wire come from the back up light switch to the NSS. I am confused by this because everything I can find says that only manual transmissions have a back up light switch, but the diagram shows that they are for automatic transmissions. What am I missing here?

[Dead Parrot]

It makes sense that the auto would get the reverse light signal from the NSS since it is already detecting Park & Neutral. Not much to add a set of contacts for reverse to light up the backup lights.

Guessing a manual has a separate backup switch either in the trans or somehow rigged to the shifter or linkage.

Checked the NSS on my 75 with a TH350. Has a different plug then the one pictured but does have the same 4 wires with similar colors.

[Chrispbrown36]

Yes, the manual has a switch on the trans. My problem is that the wires I need for the reverse lights are no where to be found. I can find no wires that are just hanging, which I would assume they should be.

[jimmyjammoto]

If I'm not mistaken you have the blue and green wires swapped.

[jimmyjammoto]

You can also adjust that switch by ratcheting it left and right. Chock wheels, set parking brake and put in reverse. Ratchet assembly until lights come on.

[Tony_W]

Originally Posted by Chrispbrown36

Yes, the manual has a switch on the trans. My problem is that the wires I need for the reverse lights are no where to be found. I can find no wires that are just hanging, which I would assume they should be.

What you have looks to be correct as in the switch itself.

Basically two plugs on there.

The top middle is your reverse lights. Power going in and power going to lights. On your reverse lights, you don't find wires, so I'd look at my outside wires on the reverse lights and trace back to fuse box, match color, might be a stripe color difference, post pic what you find.

The left plug is power in from key ignition and power out to starter solenoid.

There could be a chance, your two wires you have are for reverse plug and someone bypassed your NSS to the starter. What color is actually on your back up light wire will help confirm this.

I do not have a manual on your truck to help on this, but hope it helps ya.