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Got the safety side of the NSS switch all set up and good - Red/blue chasers wires, 2 of them are all set and working - truck starts in park/N and not in any other gear. That leads me to 3 other wires on the connection plug. Reason I ask is this is a fresh wire - almost all wire was ripped out with only some connectors left - this happens to be the original connector and it has the 2 red/blue wires, it has 2 black/red chaser wires and 1 solid black wire. My question is does anyone else have this 5 wire combo and where do the 3 wires left go. I know at least 1 had to go to reverse lights, and my guess is there is an incoming reverse light power and then out wire to the lights so the 2 black/red chaser wires might make some sense - power in, power out but then what the heck does the solid black go to? is it one of Fords famous "not used wires"
Yeah same - I figured the two black/red would make the back up circuit - just no clue on the solid black. All the power from the backup lights must come from the red/blue and flow through the NSS - is that correct/
The back up lights and neutral/park interrupt functions are totally separate. They use their own separate contacts in the NSS. It is commonly known as a "Neutral Safety Switch" .... but it is really a "Combination Neutral Safety and Back Up Light Switch".
When the key is on Accy or Run, one of the red/black wires is hot. When the correct contacts are aligned in the NSS the current can the flow to the other red/black to find it's way to the back up light bulbs out back.
The red/blue wires are only used in the path to the starter relay, and only when their contacts are aligned in neutral or park (properly adjusted NSS), can current find it's way to the S on the starter relay when the key is turned to start.
When I accidently broke the flag that moves the pin of the NSS when replacing a cracked shift collar, I ran four wires from two simple toggle switches for a while and by flipping one to on, NU lights lit. By flipping the other, truck would start in any transmission position like P-R-N-3-2-1. After fixing the broke flag by snapping a new one in, I left my NSS bypass switches in place. I can use them like to illuminate the rear while hooking up a trailer, etc, or ... if that new flag broke, I could still start my truck.
Last edited by tbear853; Sep 28, 2025 at 03:14 PM.
Reason: add schematic
@tbear853 I could be reading your post incorrect. On my column mounted NSS I have 1 Red/blue chaser wire that comes from Ignition to the switch and 1 out to the starter exciter...that circuit works perfect/all aligned - I can only start in Park or Neutral. What I'm foggy on is where power comes from that provides the power for the reverse lights or does one of the Black/red wires connect up to a power source and the other out to the lights? Once I get that sorted, I still have no idea what that 5th (solid black) wire does since no one seems to have that. Truly cold be some later mod the owner did but it surely looks original.
@tbear853 I think I figured out the backup lights. In the kit I have, there should be a fuse box wire for 1 of the Black/red wires and the other out to the backup light - okay, that clears that up. Black wire - I'm just gonna tape that over. I did see somewhere that someone thought it could be related to a cruise control circuit but this truck is bare bones, there never would have been cruise on this. Again, its it 52 years of life, someone probably used some parts or modified something somewhere along the way - who knows.
On my '77, the back up light power comes from same 15A fuse as do turn signal flashers and the windshield washer pump. If key is off, no power through it.
Makes sense on the black wire.
Last edited by tbear853; Sep 29, 2025 at 08:49 AM.
Figured out that single orphaned black wire coming out of my NSS connector - camper reverse lights. I don't have the camper shell although I do suspect that maybe this truck did at one time as the top of my bed rails are total junk/rusted and bondo'd.
Figured out that single orphaned black wire coming out of my NSS connector - camper reverse lights. I don't have the camper shell although I do suspect that maybe this truck did at one time as the top of my bed rails are total junk/rusted and bondo'd.
Oh. you mean like a large slide in camper that would have blocked the bed back up lights? So, it has power when the trans is in reverse? Makes sense, I've read "speculation" it was a ground, or something dealing with CC?
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Makes sense, I've read "speculation" it was a ground, or something dealing with CC? 