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3 prong reverse and neutral safety switch harness

Kevin Burdette

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I was just wondering if anyone had pictures of the 3 prong neutral safety switch harness and how it plugs up into the firewall harness. I have a 70 coronet so I assume anyone with a 69-70 b body would have the same set up. Thanks in advance.
 
The NSS doesn't plug into any harness. The brown wire attaches to the bottom right spade terminal on the starter relay on your firewall. It's the terminal marked either G or GRD. It's opposite the yellow wire terminal. The 3 prong plugs into the neutral safety switch, which is screwed into the passenger side of the transmission.
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The NSS doesn't plug into any harness. The brown wire attaches to the bottom right spade terminal on the starter relay on your firewall. It's the terminal marked either G or GRD. It's opposite the yellow wire terminal.
View attachment 1552055
But which terminals on the plug go to where? I think that's what the OP is asking.
 
The NSS doesn't plug into any harness. The brown wire attaches to the bottom right spade terminal on the starter relay on your firewall. It's the terminal marked either G or GRD. It's opposite the yellow wire terminal. The 3 prong plugs into the neutral safety switch, which is screwed into the passenger side of the transmission.
View attachment 1552055
I have the box set up but there is no separate harness that plugs into the 3 prong switch for my reverse lights on the transmission. Ill send a pic of that too.

IMG_3214.jpeg
 
I know there is a separate harness for this switch but I can’t find anywhere oine where it plugs into on the firewall

IMG_3215.jpeg
 
The brown wire just plugs directly to the starter, there isn’t any other wire connected to it.
That's the larger, 12 ga wire that is held down with a screw, directly in the middle of the starter relay. The smaller, brown wire in the bottom right of your relay should go to a circular, 3 prong female terminal that plugs into the NSS. It's possible that a previous owner could have cut the wire and grounded it somewhere to the firewall. Your car would still start, but the neutral safety would be defeated.
 
I found this online, says its for 69-70 b body reverse light/NSS for automatic transmissions. It includes 70 Chargers and every Coronet model with big block.

View attachment 1552067
That's it. I have a 69 Coronet which doesn't have that additional plug at the bottom of your pic. It's probably a 70 and later safety feature.
 
I just need to know where it plugs into on the firewall. That L-shaped plug in is throwing me off big time.
The L plug is what goes to the lower right terminal on the starter relay. Pull off the female terminal that's on there now. While its off you might as well trace to see where it goes. Lots of wiring hacks on these old cars.
 
That's it. I have a 69 Coronet which doesn't have that additional plug at the bottom of your pic. It's probably a 70 and later
The L plug is what goes to the lower right terminal on the starter relay. Pull off the female terminal that's on there now. While its off you might as well trace to see where it goes. Lots of wiring hacks on these old cars.
It looks like it just directly plugs into the starter. The NSS is not active since it will try to start in any gear, which is why I think the NSS is in that 3 prong switch on the trans.
 
It looks like it just directly plugs into the starter. The NSS is not active since it will try to start in any gear, which is why I think the NSS is in that 3 prong switch on the trans.
So that L plug will go under this prong on the starter relay?

IMG_3218.jpeg
 
My bad, I steered you a little wrong.
The harness that you circled goes to the bulkhead connector.20231105_112456.jpg20231105_112453.jpg20231105_112438.jpg
On my car the wires plug directly to the upper bulkhead. It looks like yours has a connector from the BH to your nss harness.
Someone with a post 70 car can chime in.
 
So that L plug will go under this prong on the starter relay?

View attachment 1552097
I've been out all day so I'm just getting caught up. No, the L terminal replaces the brown wire on the bottom right of the relay; in your pic its making a 90° turn. The heavier brown wire to the starter solenoid is the only wire that is screwed down to the center terminal.
 
I've been out all day so I'm just getting caught up. No, the L terminal replaces the brown wire on the bottom right of the relay; in your pic its making a 90° turn. The heavier brown wire to the starter solenoid is the only wire that is screwed down to the center terminal.
I purchased the harness, and the NSS and reverse lights all worked. I appreciate everyone's response on here!
 
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