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Back Up lights/NSS wiring 73 FMX
#1
I have been working on trying to get the back up lights to work on the 73 convertible I bought a couple weeks ago. It has a 351C with an FMX transmission. There were no bulbs in the sockets, so I tried that first, but it did not work. I started checking and there is no power getting to the wire that goes into the socket. So I started chasing that down. Here is what I have so far. The signal lights, brake lights, courtesy lights, headlights and radio all work properly. The fuse is fine as well. 

The neutral safety switch is working properly as there is continuity between the 2 wires when Reverse is selected.

There is a small plug by the parking brake pedal. The part of the plug that goes to the trunk has continuity up to the socket. The part that comes from the engine bay, did not have continuity with the wire coming from the NSS.

I went to the engine compartment and found the plug that comes from the NSS and then goes into the car. There was continuity between the end of the plug that goes from the engine bay to the plug by parking brake. I followed the end of the plug with the wires coming from the NSS. Here is where the issue lies. There are 6 wires (I believe) coming from the NSS which are rolled up together with electrical tape, and out of that roll of electrical tape, only 4 wires come out, that go into the plug. The part where the wires are rolled up together is right between the block and the firewall so it is very hard to get to. I was able to get some of the electrical tape off and in the process 2 wires got disconnected. I found the wire for the BU light (black/purple) and connected it to one of the wires. Now I had continuity from the NSS all the way to the back of the car. So I just need to finalize that connection. 

I found a couple of wires that are spliced and not connected to anything else coming out of that roll of tape. One of these is the white/pink wire that should bring power to the "IN" part of the BU lights section of the NSS. The "OUT" part of the BU lights section of the NSS is the black/purple wire I mentioned earlier that now has continuity all the way back to the sockets.

I have looked at the wiring diagrams, but not found the answers there. My questions are:

1. Where should the white/pink wire be getting power from? Can I just get power directly from the alternator/battery positive terminal?
2. Since the plug still has one wire disconnected, what 4 wires should go into that plug? (1 of them being the black/purple wire) That way I can figure out which one I need to connect there.

Here is a pic to help explain what I mean. I have ignored all the other wires going to the plugs and NSS.
[Image: BULight.png]

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#2
(03-30-2017, 10:02 AM)Tataocb Wrote: I have been working on trying to get the back up lights to work on the 73 convertible I bought a couple weeks ago. It has a 351C with an FMX transmission. There were no bulbs in the sockets, so I tried that first, but it did not work. I started checking and there is no power getting to the wire that goes into the socket. So I started chasing that down. Here is what I have so far. The signal lights, brake lights, courtesy lights, headlights and radio all work properly. The fuse is fine as well. 

The neutral safety switch is working properly as there is continuity between the 2 wires when Reverse is selected.

There is a small plug by the parking brake pedal. The part of the plug that goes to the trunk has continuity up to the socket. The part that comes from the engine bay, did not have continuity with the wire coming from the NSS.

I went to the engine compartment and found the plug that comes from the NSS and then goes into the car. There was continuity between the end of the plug that goes from the engine bay to the plug by parking brake. I followed the end of the plug with the wires coming from the NSS. Here is where the issue lies. There are 6 wires (I believe) coming from the NSS which are rolled up together with electrical tape, and out of that roll of electrical tape, only 4 wires come out, that go into the plug. The part where the wires are rolled up together is right between the block and the firewall so it is very hard to get to. I was able to get some of the electrical tape off and in the process 2 wires got disconnected. I found the wire for the BU light (black/purple) and connected it to one of the wires. Now I had continuity from the NSS all the way to the back of the car. So I just need to finalize that connection. 

I found a couple of wires that are spliced and not connected to anything else coming out of that roll of tape. One of these is the white/pink wire that should bring power to the "IN" part of the BU lights section of the NSS. The "OUT" part of the BU lights section of the NSS is the black/purple wire I mentioned earlier that now has continuity all the way back to the sockets.

I have looked at the wiring diagrams, but not found the answers there. My questions are:

1. Where should the white/pink wire be getting power from? Can I just get power directly from the alternator/battery positive terminal?
2. Since the plug still has one wire disconnected, what 4 wires should go into that plug? (1 of them being the black/purple wire) That way I can figure out which one I need to connect there.

Here is a pic to help explain what I mean. I have ignored all the other wires going to the plugs and NSS.
[Image: BULight.png]

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White/pink wire is fused hot, and gets its power from the fusebox.  It goes to the four pin plug where the black/purple wire goes to the white four pin molded plug that connects to the tail-light.  I don't remember exactly , but I suspect the white/pink wire on the headlight harness side of the NSS/BU plug in the engine compartment should be a female bullet; the black/purple should be male.  I could have these reversed.  The other two wires on the plug should be red/blue.

Let me check your shorts!
http://midlifeharness.com

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#3
So if I understand you correctly, then the white/pink wire goes to the same plugs as the black/purple wire ( both the black plug in the engine compartment and the white plug near the parking brake pedal), but instead of making its way to the tail light assembly in the white plug, it goes to the fuse box? I would assume the fuse marked radio and back up light?

See the red lines in my drawing to show you what I mean.
[Image: BULight2.png]
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#4
(03-30-2017, 12:27 PM)Tataocb Wrote: So if I understand you correctly, then the white/pink wire goes to the same plugs as the black/purple wire ( both the black plug in the engine compartment and the white plug near the parking brake pedal), but instead of making its way to the tail light assembly in the white plug, it goes to the fuse box? I would assume the fuse marked radio and back up light?

See the red lines in my drawing to show you what I mean.
[Image: BULight2.png]

Let's try again.  White wire starts from fuse box and goes to engine bay plug.  From there, it goes to the NSS.  It then exits the NSS as a black/purple wire and runs to the engine bay plug.  It then exits the engine bay plug to the white plug, and then out to the bulb socket. 

The white plug is not a parking brake plug, but one of the two tail-light plugs.

Let me check your shorts!
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#5
Got it. Thanks for clearing that up. I just call it parking brake plug to reference its location.

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#6
I reconnected the two wires and they work now. It seems the high beam switch was removed. There is nothing on the floor by the accelerator pedal. I will focus on that later on though. Thanks for the help.
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#7
The high beam switch is on the floor by the kick panel, under the emergency brake pedal.



“If you can't explain it simply, you don't understand it well enough.”
--Albert Einstein
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