Neutral Safety Switch

[Nutinbutford]

Good day all. Getting underway with fixing all the "opportunities" I'm coming across with the newly acquired '73 vert, next up, no reverse lights. The car has a NSS with a quad plug AND a duplex plug which from I'm reading was used on a C6, this stang for sure has a C4 and according to the Marti Report was produced with that tranny. The switch is located on the drivers' side. I understand the duplex plug is for the seatbelt buzzer. All of the external switches I see on line for a C4 have only the quad plug. The part number I'm looking at purchasing is D2ZZ-7A247-C.

I'm not finding an external switch with both plugs specically for a C4. Is it possible that it changed after a certain production date?

Thank you for any insights.

 

[giantpune]

https://7173mustangs.com/threads/1973-neutral-safety-switch.31052/post-319056

 

[Hemikiller]

They're fairly common to find on eBay, but not "cheap"

https://www.ebay.com/itm/275386288800
IMO, you should diagnose your reverse light issue before throwing a $100 part at it. Pull the plug apart at the quad connector and with the key in the ON position, make sure you have voltage at the White w/purple stripe wire. That's the feed from the fuse box. If you don't have 12V, then most likely the #1 fuse is blown, but it also powers the windshield wipers and turn signals.



If you do have voltage, jumper the White w/purple stripe wire to the Black w/pink stripe wire. That will send voltage back to the reverse lamps. If they light up, then it's the NSS, whether it just needs to be adjusted, or the switch itself is dirty or bad. The NSS can be cleaned, I've seen a video somewhere, but can't find it at this moment.


If they don't light, probe the bulb socket with a test light, if you have power, then you have an issue with the sockets/bulbs or the taillight harness ground. If the sockets are corroded, then some WD and a brass bristle brush in a power drill will clean them up nicely. Work the spring loaded contact so it moves freely. If the contact face is damaged, you can add solder to build it back up.

 

[Nutinbutford]

Thanks so much Giantpune and Hemikiller, really really helpful. I had tried the simple stuff like bulbs and the fuse, had no idea on the jumper tests though. The reverse lights due illuminate with the jumpers, tomorrow I'll see if there's any adjustment/alignment in the NSS using the #43 drill.

Really appreciate the insight guys. Will let you know what I find.

 

[mrgmhale]

They're fairly common to find on eBay, but not "cheap"

https://www.ebay.com/itm/275386288800
IMO, you should diagnose your reverse light issue before throwing a $100 part at it. Pull the plug apart at the quad connector and with the key in the ON position, make sure you have voltage at the White w/purple stripe wire. That's the feed from the fuse box. If you don't have 12V, then most likely the #1 fuse is blown, but it also powers the windshield wipers and turn signals.

View attachment 80452

If you do have voltage, jumper the White w/purple stripe wire to the Black w/pink stripe wire. That will send voltage back to the reverse lamps. If they light up, then it's the NSS, whether it just needs to be adjusted, or the switch itself is dirty or bad. The NSS can be cleaned, I've seen a video somewhere, but can't find it at this moment.


If they don't light, probe the bulb socket with a test light, if you have power, then you have an issue with the sockets/bulbs or the taillight harness ground. If the sockets are corroded, then some WD and a brass bristle brush in a power drill will clean them up nicely. Work the spring loaded contact so it moves freely. If the contact face is damaged, you can add solder to build it back up.

Once again HemiKiller pulled the words from my mouth on a subject (a good thing). His suggestions re diagnosing the problem before throwing parts at it are reasonable. I am away from my laptop at the moment, but once back at it I have some detail 73 wiring schematics that may be helpful in the event you are still struggling with this.

Gil

 

[mrgmhale]

Okay, I am back at my laptop. Attached is a PDF file/schematic I think you will useful. For more PDF schematrics I had to place them on my Google Drive to share due to their size. Here is the link you can use to access them. One of the files is 1972 specific, nit for 1973. The file name will provide the description of the contents and the year it is relevant to:

https://drive.google.com/drive/folders/1Fnl-UBUh8h1N0Y_mVUXIWlUL_QJIfY1x?usp=drive_link

 

[Nutinbutford]

Thanks mrgmhale! These will be VERY helpful, sure appreciate you taking the time to make them available.

It was a learning day in the shop today, removed the NSS and cleaned it up. The switch is sealed so not much I could do internally. I sprayed electrical contact cleaner inside the switch as best I could, let it sit. Plugged the switch back in, no change.

While I wait for the switch I thought I'd rebuild the shift box, bushings are worn and the seal has deteriorated. Surprise! someone has broke off two screws that hole the console to the shift bezel. Appears they then proceeded to cut the wire to the indicator light inside the box. Yeah! The schematics will be helpful in finding out how this should be wired correctly.

 

[giantpune]

Appears they then proceeded to cut the wire to the indicator light inside the box. Yeah! The schematics will be helpful in finding out how this should be wired correctly.

There's a few connectors at the top of the firewall near the back left of the engine. 2 square ones that connect to the NSS and one single-wire white one that goes down towards the transmission tunnel. That round, white single pin wire is the one that went to the floor shifter on my auto car.

 

[Nutinbutford]

Thanks for your note giantpune. Yes, that's the same one I found on this car and confirmed in the wiring diagram. Connector ID in the drawing is C-606.

 

[Nutinbutford]

To follow up with the group, the NSS arrived today, problem solved, we now have reverse lights.

Thanks again to all for the input. On to the next character building opportunity.

 

[mrgmhale]

To follow up with the group, the NSS arrived today, problem solved, we now have reverse lights.

Thanks again to all for the input. On to the next character building opportunity.

Thank for the adxdvisory. I am glad the new NSS worked.