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1978 neutral safety switch replacement. If you are like me, you run into the same problem. You keep seeing videos that show you a neutral safety switch that is located on the steering column. That being said, it is very easy to replace this. Mine is a C6 automatic transmission. The switch is located on the driver side of the transmission. Remove one 1/2” nut and washer. Then slide off the arm or “bar”. Then remove the two 3/8” bolts or screws that hold the safety switch in place. Slide off the safety switch. This may take some elbow grease. Then you’re done. Replace with the new part and plug in your harness.
I wish there were more threads and videos for the 78 and 79. Unfortunately folks tend to include these two years in many videos and threads without knowing there are subtle differences between them and the 77 and prior. Please message me if you have questions. I’m no mechanic. Just an average guy with a shop and truck that is willing to learn.
Last edited by trevor.dinkel3; Nov 5, 2022 at 05:03 AM.
Man I am working on mine right now! Ugh. I replaced it easy enough. Starts as expected. Back up lights don’t work and I just can’t figure out the drill bit in the hole adjustment. It does seem there is a second hole anywhere below the first one.
Did you search on FTE? https://www.ford-trucks.com/forums/1...-f150-nss.html Did you make a new thread here on FTE and ask some basic questions? Or did you jump right on the U tube mechanic path? A set of paper back OEM shop manuals can help a ton. When the internet is down or your phone battery is dead.
Back up lights don’t work and I just can’t figure out the drill bit in the hole adjustment. It does seem there is a second hole anywhere below the first one.
Are you inserting the drill bit while the shifter is in neutral? If so, have you rocked it back and forth on it's adjustment slots at all (loose mounting screws)?
These days I would not put it past the manufacturer to have decided that, since they could not figure out what that hole in the inner piece was for, they just left it out! Or they just screwed up some and the hole is not cleaned out as part of the quality check process. Such as they are these days...
Frankly, even if you do eventually find the hole and line things up, it's actually quite common to get a bad NSS right out of the box these days. We hear about it all the time it seems. And if they do work out of the box, they fail within months of use.
Crap shoot...
Good luck. But don't drive yourself nuts. The hole might not actually be there.
Update. Success! Sort of. I took the switch off so I could shine a light in the hole and used some pliers to rotate the inside part until I could see the hole. At that point I inserted and small nail and taped it in place. I then installed the switch back on the transmission. I had to put the truck in drive so it all lined up. After I installed still no lights but the truck wouldn’t start in neutral. Pulled it back off and did it again. This time it started in park and neutral and the back up light flashed on for a second. I had my wife move the shifter back and forth and there was a spot where the lights worked but went out when it was fully in reverse. Loosened the 2 bolts and rotated left a bit more and they work in reverse now. Well one side does. Now I have back up on the driver but not on the pass. Switched bulbs. Same thing. In reverse I tested and get 12 volts in the socket. But still no light. Looks good inside but the bulb must not be making connection somewhere. Done for the day so I’ll mess with it later but it should be easy from here. Thanks all!!! Really excited to have back up lights.
Great news! Well, sorta... At least half way anyway.
The not fitting until you put it in Drive was a clue it was not going to work at that point. Supposed to line up the holes when in Neutral, so something was still off at that point.
Now that it's adjusted at least you know you need to look more to the rear socket that's not working because the wire is only one for both lights from the switch along the frame to near the back where it splits off somewhere.
You're saying that the side that is not lighting up now is getting 12v or is not?
When you switched the bulbs you saw that both bulbs still work, and it's not uncommon for the contacts in the sockets to get buggered up over the years. Loose, or bent, or broken. Or all three!
Good luck on tracking it down.
Oh, and how do the regular lights work? Are the running lights dim and the turn signals bright? Just wondering if that particular housing does not have a good ground.
Let us know what you find when you get the chance to come back to it.
Yes sir. After swapping bulbs the driver side still works and pass does not. Even though when it’s in reverse I can measure 12v on the pass side. Just must not be making good contact. They appeared very clean and in tact. I’ll try cleaning and adjusting and if that don’t work I’ll get a new socket and replace.
hadn’t noticed running lights being dim but I’ll look at that too. Sitting in a tree stand right now 😉. Appreciate the help!
Haha! Slow day in the tree stand if you're checking internet forums!
But I'd probably be doing the same thing, given the amount of time spent on our old trucks.
By "dim" I did not mean dimmer than normal. But that would be a clue too as a matter of fact.
What I was referring to was that perhaps the filaments were getting the wrong signal and your running lights were bright and your turn signal was dimmer. Opposite of normal.
That can mean a mis-wired new lamp housing (happens ALL THE TIME(!) with this aftermarket crap), or a missing ground connection causing one filament to try to use the other as it's ground.
Can cause all sorts of mischief.
I didn’t want to start a new thread as this covers most my problems. I am currently rebuilding a 1978 F250 when I received it somebody had just cut the wires on the neutral safety switch back up switch and had wired them to a toggle switch in the truck. I put a new switch on, and a Deutsch connector, and it starts in park in neutral, but I just can’t get the reverse lights to come on. I ohmed out all four wires and follow the one that goes back to the starter solenoid so I know what two wires are for that and those on just fine. The other two wires should be for reverse in that case and win not in reverse I am not making connection across those two wires, when I am in reverse I have tone on my meter I do not have voltage on any of it so I’m assuming this is a dry contact switch. Is there anything else that I could be missing? I have a diagram from classic carwiring.com and I do not see anything , but something Has to provide 12 V to my reverse any help would be grateful
Were you able to do the drill but adjustment truck on the switch itself? My right backup light needed a new socket. I had a break between the ground in the socket and the wire coming out to ground. I actually didn’t replace as you can’t hardly find them. I drilled the old one out and put a new ground wire and soldered it in.
I’m betting that’s it. I found it to be a pain. But the truck started right. Once I replaced the nss. It the lights didn’t work until I got that adjusted. Good luck!
Some talk about the NSS and the reverse lights. Having the NSS (actually Park and Neutral) functioning properly is VERY important. Safety 1st.
"When the trucks came with a manual trans, there was a dummy plug used to bypass the NSS switch. I've never been able to come up with a part number for the dummy plug. To bypass the automatic set up: Unplug the switch and discard or ignore. There are four wires in the harness plug, two each, red w/ blue trace and black w/ red trace. Run a jumper between the red/blue and red/blue, do the same for the black/red. That completely bypasses the NSS switch. Your truck will now start and the back-up lights will be permanently on. Now on to the backup lights.In the engine compartment is a little U shaped jumper wire. It'll be located on the drivers side splash pan, just in front of the firewall where the wiring harness comes through. Unplug the little jumper, this will shut off the back up lights. There should be a back up light switch on the trans cover. Run two wires from the switch to the two wires that were jumped. This will get your back up lights working again. Just a note, you could make a jumper plug out of the NSS. Cut the switch off the harness and splice the two pairs of wires. I just hate to cut these switches up. New, they're getting pricey. Here's the little jumper in the engine compartment. EDIT: If you don't care about the back up lights, just jumper the red w/ blue trace wires. This will by pass the NSS but the back up lights won't work."
Pretty sure manual trans NSS by pass and reverse lights plug.
Engine compartment jumper?
So are you saying that the wires were completely cut and toggle switches were used instead?
Or were only two wires out of the four cut and toggle switches inserted in between?
If all four wires were cut, then no amount of adjustment is going to correct a neutral safety switch that is no longer in the circuit.
They were cut at the switch and someone ran a toggle to the wires. I replaced the NSS BU switch. Ran the cable up to the engine bay and using a Deutsch connector put I back together. It work fine now for starting and doesn’t not allow it to start unless it’s in park or neutral. Now I’m just working on the backup/reverse light. Bulb plug is fine I can use my power probe to make that work. But when I shift to reverse I get no lights.
it’s a c6 automatic btw
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