1978 neutral safety switch replacement
Lead Driver
Joined: Jul 2017
Posts: 9,600
Likes: 1,174
From: San Jose, CA
OK. Sounds good. Sorry, I misunderstood the original post.
When you use the power probe, or a voltmeter, do you sense voltage coming from the ignition switch side of the harness when the key is in the ON position? It probably works in the ACC position as well, but in the on/run position for sure.
If you’re not getting 12 V on one of the backup lamp wires, then there is something missing somewhere else.
Maybe one of the fuses has blown? I think there is a fuse for the back up lamps. Especially if you have one of the later fuse panels with 10 fuses instead of the small one with five.
When you use the power probe, or a voltmeter, do you sense voltage coming from the ignition switch side of the harness when the key is in the ON position? It probably works in the ACC position as well, but in the on/run position for sure.
If you’re not getting 12 V on one of the backup lamp wires, then there is something missing somewhere else.
Maybe one of the fuses has blown? I think there is a fuse for the back up lamps. Especially if you have one of the later fuse panels with 10 fuses instead of the small one with five.
4th Gear
Joined: Mar 2023
Posts: 4
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Solved
Switch was aligned perfectly so I stsrted back tracking all the way to the fuse panel. Fuse was good but I had 12v on one side and nothing on the other. Turns out the block pins had corrosion. I cleaned it all up and they now work
Lead Driver
Joined: Jul 2017
Posts: 9,600
Likes: 1,174
From: San Jose, CA
Great!
good to hear it was something simple. And this comes up a lot with the old glass fuses.
If you didn’t already do that to all the other fuses, you might as well. This is something that every owner of an old vehicle should do every couple of years.
Remove the fuses, wipe them down and clean the contacts, put them back in.
Does usually keep some of these gremlins from popping up now and then.
good to hear it was something simple. And this comes up a lot with the old glass fuses.
If you didn’t already do that to all the other fuses, you might as well. This is something that every owner of an old vehicle should do every couple of years.
Remove the fuses, wipe them down and clean the contacts, put them back in.
Does usually keep some of these gremlins from popping up now and then.
Lead Driver
Joined: Jul 2017
Posts: 9,600
Likes: 1,174
From: San Jose, CA
With the glass fuses? No. But with the neutral-safety switch? Yes indeed.
Regarding the glass fuse corrosion, you would still want to do what I mentioned about cleaning them now and then, but the clue of having to jiggle the shift lever sounds more like the NSS coming out of adjustment.
Easy enough to find out though. I did not re-read the thread, but if we discussed how to adjust the NSS on the side of the transmission, perform that adjustment and let us know if anything changes.
Your '78 would have one on the side of the C6 where the shift lever is. Can't say for an F150, but on the 250 and 350 models, it's a royal pain to get to sometimes!
Yours a 2wd or 4wd?
Paul
Regarding the glass fuse corrosion, you would still want to do what I mentioned about cleaning them now and then, but the clue of having to jiggle the shift lever sounds more like the NSS coming out of adjustment.
Easy enough to find out though. I did not re-read the thread, but if we discussed how to adjust the NSS on the side of the transmission, perform that adjustment and let us know if anything changes.
Your '78 would have one on the side of the C6 where the shift lever is. Can't say for an F150, but on the 250 and 350 models, it's a royal pain to get to sometimes!
Yours a 2wd or 4wd?
Paul
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