i always thought most neutral safety switches just completed a ground circuit ?
at least that's how i have always wired them up on most [if not all] makes when i have used a universal harness or wired from scratch.

This sure makes it sound a lot like the solenoid on the starter is dying. Years ago, you could buy replacement solenoids pretty cheap and they were not hard to change. If that starter has been on the car for many years, and a replacement solenoid is still available, I believe I would just go ahead ans replace the solenoid on the starter.

The purple wire is definitely the hot one and is what's broke. When I first made the post I was sure it was the NSS since it worked whey bypassed and thought it was either bad but tested good somehow or out of adjustment. Once it happened again with the NSS bypassed, it turned into a whole different beast.

I believe your best approach would be to try the light bulb brightness test. If it is dimmer than normal when the problem occurs you will then know it is a current/connection issue.
All you need is a nail, needle anything you can push into the connector housing. Attach one end of the test light to the nail pin needle and the other to a clean solid ground. Any metal object nearby should suffice.
place the bulb where you can watch it when trying to start to car. If it's noticeably dimmer when the problem occurs you can back track from there or move it forward following the wire all the way to the starter if necessary. Could be an internally broken wire right at the starter. keep us posted.

Forget about the taillight thing and just use your test light to check for power on each side of the NSS when you turn the key to start. If you have power in and out then the switch is working correctly. I think you are making this harder than it needs to be. Circuit is simply ignition switch to nss to starter.

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The problem is that the typical test light can't put enough load on the system. You'll get false good readings that way. Hence, my home brew test light with a real bulb to pull some juice.

12.2 volts at the signal wire at the starter but no starter installed?

You should be reading full battery voltage under those conditions. You don't have enough to reliably activate the solenoid.

Since it sounds like the NSS and the bypass are getting power from the fuse block, your problem is between the fuse block and battery.

I didn't have much time to mess with it tonight. I did check voltage to the grounding points and all are the same as the battery. I got 0 resistance from the negative terminal to all ground points and ground points to other ones. I used the starter support bracket hole in the block, alternator bracket, starter mounting pad, fender, and negative terminal.

I will hook the light up next and install the starter and see what happens.

The original ignition is getting 12.36V, bypass is getting 12.08V, and battery is 12.56V. This is with the starter out. I know it's not the same as a load on it, but figure check it while it's out. At least I'll see if it's getting voltage.

If it's from the battery to the fuse block, how would I check that?

I hate working on things I don't understand, but do appreciate all the advice and like to understand how things work. I don't have time to work on it for hours at a time most nights.

I didn't have much time to mess with it tonight. I did check voltage to the grounding points and all are the same as the battery. I got 0 resistance from the negative terminal to all ground points and ground points to other ones. I used the starter support bracket hole in the block, alternator bracket, starter mounting pad, fender, and negative terminal.

____ resistance tests are ok but can be misleading. Hence voltage drop testing.


I will hook the light up next and install the starter and see what happens.

____ I'd leave the starter out for right now. If your previous voltage readings are accurate, we've identified a problem in the circuit controlling the solenoid. We don't need the starter installed right now and leaving it out allows access. Wrap some tape on the wires to prevent shorts since we'll need the battery connected.



The original ignition is getting 12.36V, bypass is getting 12.08V, and battery is 12.56V. This is with the starter out. I know it's not the same as a load on it, but figure check it while it's out. At least I'll see if it's getting voltage.

____ congratulations, you've just successfully completed a voltage drop test! Well close anyway. I'm assuming you had the meter probes connected to the solenoid signal and bypass one 1 side and battery negative on the other. Just run the same test with the meter connected to the wires and battery positive. From the readings above, you're losing .2 to .5 volts on an unloaded circuit, that's a huge problem. You really want a voltage reading of zero under these conditions.



If it's from the battery to the fuse block, how would I check that?

____ same as above but testing in different places. Battery positive to wherever. A wiring diagram is going to be needed and you're going to have to get comfortable upside down under the dashboard. No fun.


I hate working on things I don't understand, but do appreciate all the advice and like to understand how things work. I don't have time to work on it for hours at a time most nights.

____ to try to simplify, I'm sure you're understanding that electrical systems work on a complete circuit. The testing you've done on your own indicates that. Voltage drop testing lets you test different sections of the circuit, that's why you hook the meter up in different places.

Going to test the voltage at the IGN tab in the fuse block and at the NSS in and out tonight if I get a chance. Then try to find the purple wire at the bulkhead and check that. That one may be tricky as it's not real clean under the hood and all wires look black from years of gunk and doing it solo is a challenge.

Would a larger wire make a difference in voltage drop? I put a 12ga wire next to the bypass set up and it appears to be slightly smaller, guessing 10ga? I know the original ignition wire is supposed to be 12ga from what I can find.

I am tempted to run a wire with clips from the IGN wire to the starter solenoid, starter battery wire hooked up, and jumper cable from starter mounting point to a good ground and try to read voltage there. I would have to secure the starter from rolling around. Then do it again with the bypass wire. Is that a good idea? I really can't get a test clip or multimeter on the solenoid when it's installed. Too darn tight of a space.

Did a couple things when I got home.

Took the multimeter from the + terminal and to grounds. All showed same voltage as battery and did continuity and all showed OL.Not sure if that means anything.

____ not sure what you're trying to accomplish here.


Tested continuity from NSS (wires hooked up to NSS as they should be) to starter wire, IGN wire from under dash to console NSS (console had an additional harness added to move it to console from column), Fuse block to bypass button, button to starter, fuse box to starter and all showed 0. Had to depress the button to get the fuse box to starter to show 0 since the button breaks the circuit.

Voltage from IGN tab in fuse box is 12.03V.


____ too low, find out why. There's a problem between the battery and fuse block.

NSS in and out both showed 12.0V. Under dash NSS wire before it gets to the NSS harness for the console showed 12.03V.

____ too low, there's a problem between battery and nss

Starter wire showed 12.14V from ignition, which is more than the NSS reading. Not sure why?

Battery was 12.45V


____ battery is weak, needs recharged

I did hook a wire to the output of the NSS for the light socket test. I got it to light up in park and neutral was no light at the top end of neutral, but light at the lower end of neutral before it hits drive if that makes sense. It lit up all the time testing in park. I'll monitor that and see what happens. Hopefully the wire stays on it. I'll try to remember to make sure it's good before each start.

Not sure what steps I can take from here. I am going through all the notes given and will see what I can do, but called it a day for now.

At this point, if the bypass has less voltage and works all the time, I would lean towards the NSS towards the starter, but it wouldn't start a few times when it was bypassed so I'm still confused but willing to trouble shoot what I can. One thought I had was to cut the output of the NSS and run a new 12ga wire to the starter and bypass the bulkhead. Don't know if that would cause any issues.

____ you have a power loss between the fuse block and battery. The only practical bypass would be directly from battery to the solenoid.