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9/25/12 2:12pm - Original Message: 'What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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Little on the rough side right now, with new paint and new interior it will be looking fine!

Joined: 8/18/2012
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So i have now replaced the ignition switch, the starter twice, entire engine ignition system, and key tumbler.  I just got my new Neutral Safety Switch in, hooked it up and the car won't start... i can bypass the switch with a paperclip and the engine will fire right up, did i just get a bad NSS right out of the box or is there a bigger problem that i am missing?  The car has been doing this not starting from the key thing for a while now and i just don't know what else to do...

Thankful for all help!!!


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I hope to one day be as knowledgeable as most the guys on here... but till then I'll have to just keep asking the questions with the obvious answers....
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9/25/12 6:41pm - Reply: 'Re: What is wrong with this thing...'
F4Gary Gold Member
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Grapevine, TX - USA

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1972 LT-1 convertible with factory air.

Joined: 8/26/2006
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Do you really need a neutral safety switch?

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9/25/12 7:04pm - Reply: 'Re: What is wrong with this thing...'
rod7515 Lifetime Member
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Red Lion, PA - USA

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1974 White 350 Corvette, TH400 Automatic 1972 Tangerine /Go Mango Convertible 383 Stroker, 2004r Automatic

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Have you moved the shifter around at all while turning the key. The NSS will have some adjustment on it and you may have to loosen the screws that hold it down and move the switch a little. This is so it only will start in Neutral or Park. Yes you could have gotten a bad switch as well. The new one I put in mine only works in Park. The new headlight switch I got didnt function at all for vacuum. Yes Its very possible a new aftermarket switch could be bad! Arent these cars a blast! Best of Luck,
Rodney

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9/25/12 8:00pm - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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To Gary, yea i think i do need a NSS because i will eventually lose the paperclip i use to start the car and would be stranded! lol

To Rodney, i tried to move the shifter around while turning the key, then pulled the switch off and while it was plugged in moved it in very small increments by hand from one end to the other while turning the key and still got nothing.


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9/25/12 9:41pm - Reply: 'Re: What is wrong with this thing...'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Are you SURE you do not have this relay on your firewall?



The wiring diagram for the '75 shows it to be there, and most all '75s did have it. The purple "Start" wire from the starter goes thru this relay, turns into a Lt. Green w/black tracer wire, then to the firewall pass-thru, turns back into purple, and then goes to the NSS, turns into a purple w/white tracer going to the ignition switch.
If you have 12v on the purple/white wire with the key in the "Start" position, and it still will not crank, the problem has to be down wind of the NSS. If, however, you are jumping across the purple & purple/white wires to crank it, the problem is BEFORE the NSS, or the NSS itself..
If you have 12v at the purple/white wire with the key turned to "Start", but not on the solid purple wire, the NSS is bad. All of these checks would be with the NSS plugged in.







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Joel Adams
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9/26/12 11:13am - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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So i went looking for that relay, this is the only thing it could be that i found under the hood.



I tested all the wires going to and coming out of it and none of them were hot.  Could it be just a bad relay?


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9/26/12 9:17pm - Reply: 'Re: What is wrong with this thing...'
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Naw...that's the high speed blower relay.The problem with the wiring diagrams for the '75 is that they were originally drawn to include the seatbelt interlock system, since it was a government mandated safety item for ALL vehicles sold in the US in '74, and was intended to be continued. However....it was dropped sometime during '75 production. The early '75 cars had it, later '75s did not, but the wiring diagrams were not updated.
Even so, if you just take the relay out of the diagram, it would presumably just remove the lt green/blk wire out of the diagram/circuit, and that same wire would be purple all the way from the NSS to the starter solenoid.

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Joel Adams
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9/27/12 6:29pm - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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Little on the rough side right now, with new paint and new interior it will be looking fine!

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so assuming my NSS switch is good would the problem just be located somewhere along that purple wire?  and this whole problem is made EVEN more fun with my partial color blindness, and purple happens to be one of the colors i have trouble with! lol

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9/27/12 9:45pm - Reply: 'Re: What is wrong with this thing...'
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Well...also assuming you're getting a 12v signal from the ignition switch to the NSS. You say tho, if you jumper across the terminals AT the NSS, it will crank/start, right? If this is true, then the wiring from the NSS to the starter has to be good....and that also confirms that the signal from the ign switch is getting to the NSS, so....that pretty much leaves only the NSS as the problem.
I say this all the time, but "new" don't mean crap. I get new stuff all the time that ain't no good. How many new light bulbs have you ever put in that blew as soon as you hit the switch?

At this point, if I have read correctly what you have done, and that you can start the car by jumpering across the NSS, then I have to believe the NSS is the problem.


Another thought...do your reverse/back-up lights work? Do they come on when you put it in Reverse?

|UPDATED|9/27/2012 7:45:04 PM (AZT)|/UPDATED|


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Joel Adams
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9/28/12 8:22am - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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funny you should mention those backing lights... i have been looking for those wires that connect to the third part of the NSS for about 2 weeks now, granted it's been being preped for paint but i do visit often to do little odd jobs i have not been able to find whether that wire should come from the front dash or if it snakes in from the rear and behind the driver seat.  and i can't even find where the wires may have existed and possibly got cut at.  it is the driving force that has me considering replacing both my wiring harnesses.

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9/28/12 12:11pm - Reply: 'Re: What is wrong with this thing...'
Adams' Apple Lifetime Member
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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The back-up light wiring should go from the NSS forward, then across the dash to the drivers side, and to the back from there. ALL of the wiring for the rear part of the car runs down that side, afaik. The harness passes thru the rear bulkhead in the ds rear corner.

Don't know if this will help, and I'm going from memory here, but....



|UPDATED|9/28/2012 10:11:02 AM (AZT)|/UPDATED|


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Joel Adams
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9/28/12 12:36pm - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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oh geeze... if you labled that correctly i have been bypassing that switch by going from the starer to the backing lights... the 12V from ignition switch is the wiring plug that i can't find then... i assumed that whoever did whatever to this thing just took out the backing lights.

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9/28/12 10:06pm - Reply: 'Re: What is wrong with this thing...'
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Huh? Now I'm confused, but that's easy to do...LOL
If you do not have anything plugged into the connector I labeled as 12v from ign switch, then technically, there should be NO voltage at the NSS anywhere...the pink wires carry the voltage.
Something stinks in Denmark, and I'm smellin all the way over here....LOL

Lemmie git my Service Manual out, and verify all of the connectors on the NSS, but I do know for sure that the purple/white wire is FROM the ing switch, and the solid purple goes to the starter solenoid.
I also know that the light green wire is for the reverse lights....
Time for some research....but it's bedtime now. I'll be back in da mernin....


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Joel Adams
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9/28/12 11:26pm - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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Little on the rough side right now, with new paint and new interior it will be looking fine!

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Well Joel i'm definitely not on a time frame to get it fixed! lol i should have it out of the paint shop in the next week or so.  But i can tell you that before i put it in there that it DID start without anything plugged into what you labelled the 12V form ignition plug.  I know I pulled the NSS apart at one point and put it back together when this problem first came up and it worked for a while then it suddenly started up again without anything plugged in there, that is what had me thinking that it was the backing lights, i also havn't had backing or braking lights on this thing since i bought it! lol  what are the odds that someone did a really poor bypass somewhere in the system that i have yet to find that has burned out since i did crank on the ignition a little much while first bringing the engine back to life?

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9/29/12 9:52am - Reply: 'Re: What is wrong with this thing...'
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Well Jon...after much tracing of wiring diagrams, and getting cross-eyed, I have come to the conclusion that you may actually have the wrong NSS for the car. EVERYTHING I have shows the '75 with the seatbelt interlock system....all of the diagrams, and troubleshooting info show it. However, we know that the system was dropped during the '75 year model. The NSS you posted the pic of is for the seatbelt interlock system, which explains the extra plug you have no corresponding connection for.
My opinion now is, that you need to get a NSS for a '76. You should only have 4 wires on the switch. One power(12v) with key on, one for the reverse lights, and the two for the starter...that's it. If I look at diagrams for the '73, or the '76, that's what they have. Diagrams for the '74/5 show the switch with the lt green/black wire as part of the seatbelt interlock, going to the relay...that you do not have. This explains why it starts with you jumping across the connector with the  lt green/black wire.
As to how to explain how you were able to start it before, I can't.
There is probably a way to use the NSS you have, but you would need to use an ohm meter, and see what each pair of the wires do as you move the switch thru it's travel. You really only need to have a connection for the reverse lights, and starter. I think if you simply jump across the two purple wires in the vehicle harness, it will crank...but it will crank in any gear, so you need to be careful that it is in Park.



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Joel Adams
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10/2/12 6:33pm - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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Little on the rough side right now, with new paint and new interior it will be looking fine!

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okay, so today i finally made it down to the car and put the switch i have now on the car and tried to jump between the extra wires that are on it so that it would complete the circut and would allow me to start the car in any gear.  When i jumped the plug here the car will crank even with the key in only the acessory position.  will a 76 plug really fix all this?

I did call the manufacturer about this and they do think that the 76 NSS will fix this, so in a week or so we will know just how right you are! lol


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10/2/12 9:29pm - Reply: 'Re: What is wrong with this thing...'
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Duncanville, TX - USA

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#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas

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Yeeesh!This is really getting confusing now! You say that the plug with the two purple wires is HOT?? There should be NO voltage on either of those wires until the key is turned to "Start"....
That is weird...

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Joel Adams
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10/3/12 5:16pm - Reply: 'Re: What is wrong with this thing...'
Sarge81 Lifetime Member
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WEST SENECA, NY - USA

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Hmm, the "purple wire" deal. I remember that wire well. Ermm

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10/5/12 10:00pm - Reply: 'Re: What is wrong with this thing...'
73shark
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Overland Park, KS - USA

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1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.

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How hard would it be to check the NSS w/ a VOM?  That would either eliminate it as the problem or indict it.

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10/10/12 7:29am - Reply: 'Re: What is wrong with this thing...'
Mynewold75vette
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San Antonio, TX - USA

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Little on the rough side right now, with new paint and new interior it will be looking fine!

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Well i finaly have the car back from paint... guy stole my money and didn't paint it... Sarge, what troubles can you tell me of your purple wire issue.  I've been thinking about this and it seems like the purple wire is always hot if the key is turned.... any thoughts?

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