'70 starter wiring help - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

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post #1 of 9 (permalink) Old Mar 25th, 19, 9:15 AM Thread Starter
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Dave
 
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'70 starter wiring help

I'm hoping someone here can help me out. My '70 has an intermittent starting problem that is related to purple wire that goes to the solenoid getting less than 12 volts. I measured ~ 6volts one time. It's *not* the starter or solenoid. I ran a second wire from the solenoid up near the battery, to be able to manually activate the starter, and it works every time. (and i've already made the mistake of replacing the starter)

So the purple wire to starter solenoid goes back to the main electrical connector on the driver's side firewall. On the inside of the car, I think I even see where the purple begins, back at the neutral safety switch. But where does it get power from the key switch when in the start position?

According to this wiring diagram, http://www.wiring-wizard.com/Diagram...ompartment.gif It looks like a Pueple-w-Blue wire comes into one side of the neutral safety, and the plain Purple on the other. I can see some sort of striped wire on the one side, but where is that supposed to come from?

I have an automatic w/ column shift. The column shifter has been replaced by a B&M floor shifter.

Thanks,

-Dave

'70 Chevelle ZZ383/700r4/3.55, [email protected] -- Megasquirt2-Extra, Holley Stealthram / Hotchkis A-arms / Hotchkis Springs / B-body 12" brakes / 1.25" F-body swaybar
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post #2 of 9 (permalink) Old Mar 25th, 19, 11:24 AM
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Re: '70 starter wiring help

It has to be a poor connection somewhere causing the voltage drop.
Maybe at the neutral safety switch contacts or terminal connections or at the bulkhead connector, or even at the ignition itself.

Need to see exactly where there is 12 volts and where there is not 12 volts.
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post #3 of 9 (permalink) Old Mar 25th, 19, 11:33 AM
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Re: '70 starter wiring help

The ignition switch gets constant battery power. When switched to the start position, power is then sent down the heavy purple/white to the neutral safety switch. The contacts in the switch are closed in neutral and park.Your neutral switch should be in the floor shifter as the one on the column is no longer useful. I have seen people bypass the column unit by simply twisting the purple and purple/white wires together at the column switch and not using the floor shift switch at all. This is very dangerous, as the car can then be cranked in any transmission detent position. You need to find these wires from the column switch and route them over to the floor shifter switch.
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post #4 of 9 (permalink) Old Mar 25th, 19, 12:01 PM
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Re: '70 starter wiring help

Good point Mark, maybe the NSS wires have been poorly spliced to extend them to the floor shifter.

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post #5 of 9 (permalink) Old Mar 25th, 19, 12:45 PM
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Re: '70 starter wiring help

Quote:
Originally Posted by modern malibu View Post
The ignition switch gets constant battery power. When switched to the start position, power is then sent down the heavy purple/white to the neutral safety switch. The contacts in the switch are closed in neutral and park.Your neutral switch should be in the floor shifter as the one on the column is no longer useful. I have seen people bypass the column unit by simply twisting the purple and purple/white wires together at the column switch and not using the floor shift switch at all. This is very dangerous, as the car can then be cranked in any transmission detent position. You need to find these wires from the column switch and route them over to the floor shifter switch.
Funny you mention that...that's exactly what I did until I got my new shifter installed. Car stalled on me and I forgot to throw it back in park until I got it started back up. Almost rear ended someone in a parking lot because of it.

Yes, your most likely culprit is the NSS on the shifter is making bad contact or is wired incorrectly. Depending on the shifter you are using it could be wired differently for the NSS and the reverse lights, make sure you have the wires connected to the right terminals.

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post #6 of 9 (permalink) Old Mar 25th, 19, 1:18 PM
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Re: '70 starter wiring help

Here's a 70 color wiring diagram
https://www.chevelles.com/forums/mem...le-diagram.jpg



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post #7 of 9 (permalink) Old Mar 25th, 19, 3:22 PM
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Re: '70 starter wiring help

Dean,

I love that wiring diagram and I have it in laminated plastic for my 70 EC - on 11 x 17 tabloid sized paper. That diagram explained things in some of the hard to understand areas that my American Auto Wire diagrams did not cover very well.

Rick

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post #8 of 9 (permalink) Old Mar 25th, 19, 6:49 PM Thread Starter
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Dave
 
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Re: '70 starter wiring help

Thanks for posting that diagram Dean, that's helpful.

Neutral safety switch -- The neutral safety switch from my B&M Quicksilver is correctly wired. It's only 4 years old. I have spade terminals from the B&M NSS wires plugging into the factory NSS harness connector. I re-seated those connections, but didn't test the B&M NSS itself as it's relatively new. But it's pretty easy to bypass for testing and change if required.

I'm wondering if I have a degraded/failing ignition switch. It's almost 50 yrs old.

Of course, I went out to the garage to try and examine this further, and it worked every time.

-Dave

'70 Chevelle ZZ383/700r4/3.55, [email protected] -- Megasquirt2-Extra, Holley Stealthram / Hotchkis A-arms / Hotchkis Springs / B-body 12" brakes / 1.25" F-body swaybar
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post #9 of 9 (permalink) Old Mar 27th, 19, 7:58 PM
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Re: '70 starter wiring help

In the service-repair business, intermittent problems were always the biggest headache because when you start checking everything works fine.
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