Wiring at Starter - I am becoming stupider by the Minute

[scorpion1110]

Calling the forum Wiring Gurus. This has me stumped. I have wired a lot of cars but my mind isn't working on this one.

Here is the scenario and forgive me that this is not a Tri-five but I thought the wiring issue would probably impact an SBC with a non-original harness.

I have three wires at the starter in the stock harness.
8923

The top is large lug about 10 gauge. The middle is the solenoid wire and the bottom is about 6 gauge with a small lug.

So I know the yellow is to the solenoid, and the large lug is to the hot lug on the starter. I also checked continuity and have at the exciter and alternator lug:

8924

Its that heavy gauge small lug that is messing with me. I cant trace it under the hood. I have a thought that it goes in the firewall possible to ignition but cant see it. The wiring schematic doesn't seem to show it either. Its the bottom wire in this pic:
8925

ideas? It sure looks like factory ends. The starter is a mini-starter from Summit so perhaps I just terminate the wire because its not needed (which my gut is telling me) but Id like to know for certain.

As to colors/ both are grime colored and dark so my ancient eyes haven't noted the difference.

I have a feeling there is a Chevynut out there who knows the answer ;)

Any chance you guys can set me right?

S

[royk]

Looks like the wire that goes to the S terminal on the starter solenoid. Check to see if it has voltage when ignition switch is in the start position.

[TrifiveRichard]

I didn’t see what vehicle and year you are working on, but another possibility is this 3rd wire goes to the solenoid ‘Relay’ terminal that connects to the coil side of the original dropping resistor...

[scorpion1110]

Roy-

Here is the hook up for the starter.

8926

The large lug is no issue- obvious. The yellow with the other end up around the coil, I thought went to the solenoid with the spade connector and the coil. If the wire is ignition start, is it combined with the large lug wire at the hot lug?

The dizzy is an accell with a pertronix.

GM went to HEI in 1974 so the factory wiring is designed originally for a points ignition with a resistor.

Thx, S

[scorpion1110]

Its a 73 Chevelle Laguna. I think the third wire ran from the ignition switch to the solenoid to give it full 12V to start The large wire ran to the hot lug and the yellow wire went to the solenoid other post.

With the Pertronix, I think the red/black from the dizzy go to the +/- on the coil. The yellow to the + on the coil, other end to the starter solenoid spade connector. The big lug from the alternator and the positive battery cable to the large lug and kill the extra wire because it doesn't do anything now.

I THINK thats the answer but am not 100% sure.

S

[scorpion1110]

I think it went to a lug which I would not use with an electronic ignition and the mini-starter. I think it should just be terminated.

8927

You think?

S

[Rick_L]

The thing that makes me question what you said about the two smaller wires is that the one that goes to the "S" terminal is usually 12 gauge or so, and if you need to connect to the "R" terminal on a stock starter, that wire is usually 16 gauge.

The heavier gauge wire that goes into the firewall is probably the one that goes to the "S" terminal. It should connect to the starter switch or the neutral safety switch. That wire is purple on most Chevy wiring harnesses. The other wire should run from the "R" terminal to the + side of the coil if you have point ignition or an electronic ignition that needs a ballast resistor - on a 57 only - the resistor bypass is in the switch on a 55-56. Most mini starters don't have an "R" terminal.

Find out if the bigger of the two small wires is hot only when the ignition switch is in "start". Then find out where the smaller one goes.

I don't know if the Pertronix needs a ballast resistor or not. If it doesn't, you don't need that extra wire.

[chevynut]

I think the third wire ran from the ignition switch to the solenoid to give it full 12V to start The large wire ran to the hot lug and the yellow wire went to the solenoid other post.

That's what I'd say too. If you use an ignition resistor the "extra" wire should go to the positive side of the coil. You can check it with a ohm-meter to be sure. Since you went to electronic ignition it's probably not needed as you guessed.

[NickP]

Maybe this will help. 8928

[Rick_L]

Well that pretty much nails it as the colors on the car's wiring harness match the diagram.

[scorpion1110]

Thank you guys. I can see it now.

I was actually looking at NickP's diagram in the 73 Shop manual and just couldn't see it. However the dialogue on this thread cleared it up.

I also want to say, last year was a bad year, almost died, 7 surgeries, all that fun stuff. Still recovering or maybe just not as sharp - dont know. What I do know is that when I have needed help and made a post here, someone has always lent a hand.

And for that I say simply thanks I appreciate it.

S

[Rick_L]

Sometimes you just need a nudge that says you're going the right way or someone pointing out what you can't see. Has nothing to do with not being sharp.

Sounds like you're overcoming your health troubles if you're working on the car. Best to you.