Looking for some help diagnosing an electrical issue that started today.

Car is a 1979 Corvette with:

• One-wire 100A alternator
• Progression Ignition HEI distributor
• Battery disconnect switch
• Electric cooling fans
• Electric brake booster

The car has been running perfectly for about a year with the one-wire alternator setup. The alternator only had the large charge wire connected from the alternator output stud to the starter/battery junction.

Today while changing spark plugs, I noticed an old red wire near the alternator. The original alternator setup had additional small wires, but they have not been connected since the one-wire alternator conversion. I tucked the wires away or at least I thought i did, started the car backed out of the drive way and noticed smoking from under the hood. After this I found that now the car will only start and all accessories will only work if both that wire and my main charging wire are connected to the alternator and when both wires are connected the car just doesn't shut off. So now my issue is when I have it setup like I have always have for the past year, just one wire from alternator to starter, nothing, ignition doesn't work BUT headlight work.
So all in all

Current symptoms:

With only the large alternator charge wire connected (the way the car has operated for the last year):

• Headlights work normally
• Large battery terminal at the starter has power
• No power at the BAT terminal on the distributor
• Turning the key to ON does nothing
• No ignition activity

With both wires connected to the alternator stud:

• All accessories power up immediately even with no key in the ignition
• Ignition works
• Engine starts and runs
• Key will not shut the engine off

From what I can tell this only started once the red wire was shorting and smoking against the alternator case. I tired to follow the red wire as well and it looks like it runs to the back of the fuse block in the firewall.

Any help or advice is greatly appreciated!

 

More than likely one of the fusible link wires at the starter has failed. Examine the first 4 inches of the wiring that attaches to the starter. You're looking for any signs of melting/burning.

 

Show us some pics of the wires.
I agree with the above fusible link failure. No biggie once you identify it if you can use solder and heat shrink.
I suspect the wires that you "tucked" away were hot and that you creating a fault (ground, short, etc). I'd go "untuck" them and make sure they're not touching anything before doing anything else.

 

Okay so I have an update.

Jacked up the car and looked at the starter, found a wire that was completely burnt in half in front of what I believe would be the fusible link. I crimped the wire back together, connected it to the starter and with no wires connected to the alternator the moment I turned the battery switch from off to on all the the radio and vacuum pump, but my electric fans didn't turn on and the wipers still required my key to be in the on position to work.

 

Your wipers never work with the key off. Highly recommend you go to Mad Electrical's Web site. Read there tech pages on alternators and charging systems. madelectrical.com.

 

Yes.... But what I'm saying is everything worked before without the key in the on position even the wipers

 

So I found a wire burned in half near the starter after the fusible link, I spliced it back together, reconnected it an all the accessories came on when the battery was on with no key in, but this time when I turned the battery off everything turned off rather than the Voltage jumping up to 17.

I did find this however which is definitely part of the problem



If I life the harness up all accessories come on, ignition still doesn't turn off the car but the key does turn it on, and when I move the harness down everything turns off I will post a link to a video showing what I mean.

 

Are those the connectors to the extension harness from the starter? The damaged wires are a long running issue, not something that just occurred. . If it is the extension harness, you can replace it for a reasonable price. The terminals and connector halves on the engine harness side are also replaceable. just my opinion.