FRYING WIRE PLEASE HELP

Discussion in 'Electrical Systems' started by NovahK, May 1, 2021.

  1. NovahK

    NovahK New Member

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    Hi, I’m hoping someone here can help me with a frying wire problem. I’ve highlighted the wires and ones associated in the pictures below to help make it easier to see on the diagrams. The car is 1973 Type LT w U14 gauges. Associated wires to the frying one are in ORANGE. The wire frying is highlighted GREEN, it is frying right out of the ignition switch only when the key is turned on. When I got the car the whole wire was burn from ign switch to fuse box so I replaced it w regular wire close to the original gauge. The original wire was a solid single core and it was replaced w a multi strand(not sure if that’s a problem or not, or if original wire has a certain resistance). I’ve tried replacing the alternator, new ignition switch, and I’ve traced back all wires and they go where they should. I’ve tried putting a resistor both out of the ignition switch and also where it connects to the alternator with no luck. I’ve read about the original amp gauges burning out but I have the whole cluster and amp gauge disconnected and the wire will still get very hot and melt with key on. I also found that the wire highlighted in YELLOW coming out of the firewall plug to the engine isn’t connected to anything and it says “Resistance Do Not Cut”. Does this need to be connected to something? I’m running HEI and i know it was originally to provide power to the stock coil while cranking. It goes back to the ignition switch so that makes me think it could potentially be a problem? Please help, this is the only thing stopping me from driving my car): if someone is local to the California Bay Area, I would be willing to pay to have someone come help me. upload_2021-5-1_14-16-57.jpeg upload_2021-5-1_14-20-25.jpeg upload_2021-5-1_14-18-15.jpeg
     
  2. Green hornet

    Green hornet Veteran Member

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    Because you now have HEI, the yellow wire that is loose in the engine compartment so no longer needed. It was used with the original points distributor. Make sure it’s not grounding somewhere in the engine compartment, that could be a possible issue.
     
  3. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    You could pull the Heater fuse, where the orange 12 wire terminates and see if that clears the problem. The 24 BRN/W wire will burn before the 12 orange. You could also pull the plug on the back of the alternator and turn the key to be sure there is no short in the alternator.
     
  4. NovahK

    NovahK New Member

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    I will try pulling the fuse. If I disconnect the alternator plug or take the terminal that goes to the horn relay off, the wire will stop shorting.
     
  5. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    My reply earlier was proof that I shouldn't post after just one cup of coffee in the morning. You are burning the field excitation lead. It goes battery, ignition switch, and back to the alternator. I think you have a short in the excitation system in the alternator. Take the alternator out, have it tested, and replace if necessary.
     
  6. NovahK

    NovahK New Member

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    I mean I’ll try it to rule that out but it did the same thing on my old alternator, though that was the problem so I bought a brand new one and it’s still doing it.
     
  7. 72SS9681

    72SS9681 New Member

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    Have you verified the wires going to the alternator are not switched? The wire from the ignition switch should be the exciter wire and be connected to terminal #1 on the alternator the #2 wire should go to the horn relay (per the wiring diagram) and the 10 gauge Bat wire should feed back to the battery. If the #1 and #2 wires were swapped I believe you would get a direct short when the switch were turned on. You said when the plug was pulled the wire stopped shorting. If that's not it verify the 10 gauge wire is good and connected to the battery. If it were not connected the alternator would be feeding it's entire voltage to the horn relay. Also where is the HEI getting its power? It should be switched power from the ignition switch. I would look for any non-original wires that the previous owner added and make sure there not causing your short. I'm by no means and expert at GM wiring but I've had my share of electrical problems and 99% of the problems were from previous owners modifying the original wiring.

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  8. NovahK

    NovahK New Member

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    Yes I’ve confirmed #1 exciter goes to ignition switch and #2 goes to horn relay. The HEI gets its switched power from one of the fuse box “IGN” ports. I’ve added a picture of how the alternator wiring is on my car, a little different from stock but still relatively the same, please lmk if you see something wrong.
     

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  9. 72SS9681

    72SS9681 New Member

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    My car is across town in storage so I can't confirm, but I think the Power from the bat terminal go's directly to the battery or starter lug. I don't think this is your problem but might give you a little better charging voltage to the battery. I guess if it were me I would disconnect all the wires involved and test the wires to see if your getting a short to ground or power is getting feed to the exciter wire from some other source. I keep thinking about what you said about when you disconnect the plug from the alternator or horn relay it stops shorting. If you disconnect the exciter wire from the ignition switch does it also stop the short? I have to go to my storage in a day or so and I'll take a look at my car and see what it looks like.
     
  10. rchydzik

    rchydzik Veteran Member Lifetime Gold Member

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    Your drawing looks correct to me. Is there a ground in the firewall plug? Or somewhere along the brown wire to the alternator? The red from the battery to the horn relay is the battery charge wire and should have a fusible link at the starter. There has to be a short to ground between the ignition switch and the alternator in the brown wire or the Brown/white wire. You said if disconnect the brown wire from the alternator, the short stops. I still think there is an issue in the alternator.

    Is this an ammeter? If so, doesn't the circuit loop from the bulkhead connector to the starter in parallel with the starter wire? If so, there should be two wires connected on the starter with the battery cable. I am not familiar with the details on the ammeter, hopefully someone else is.
     

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