Starter solenoid problem

Discussion in 'Classic Mustang Specific Tech' started by stangman16, Sep 23, 2008.


  1. stangman16

    stangman16 Active Member

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    I think I have too much stuff connected to the starter solenoid + side where the battery connects to. I went to start the car, being it's been a month or so since I've started it after doing the EFI conversion. I go to hook up the battery cables and it sparks bad. Then after 2 seconds of having them connected I see smoke coming from the + side of the solenoid, it appears the wire sheilding was melting.

    I don't see what could cause this other than the fact there's probably too much stuff connected to the solenoid, but the engine has run fine this way several times before. So I need to remedy the situation, but I'm not sure how.

    On the + side of the soleniod, I have the + battery cable, EFI main wires, and starter cable, and maybe another wire or two that I need to figure out what they go to. (I'm guessing one is for the radio)

    In the pic below, the yellow wire fried and started smoking along with the solenoid burning out.

    [​IMG]

    By the way, this is a solenoid from the '91-93 mustangs. And I have a '91-'93 mini-style starter that I believe has a solenoid built onto it as well (if I remember correctly).

    Would adding a relay remedy the problem? Supposing that having too much stuff connected is what causes it to burn out..?


    Any suggestions?
  2. Tim65GT

    Tim65GT Active Member

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    Simply having a lot of connectors on one terminal is not going to cause wires to smoke. It's not a good idea, but there is something else. Track down what the yellow wire feeds.

    Something as simple as this could help clean things up:

    [​IMG]

    You could use a smaller Bosch type relay which can be mounted anywhere, since the mini starter already has the solenoid built in.

    [​IMG]
  3. stangman16

    stangman16 Active Member

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    Well, after searching the forum some more I ran into where it said to check the starter cable to ensure it didn't ground to the headers. Indeed it did, so I removed the cable from the headers, installed a new solenoid - no more sparks when I connect the battery. The yellow wire is one of the main feeds for the EFI harness.

    Problem now, is when I turn the key - nothing happens. No clicks, no starter engaging. I think hear the fuel pump priming.

    Could the grounding out on the headers have caused my starter to burn out? (I sure hope not, don't have $100 for a new one)
  4. Tim65GT

    Tim65GT Active Member

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    I don't think so. How is your solenoid and mini-starter wired?

    Here is a thread with discussion on wiring mini starters:

    I would check voltage at the battery, solenoid and make sure all the terminals are clean & tight. Then check the wire going to the solenoid "Start" terminal to see if it gets 12V from the Ign switch while turning the key.
  5. stangman16

    stangman16 Active Member

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    Thank you Tim65GT,

    I have mine wired the same as the first illustration diagram indicates. I appreciate the link, I was curious to know if it was correct - even though it's worked this way for quite some time now. I need to start saving these diagrams for future reference. I will have to get out there and check the voltage on Wednesday when I get the first chance to.
  6. stangman16

    stangman16 Active Member

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    I'm curious though, if the wire does not get 12v at the 'start' terminal from the ign switch while turning the key, would that indicate a faulty ignition switch?
  7. Tim65GT

    Tim65GT Active Member

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    That or the neutral safety switch bad or out of adjustment.

    I noticed in your pic you are holding the solenoid in your hand. If you replaced it and left it hanging like that, it would do nothing like you say. It has to be bolted to the car to complete the circuit to ground.
  8. stangman16

    stangman16 Active Member

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    Doh! You got me there, I did not bolt it back down after replacing it. I'll do that first, then check voltage if necessary.

    Where's the neutral safety switch located in a '66 Coupe?
  9. 65fastbackresto

    65fastbackresto Active Member

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    Dumb question probably but I`ll ask anyway.

    In your picture and in your desciption you show the battery cable and the wire going to the starter on the same side of the solinoid, shouldn`t they be across from each other to allow the solinoid to work?
  10. Tim65GT

    Tim65GT Active Member

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    Assuming you have a C4 auto it would be on the driverside of the transmission where the linkage is attached.

    But i doubt that is your issue. If you didn't have the solenoid grounded when you tried it, that is definetly the issue.

    He has a mini starter that has the solenoid built in. The external solenoid is being used as a tie point to pass the battery power directly to the starter (and other points). The 16-12 ga wire is all that is required to pass the "Start" signal through the contacts to the "S" terminal on the mini starter.
  11. chromedog

    chromedog New Member

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    maybe off topic, but GET RID OF THE WIRE NUTS!!!
  12. stangman16

    stangman16 Active Member

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    Tim65GT - Thanks! After rebolting the solenoid to the inner fender the engine cranks once again, and there is no spark when I connect the battery. :nice:



    I eventually plan to, I just hate to solder everything to have to re-do it later on. I say that because now I want to relocate the battery to the trunk..... Are there any good kits for this?
  13. Tim65GT

    Tim65GT Active Member

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    Here is a link with some battery in trunk info and pics.
    I like the heavy duty crimp trick with the flaring tool and punch.

    This is the Battery Box I used:

    [​IMG]

    I ordered my 1/0 gauge cable from these guys

    You’ll need a heavy gauge positive cable from front to back, ground cable from battery to chassis in the trunk and from engine to chassis in the front. You will need terminals sized to fit the gauge cable and grommets where you plan to pass through the firewall and other metal areas.

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