Electrical Question

Discussion in '1965 - 1973 Classic Mustangs -General/Talk-' started by 1966FordMustang, Jan 13, 2014.


  1. 1966FordMustang

    1966FordMustang New Member

    Joined:
    Nov 30, 2013
    Messages:
    8
    Likes Received:
    0
    Trophy Points:
    2
    1966 Mustang coupe has been running great. Replaced my battery and now problems...I traced a bad wire to a yellow wire running from my starter solenoid to this box (pictured below). The yellow wire is going into where it says "s" and is directly above another yellow wire that says if the wire is used for anything other than radio suppression it will cause electrical failure. Might there be a bad fuse in this box?
    I am getting 12.5 V to the starter solenoid but when I turn on the ignition I don't even get a click. Nothing at all. I checked the voltage on the opposite side of the solenoid and it is showing 0. So the current isn't making it through the solenoid thus no power to starter which is why I feel like there is nothing when I turn on ignition.
    Either way, the bad wire was tested. When it gets juice my ground all of a sudden has the 12.5 V. If I then connect my ground cable back to the battery I of course get lotsa sparks. There is no chafing on the wire between the solenoid and the box pictured. So I assume something has to be awry inside this box. Before I open it and look inside I wanted to see if I could get any input from you all. Especially, what the heck this box is!

    Attached Files:

  2. iskwezm

    iskwezm Advanced Member

    Joined:
    May 24, 2005
    Messages:
    4,159
    Likes Received:
    16
    Trophy Points:
    69
    the box is the voltage regulator, keeps the alternator from over charging the battery or allows the battery to take a charge from the alternator.
  3. 1966FordMustang

    1966FordMustang New Member

    Joined:
    Nov 30, 2013
    Messages:
    8
    Likes Received:
    0
    Trophy Points:
    2
    Okay. Thanks for letting me know. I went ahead and unplugged the wires from the voltage regulator and then tested the wire and no more short. So, I assume there is a short in the voltage regulator. Is my assumption valid? Thinking a new regulator, then plug it in, then whammo?!?
  4. 1966FordMustang

    1966FordMustang New Member

    Joined:
    Nov 30, 2013
    Messages:
    8
    Likes Received:
    0
    Trophy Points:
    2
    Replaced the voltage regulator and got a new starter solenoid. The short was in the voltage regulator and fixed, but I am still not able to start the car. On my solenoid starter I am getting juice to the terminals, except the last one that the starter cable is attached to. Any ideas?
  5. iskwezm

    iskwezm Advanced Member

    Joined:
    May 24, 2005
    Messages:
    4,159
    Likes Received:
    16
    Trophy Points:
    69
    Are the smaller wires on the solenoid reversed? Can you jump the battery terminal on the solenoid to the "I" small terminal and make it crank? Take the wire off the "I" terminal and using a test light or a meter, turn the key to crank and see if you have voltage.The wire from the ignition switch sends power to this terminal to avtivate the solenoid to send power to the starter.If you get no voltage on the smaller wire, there could be a break in it somewhere.
  6. 1966FordMustang

    1966FordMustang New Member

    Joined:
    Nov 30, 2013
    Messages:
    8
    Likes Received:
    0
    Trophy Points:
    2
    I can make the starter go by putting the hot wire to the opposite end of the solenoid. The small wires are not crossed up. Well, they might be, but I have moved them back and forth to test. I already tested the small terminals and they get hot when I turn on my ignition. So the big terminal with the hot wire is hot, the first small terminal is hot when I turn on ignition, and the second small terminal is hot when I turn the ignition to 'start'. But no matter what I do I cannot get the third terminal to get hot to send juice to the starter. I replaced the solenoid thinking that must be the problem, but that didn't work. I am stumped
  7. horse sence

    horse sence Please don't call me Mom SN Certified Technician

    Joined:
    Nov 30, 1999
    Messages:
    3,719
    Likes Received:
    573
    Trophy Points:
    153
    Does the starter solenoid click when you turn the key to start ?
  8. 1966FordMustang

    1966FordMustang New Member

    Joined:
    Nov 30, 2013
    Messages:
    8
    Likes Received:
    0
    Trophy Points:
    2
    Problem fixed. I had to ground the solenoid. Thanks for the help fellas.

Share This Page