67 Alternator NOT Charging Battery / What's this wire?

Discussion in 'Classic Mustang Specific Tech' started by mmi, Sep 12, 2009.

  1. I have a 67 with a NEW Alterternator, NEW Battery, New VR, and new Solinoid.

    The Alternator is not sending a chrge to the battery, which stays at about 12.5-12.7 volts.

    I disconnected the battery ground, and then hooked the DVM up between the ground cable and the ground post. It reads 11.4 volts ...does that mean there is a load somewhere that shouldn't be? :shrug:

    So, I started unhooking things one by one. With the red charge cable still connected, I unhooked a 2-wire ring on the positive post of the solinoid - it has a black and a yellow wire combo that both go into a multi-wire pigtail.

    The load disappears when that ring is off the positive post. Does anyone know where that wire combo goes? what it does?
    Lyle1977 likes this.
  2. Is one of the doors open? The courtasy lights will draw current.
    THe ring term you pulled off should be the feed to the fuse box.

    I suspect you are not getting 12v to the field winding or F term on the alt from the VR. I lost the connection to my F: drive, can't get to my pictures right now. See if any of this helps till I can get to my 67 wiring diagram:

    ford alternator wiring - Google Images
  3. Doors closed. No key in the ignition.

    The reason I asked about the black and yellow wire ring is because the volts drop to zero in the ground when I take it off, and somebody told me that's how you find the problem :shrug:

    How do you test to see if the VR is bad?
  4. Lets look at the diagram then for a 67...

    So, you have a current draw that stops when you pull the black w/yellow ring term wire from the solinoid-this should be wire 37B in the diagram. It does feed the fusebox. It also provides the path for the alt to charge the battery. Couple things to do first. Put the ring term back on the solinoid, pull the thick heavy wire off the alt & see if the draw stops (unlikely if alt is new), if not, pull all the fuses in the fuse box, and close the door, se if the draw stops-or pull one fuse at a time and check. I doubt this will produce anything either but need to eliminate it.

    WHatever you disconnect, leave disconnected till we find it.
    Next pull the plug on the VR and see if the draw stops.

    If you follow the wires through the diagram, you will see what we are doing.

    If pulling the plug on the VR stops the draw, hook everything else back up, put the fuses back, and make sure the draw is still gone.

    Couple other things, make sure the three prong connector at the alt harness s in good shape. CHeck wire 26 (ground)-you can see it should be grounded at the VR ousing (sheet metal screw) and at the alt, then at the eng block.

    See what that gets you and post back.

    Also, you can see wire 37B hits a tie point in the harness and goes to the alt and to wire 37A which goes to the ign sw ad turns into wire 21 (Yellow).

    You can also see that wire 35 should be the Field wire from the VR term "F" to the Field term on the alt.

    And lastly, you can see that wire 152 runs from the solinoid ring term back to the VR and should be the "A" term on the VR.

    THis will come into play once we find the draw and fix that, and then get it charging again.
  5. FYI---
    new or reman alternators have the ground Black plastic ring on the wrong part of the alternator.
  6. BarnStang,

    I'm back on the project/problem again...

    A couple of things:

    There appears to be two 'draws' at the solinoid - the black and yellow wire ring - AND - also a second small red wire ring (not the thick red battery term wire) ...they both go into the same wire harness/bundle, and either creates a draw when attached to the solinoid. The small red wire does not seem to be in the diagram, so I don't know what purpose it has been serving in the harness.

    I suspect that this problem is somehow leftover from a bad VR. I boiled my last battery (acid went everywhere, since cleaned up) and so I replaced the battery, the VR and the solenoid. (I didn't know how to test the VR, so I bought a new VR.) But now there is ths current draw from those wire rings connected to the solenoid - even with the Alternator and VR unplugged - and so with the engine running, no charge was going to the battery.

    I'm wondering if I need to start unwinding tape in the wiring harness and look for problems?

    So ...secondly, I just bought a new 60A Powermaster one-wire alternator that I plan to use after I get through this mess - not sure how to hook it up yet - thinking about using the stock harness plug (with the orange Field wire cut out) - hoping it helps - thinking it will charge the battery (without the external VR connected) even if there is a draw somewhere
  7. I've been messing with the car a bit more, and I'm not sure looking for a 'draw' is the issue. Even if there is a small draw somewhere, isn't my first issue to find out why I'm not getting 13.5+ to the battery with the engine running??

    To recap:

    My battery was not charging after putting in a new battery, new alternator and new VR.

    With the engine reved, I barely got any rise in volts at all (never above 12.8v with engine running - no lights on).

    I have pulleys, but I was told larger pulleys would not cause that that much of a problem (my crank/alternator pulley ratio is now about 2.2).

    Then the 'new' alternator went bad - tested it, and my new alternator failed.

    Thus, I bought another new, albeit *one-wire* 60A alternator, and I've been trying to check everything before I start the car with it, cuz I don't want to blow a second alternator (even if it ends up working fine as only a one-wire, it still haunts me to figure out what caused the problem.)

    So checking current again, the new VR seems ok - current is 12+ through the harness to the VR (wire 904) with ignition turned on, and it sends 12+ to the 'F' field winding back through the harness (wire 35) all the way to the alternator ...(again, I know the one-wire doesn't need that F signal now, but trying to find the bug that bit me before).

    Also, any suggestions where to buy a good red wire for the 'one-wire' from the alternator to the solenoid?

    Any ideas anybody? I'd like to fix this bug and get back on the road...
  8. Well, the 60A one-wire alternator seems to have done the trick. It kicks out about 14.5v at idle and manages the same with a load on and increases with RPMs, so I guess that's it. Not sure I trust the charging guage in the dash though. ...VR is now disconnected (although I dodn't know what the harm would be to have it still connected).
  9. I see this is a five year old post,, however the topic is very relevant. I just signed up for this site in hopes of getting some good advise.

    In short, the battery is not receiving a charge. It will hold a charge at 11.87 volts. It slowly decreases with the car running but does not loose a charge with the ignition switch off. I presume the alternator is bad - it is original. What else should I consider? A new battery? Voltage regulator? Wiring?
  10. pull a battery cable off while it is running .if it continues to run the alternater is good . you can have both the alternater and voltage regulater tested at Autozone and most parts stores ,usually free .
  11. Yep. Bad alternator. Ordered a new one and plan to replace the battery as I believe I damaged it. Thank you for the conclusive answer.
  12. Up grade ur alt to a 3g alt
  13. In 4 years I would hope it's fixed. :shrug:
    Hint: there is a date stamp in the lower left corner of the post :nice:
    And welcome to stangnet