Alternator wiring question/advice?

Discussion in 'Workshop Forum' started by CnC79X19, Oct 30, 2019.

  1. CnC79X19

    CnC79X19 True Classic

    I'll try to make this simple, because "simple" is the extent of my electrical abilities on automobiles. Have a new rebuilt alternator and want to install it in place of the original. Old alternator, 3 wires. 2 in a plug with one of the 2 coming out with an eyelet style connector and a third single wire with an eyelet connector (battery I assume because it has power?). So the two with eyelets connect to the battery post on the alternator.
    New alternator- a few different threaded posts but no place to put the plug? Where do those 3 wires connect on the new alternator? The posts are all labelled with B- , B plus, I think there is a D and G there too? Don't have it in front of me to say exactly but want to wire it right.
    Any insight would help.
    Thanks in advance
  2. lookforjoe

    lookforjoe True Classic

    Pics would help

    Sounds like maybe your old one was external regulator, and new is internal?

    (Bosch) Internal regulator style only needs B+ (to/from starter), trigger wire (connects to idiot light, required to excite the charge - black/purple I think) and maybe a casing ground.
  3. CnC79X19

    CnC79X19 True Classic

    So the two wires that go to the battery post on B+ and the third trigger wire goes where Joe? There actually is a small light in the wiring harness that the original owner installed. Could that be the third wire? If so, where does it go on the back of the new alternator? Not sure if its internal or external, how can I tell?
  4. CnC79X19

    CnC79X19 True Classic

    I'll get some pictures this evening after work post them.
  5. CnC79X19

    CnC79X19 True Classic

    View attachment 26787
  6. CnC79X19

    CnC79X19 True Classic

  7. CnC79X19

    CnC79X19 True Classic

    Here are the back pics of the two alternators Joe
  8. lookforjoe

    lookforjoe True Classic

    My name is Hussein, "Joe" in my username refers to GIJoe action figures :D

    Not familiar with that Delco alt, I'd assume it's not factory though.


    All you need is the B+ heavy gauge, and then the black/violet wire to trigger the alt going to D+. Looks like your replacement needs a spade connector to plug the blk/vio into the recess where the D+ connection needs to go.

    If you can take a pic of the wiring that you have, we can figure out what was modified to fit the Delco/Remy alt.
  9. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    The new one looks like a internally regulated "Bosch" type alt. The GM (Delco) conversion has been popular over the years, and there are threads that outline the wiring changes needed to install one. That might help to compare what you have (wiring harness) to what you need, by reversing the process.
    Scroll through these 4 threads to see if anything helps; I did not look closely to see what is offered, but there should be something:
  10. myredracer

    myredracer True Classic

    EE here... I just spent a ton of time trying to figure out how to convert a 600 generator to an alternator and how to connect to a fuel pump relay and battery/alternator charge light indicator. I ended up buying 3 individual Sipea relays.

    The part marked AER 1505 is the integral regulator. B- should be the ground connection and B+ goes to the battery. I am guessing the integral/attached regulator disconnects the field coils when the ignition switch is turned off instead of a remote Sipea relay . The D+ I believe, should go to the battery charge light and fuel pump relay (if so equipped). I'd connect the B- to a ground and B+ to the battery and start the engine and check with a voltmeter before and after the engine is running. Not initially having the D+ connected shouldn't affect anything.

    If it goes up in smoke, I may have been wrong. :eek:
  11. Dr.Jeff

    Dr.Jeff True Classic

    Sin City
    Just a couple thoughts. Keep in mind that on the X the "battery" lead from the alt actually goes to the starter. Another cable then connects that post on the starter to the actual battery. So when "battery" is said, think "starter". And that lead (alt to starter) should really be a heavy cable just like all the other battery cables (it carries a lot of current). The stock one was way too small capacity.

    Also the "charge light" (on the dash) does need to be hooked up to the alt (the D+ terminal). The resistance of the dash charge light is needed to trigger the alt that a charge is needed. Otherwise it thinks nothing is connected and does not charge. It's often referred to as the "exciter" circuit.

    Those Bosch style internal regulators are fairly universal (not quite but close enough). So if anything does go wrong and the regulator somehow accidently gets fried, then you can try swapping in another one (pretty much any other one) in its place.

    The alt should already be grounded by way of the mounts (through the alt case). But like all circuits it is always best to have a dedicated ground to the engine block and the chassis.
  12. carl

    carl True Classic

    Can you trace the wires that came off the old alternator and see where they go?
    That would help a lot in giving advice, especially given that neither the old or new alternators appear to be the normal alternators for an X.
  13. CnC79X19

    CnC79X19 True Classic

    Just came back to the forum this morning and thanks so much to everyone for the help and advice. I actually took both alternators to the rebuilder and he advised me how to wire it and explained the system somewhat. You guys have simply confirmed everything he's said very much appreciated. Finally seeing the finish line here and may see it before the snow flies
    lookforjoe and Dr.Jeff like this.
  14. CnC79X19

    CnC79X19 True Classic

    Sorry Hussein, nice to meet you!

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice