charging system wiring questions
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500, 472, 425, 368 Discussion, charging system wiring questions in Cadillac Engine Technical Discussion; I just drove my 72 deville to autozone and had them test my charging system: alternator output 63amps, voltage 14.75. ...
  1. #1
    billsif is offline Cadillac Owners Member
    Automobile(s): 1972 Sedan Deville
    Join Date
    Apr 2004
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    76

    charging system wiring questions

    I just drove my 72 deville to autozone and had them test my charging system:

    alternator output 63amps, voltage 14.75. diodes check out ok.

    I took off the voltage regulator earlier and drove it there and they tested it on their machine twice. both times all tests came out ok, so they said the voltage regulator was ok.

    a new one was only $11 but i was told it was recently replaced and it checked out ok. the alternator is less than a year old and it checked out ok too, and the battery is brand new.

    my problem is this, for those of you who dont know: when im driving my car i can hear a ticking sound coming from around the firewall in the middle of the car (right where the voltage regulator is mounted). it ticks about twice a second at a steady pace and every time it ticks all the lights in my car get dim. so i have a ticking noise that corresponds to the dimming of my lights. as i drive down the road i hear an annoying ticking sound and my headlights and interior lights and radio lights, everything... they all pulsate as they go from dim to bright every half second.

    my charging system doesnt appear to be failing at all... my car hasnt ever stalled and the generator light has never come on, and ive never had a dead battery. i just know the pulsating headlights annoy me and other drivers.

    i can only suspect the wiring of my charging system... i have the 72 cadillac shop manual and there's a little diagram showing the voltage regulator and alternator... it shows 4 wires coming off the voltage regulator, three (labeled F, 2 and 3) go to the alternator (to F, R, and BAT) and the 4th (labeled 4)goes to the ignition switch.

    the only interesting difference i see is a ground wire shown going from the alternator to the voltage regulator. it says (18 blk) and connects to GRD on the alternator and just a black dot on the voltage regulator. i assume 18 blk means 18 gauge wire and black in color, but i dont see this wire anywhere in my car. i also dont see how it would connect to the voltage regulator or the alternator, since the alternator doesnt appear to have a GRD post on it anywhere, and the voltage regulator doesnt either.. i suppose i could just attach an 18 guage black wire (i suppose color doesnt really matter to the metal regulator housing and connect the other end somewhere on the alternator??

    if you guys could help me figure out if i should have a ground wire from voltage regulator to alternator that would be great.. and how to wire one up if i can just do that. on the alternator all i see is the F and R which is one little clip with two wires in it, and then the BAT post that has a wire going to the battery and another going to the regulator.

    would this ground wire being absent somehow cause the voltage regulator to tick and the lights in my car to pulsate (voltage to be unsteady) ?

    thanks for reading this and for any responses.

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  3. #2
    jk1000 is offline Cadillac Owners Member
    Join Date
    May 2004
    Location
    tx
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    90

    Re: charging system wiring questions

    It is essential to have good ground connections between the alternator, regulator and battery. In some cases you would do well to add additional ground wires between these three points. You can use the mounting screws on the regulator for a ground connection. You can use the alternator mounting bolts as attachment points if necessary, but most alternators including the 1D have a terminal for grounding.

    You mentioned the "gen" light is not on. Does the light come on if the ignition is on with the engine NOT running? The light bulb needs to be functional for proper field winding excitation.

    Hope this helps, good luck.

  4. #3
    billsif is offline Cadillac Owners Member
    Automobile(s): 1972 Sedan Deville
    Join Date
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    Thread Starter

    Re: charging system wiring questions

    1D? is that my alternator? i dont see any connection in this book showing the ground connection on a non-integral regulator alternator/generator. in the steps for removing the generator it doesnt list any step for 'remove ground wire'. it says remove the two wires from the BAT terminal and then the double connector which both wires connect to the regulator.. it says nothing about removing or connecting a ground wire. both the '693 series' and '697 and 698 series' diagrams show only no 1 and no2 terminals, and BAT terminal. i would love to know how to hook up additional ground wires from the alternator and regulator, but should i in fact just connect these two grounds to each other? i know how to put a ground wire on the voltage regulator, and on the alternator you said i can use a mounting bolt if i cant find any other ground, but then where do the other ends of these wires go? there looks like theres a wire nut on the wheel well on the passenger side that used to ground something, but the wire is about a 1/4 of an inch long and just stops, and i dont see any wire that used to connect to it. :\ some more help would be really appreciated. thanks.

  5. #4
    jk1000 is offline Cadillac Owners Member
    Join Date
    May 2004
    Location
    tx
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    90

    Re: charging system wiring questions

    sorry for the confusion.
    The 1D is the alternator with external regulator and the 10-si has the internal regulator. These were used extensively in GM products of that era.
    The original stock wiring does not have a ground wire attached to the alternator, but time and elements can make existing grounds unreliable. The addition of ground wires (either as a diagnostic tool or as a modification) can solve numerous problems.
    Connect all ground wires together.

  6. #5
    billsif is offline Cadillac Owners Member
    Automobile(s): 1972 Sedan Deville
    Join Date
    Apr 2004
    Posts
    76
    Thread Starter

    Re: charging system wiring questions

    i just tested a mounting bolt for the regulator and a mounting bolt on the alternator and both of them showed 12.5V when connected to the battery + terminal with the car off. that makes me think that grounds on both the voltage regulator and alternator are fine? perhaps some other wire in the car (are there hundreds?) is grounded when it shouldnt be or shorted out or whatever.. i dont know how to isolate that though

  7. #6
    jk1000 is offline Cadillac Owners Member
    Join Date
    May 2004
    Location
    tx
    Posts
    90

    Re: charging system wiring questions

    Meter connected between battery + and bad ground usually shows full battery voltage. Only when a bad connection is loaded (pulling current) the voltage will drop. A volt meter pulls very low current (microamps).

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