Voltage Regulator Problem??

Discussion in 'Electrical and Ignition' started by coalman, Jun 9, 2018.

  1. coalman

    coalman Well-Known Member

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    Voltage surges up and down quite a bit, any ideas on this?? If I need a new regulator, recommend original vs electronic? Thanks a bunch....
     
  2. 67Dart273

    67Dart273 Well-Known Member

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    Try the following, make up a temporary wire. disconnect the VR IGN connection, and connect it direct to battery (or at starter relay "big stud) temporarily. See if this tames the surge.

    if not stab a meter probe onto the battery NEG post and the other into the mounting flange of the VR. You want very low, lower the better, zero volts is perfect. If not, the grounding needs improvement.

    Do that measurement with engine running fast to simulate "low to medium cruise" and first with all accessories off, and again with lights heater, whatever loads you can bring on powered on.

    If this does NOT seem to be the problem, have a look at the alternator brushes and slip rings. Worn, dirty/ greasy, gummed up, stuck, etc

    If that is not the case replace the VR
     
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    • coalman

      coalman Well-Known Member

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      Thanks...
       
    • coalman

      coalman Well-Known Member

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      Did your recommended step 1, the volt meter went to 16 volts, it did have an impact on the surge. Thanks
       
    • 67Dart273

      67Dart273 Well-Known Member

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      This may mean that you have poor grounding between battery and VR. What year? This the electronic 70/ later or mechanical 69/ earlier?

      If it's mechanical it may just be out of calibration, if you replace it you will likely get an electronic "look alike" replacement
       
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      • coalman

        coalman Well-Known Member

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        I have a very good ground for the regulator to the body, the regulator is an after market electronic, that looks like the original.
        Do you recommend the mechanical over the electronic? Thanks
         
      • 67Dart273

        67Dart273 Well-Known Member

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        What did the ground voltage test I outlined earlier show?

        You need the following:

        VR ground MUST be at same voltage as battery NEG

        VR power/ sense MUST be at same voltage as battery POS

        If these two are met and the voltage still charges high (over 14) then either you have a wiring problem causing the field to be bypassed, the VR is out of calibration, or the battery is bad

        Next, if you have a known good battery out of something else, might swap in long enough to see if it changes
         
      • coalman

        coalman Well-Known Member

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        I am confused are you talking about Voltage or OHM'S?
         
      • coalman

        coalman Well-Known Member

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        I am still working on this, new battery was a big help. Still have some voltage flux on the volt meter, next step is the MAD rewire. Thanks
         
      • 67Dart273

        67Dart273 Well-Known Member

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        I guess you mean the "14." 14 V is nominal correct battery voltage. VR is temperature compensated so they vary some, but with battery "up and normal" and with engine running at anything above low cruise, battery should run about 13.8--14.2V. Not below 13.5, and not above 14.5V
         
      • coalman

        coalman Well-Known Member

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        With new battery it is running 14 volts going down the road, the wife was behind me coming home from a cruise in and said she noticed the tail lights were brighter on the way back. Thanks
         
      • 67Dart273

        67Dart273 Well-Known Member

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        So it still pulsates, or no? It may have taken some time for the battery to normalize
         
      • coalman

        coalman Well-Known Member

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        It does pulsates, but it is a lot better.. Thanks
         
      • superchargeddrt

        superchargeddrt FABO Gold Member FABO Gold Member

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        Might want to install a relay from the starter relay battery post to the voltage regulator ignition terminal. I have found that dirty ignition switch contacts or bulkhead connection issues cause the ignition voltage at the regulator to fluctuate therfothe causing the battery charge voltage to fluctuate and ultimately causing the flickering/ pulsing light syndrome.
         
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        • superchargeddrt

          superchargeddrt FABO Gold Member FABO Gold Member

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        • coalman

          coalman Well-Known Member

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        • 67Dart273

          67Dart273 Well-Known Member

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          Actually I would not do it that way. I'd add a relay, OK, but cut the blue "run" wire coming out of the bulkhead. Use the wire from the bulkhead for the trigger, and use the relay to feed all the loads the key "did" feed. If there is a voltage drop problem, it affects everything under the hood fed by that line.

          Also a good idea to put a fuse link or breaker for the supply line.......something Ma did not do!!!
           
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          • superchargeddrt

            superchargeddrt FABO Gold Member FABO Gold Member

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          • coalman

            coalman Well-Known Member

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            Still messing with it.

            I swapped alternator at no charge, ran a ground wire from the engine block to the base of the regulator and it is bouncing worse than ever. What do you use for the relay you suggested ???
             
          • KitCarlson

            KitCarlson Well-Known Member

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            Messing, does not often fix. Use a voltmeter to discover what needs fixing. A voltmeter is used to measure the voltage at the blue wire IGN terminal to case ground of regulator, with engine running. If it measures about 13.8V, the regulator is good. Then measure IGN to battery (+), it is the voltage drop that likely varies due to poor connections at bulkhead, and ignition switch. Good is when the the drop varies only a few tenths of a volt. The other places to measure are regulator case, to engine, and regulator case to battery (-). They should have less that a tenth a volt drop with engine running, lights on.
             
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            • superchargeddrt

              superchargeddrt FABO Gold Member FABO Gold Member

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              Here is a link to a thread where I posted a diagram. If you have any questions just ask.

              Flickering or pulstating Headlights
               
            • coalman

              coalman Well-Known Member

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              Messing was a bad choice of words, I am trying everything I can think of to fix it!!! Thanks so much for your response!!
               
            • KitCarlson

              KitCarlson Well-Known Member

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              We all mess, me included. Finding the ills can be a bit ongoing with 50 year old cars. The voltmeter helps for a quick chase.

              With a schematic from the service manual, the bulkhead wiring and terminals can be identified. Terminals are available from waytek wire. The added relay helps stabilize regulation , but without fixing the drops, the load voltage may still fluctuate.
               
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              • coalman

                coalman Well-Known Member

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                I have the wiring diagram printed out with all the wires I can see in the charging system high lighted. My Multimeter has DC Voltage function and I have been using it. Thanks again...
                 
              • coalman

                coalman Well-Known Member

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                Did the blue wire to case both sides where the flat mounting plates are bolted to fire wall. I had to take the blue wire on back of alternator, as there was no room at connector on regulator, is that ok? Anyways .03 to .05 both sides. I ohm checked this wire before and it was good between alternator and regulator. Thanks