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76 Charger non-functional ammeter

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  • 76 Charger non-functional ammeter

    Hi: Although I have visited this forum a few times, I have now joined. I am hoping I can get some assistance with my car.

    I have a '76 Charger 360, 2bbl, non lean burn with the 100 Amp alternator charging system. I am the second owner of the car (for the past 11 years). The original owner (little old lady) just drove the car, no modifications etc. The car is very original with 52K miles on it and in very good/excellent condition.

    I can not seem to figure out why the ammeter does not work. I have all of the correct 1976 Dodge factory shop/electrical manuals for reference. I verified that all connections are good. If I connect a voltmeter (I believe that the ammeter is actually measuring milli-voltage drop across a shunt (the shunt develops a milli-volt drop as current passes through it) at the terminals where the ammeter is connected at the dash and turn on the lights, I see about 0.015VDC (15 milli-volts) at the terminals. However, the needle on the ammeter does not move. Using a separate test power supply and removing the ammeter from the car/dash, I started at 0VDC and slowly ramped up the voltage. When I got to about 0.2V (200 Milli-volts) I started to get movement of the needle on the ammeter gauge. After continuing to ramp up to about 0.5V (500milli-volts) I got the needle on the ammeter up to half way on the discharge side. I reversed the leads from the power supply to the ammeter and it showed about halfway on the charge side. It seems that the ammeter gauge is working?? If I understand correctly, the shunt is just a piece wire?? How can it be bad and not working correclty.

    Any help into this would be greatly appreciated. Thanks in advance
    Warren

  • #2
    Welcome.

    Long story on the amp meter. It's unusual if it does work. I've had times where I'd take the gauge out, clean the posts, and use a q-tip to clean the contacts behind, and it'll work. It's not wired directly into the system, which is a safer option, but has shown over time to less accurate. All the other Mopars that year had the alt. gauge wired "inline" or online withe a power wire. Ours is through a circuit board. I had to "modify" my dash once for speakers, using a hammer to widen the holes, and my gauge worked for about a month after that. I don't know if it builds up resistance or what, but it's one of those quirks I guess.

    Hope I explained it well enough.

    Oh, let's see some pictures (of the car that is......)
    .


    bringin' em back ~ to the Dodge Mahal !!....

    Where old Magnums can find a home.. :angel:

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    • #3
      Welcome!
      Shawn
      72 Demon 340 4 speed 3:91
      89 Dakota 408 727 4:10

      Comment


      • #4
        Welcome to Style, Rare76Charger! You came to the right place!

        I agree with Magnumguy.....I have owned 7-8 R-body police cars ('79-'81), and none of the ammeters ever worked. Since they all had the 100 amp alternator, I always knew it was charging, due to the distinctive "whine" of the alternator.....if you don't hear the whine, you have a problem, and it is usually the regulator, as those 100 amp alternators are almost bulletproof! The only problem I ever saw with them, when working at a Mopar dealership, was the occassional rear bearing failure, easily fixed!

        I never bothered to try and fix any of them, because charging was never a problem, even after 200,000+ miles.......

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        • #5
          Nice choice of car - my first car was a 1976 Dodge Charger SE. I bought it in 1981 with a non-functioning ammeter. Next car was a 1977 Cordoba, again non-functional ammeter. I put a junkyard tach cluster in the 1977 Cordoba and that ammeter worked. But I agree, most of them don't work.

          I had the same experience with the 100 amp alternators. They never failed to charge. I had one where the bearing got noisy but I had spares from junked cars so I never even bothered with the bearing fix.
          12 Dodge Challenger SXT, 99 Dodge Dakota R/T, 89 Dodge Dakota Sport, 88 Plymouth Gran Fury, 81 Dodge Mirada, 79 Chrysler Cordoba, 68 Plymouth Valiant My Garage

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          • #6
            Don't know about how the cars are set up but I had a late 70's 3/4 ton pickup with the 100 amp alt and the gauge on it didn't work either. Yes, it used a shunt on the back side of the gauge across the terminals. The shunt was nothing more than a strip of thin copper only this had 3 strips so I took one out and holy mother of horsepower, the gauge worked! And welcome to the site!!

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            • #7
              welcome charger
              Poorwhite boy

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              • #8
                76 Charger SE pictures

                I tried to attched a few pictures of my 76 Charger referenced in the discussion but I'm not sure how to do it. If you would like to see them please send instructions on how to post. Thanks

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                • #9
                  As far as I know, most cars with external shunts just used the harness itself as a shunt. I seem to recall an Imperial?? that had the ammeter wires spiced into the engine bay harness, and I either fixed a bad splice, or "moved" the splice to provide more length of harness (the large wiring) to make the meter more sensitive

                  I also did this on a couple of '70's Ford pickups by actually adding a short length of wire to the charging line wire. This may or may not be wise, on modern rigs with huge alternators.

                  You are not alone. I have had an 86 and 87 Ford Ranger, both had "numb" ammeters. My 98 Ranger has a voltmeter.

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                  • #10
                    Originally posted by Rare76Charger View Post
                    I tried to attched a few pictures of my 76 Charger referenced in the discussion but I'm not sure how to do it. If you would like to see them please send instructions on how to post. Thanks
                    http://www.moparstyle.com/forums/web...nto-posts.html

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                    • #11
                      I simply take out the meter, disassemble it, and replace it with a voltage meter. I relabel the face to volts, as well, but it isn't necessary.

                      Now I need to find a half round movement for the tach dash.

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                      • #12
                        Originally posted by wa3ra View Post
                        I relabel the face to volts, as well, but it isn't necessary.
                        Can we see pictures?
                        .


                        bringin' em back ~ to the Dodge Mahal !!....

                        Where old Magnums can find a home.. :angel:

                        Comment


                        • #13
                          Originally posted by Magnumguy View Post
                          Can we see pictures?
                          Wouldn't mind seeing that myself...2nd the search for the half/round.
                          WPC# 12304 / 1970 Plymouth Duster / 1972 Dodge Charger Rallye / 1977 Chrysler Cordoba

                          www.cordobaclubusa.com

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                          • #14
                            Welcome to Style Rare76 Charger. Yep, agree with everybody, those gauges hardly ever work and those big alternators never fail. We always add a volt meter, sometimes under the hood, just to see what going on now and then. And by the way we have a 75 Charger.
                            1975 Charger SE E68 323
                            1976 Cordoba 360-4 500 OD 355 Sure Grip
                            1977 Cordoba 400-4 727
                            1979 Magnum XE 360-4

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