No one home in the electrical shop.

Discussion in '1947-1954' started by cmkruse, Mar 24, 2022.

  1. cmkruse

    cmkruse Member

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    I would have posted in the electrical shop but there is no activity there. I have a question about hooking up the voltmeter in my 49/3100/1/2 ton panel truck on the back of the cluster are the 2 pins but they are not marked positive or negative can someone tell me which pin to connect the positive to should it be the one towards the charge side or the one towards the discharge side o f the gauge.
    thanks
     
  2. Bill Hanlon

    Bill Hanlon Member

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    First, that is an ammeter, not a voltmeter.

    The easy answer is to hook the battery to one side and the rest of the wires to the other side. Turn on the headlights. If the ammeter shows a discharge (towards the minus) you guessed right and you are done. If the ammeter shows a charge (towards the plus) you have it backwards. Swap all the wires and you are done. It won't hurt the ammeter to hook it up backwards.
     
  3. vwnate1

    vwnate1 Member

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    What Bill said ~
     
  4. cmkruse

    cmkruse Member

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    Is there a quick check I can do with the cluster removed (which it is) so I can hook it up right when I install it? Hey, it's only been 17 years since I took this apart and I just can't remember everything you know!!!!! P.S. thanks for answering an off forum post on electrical.
     
  5. cmkruse

    cmkruse Member

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    I need to buy some Prevagen!
     
  6. Bill Hanlon

    Bill Hanlon Member

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    There is if you have ...
    a working battery
    a load, like a heater fan motor or even a brake light lamp
    the ammeter
    some 16 gauge or bigger wire

    Hook it up like this.
    upload_2022-3-24_22-4-15.png


    When you make the last connection the light should come on. Look at the ammeter needle.

    If it is moving to the - (discharge) side the ammeter is connected correctly. Mark the X terminal as the one that you should connect to battery + when installed.

    If it is moving to the + (charge) side the ammeter is connected backwards. Mark the Y terminal as the one that you should connect to battery + when installed.
     
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  7. cmkruse

    cmkruse Member

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    Bill, THANKS. I have the stuff and will get it done tomorrow. I sure appreciate the help.
     
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  8. cmkruse

    cmkruse Member

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    OKay, now that you guys are the Electric Shop can you tell me the values of the five fuses in the 49 fuse box.
     
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  9. vwnate1

    vwnate1 Member

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    Do you want the factory ratings or how it's done to save your truck from catching fire ? .

    I'm no where near my books .

    Begin with 10 ampere fuses and if one blows, go up to a 15....

    Most lighting circuits take less than 10 amperes, in my stuff I use 8 ampere .

    The ignition isn't fused .
     
  10. cmkruse

    cmkruse Member

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    Well, I'd like to know the original values just for the sake of knowing but I'll go with the 8 amps. I have all new wiring with a 12 v generator and regulator. My only other item is the electric primer fuel pump you helped me with and I'm going to use a 5 amp there unless you have a better recommendation. Bill said 25% over the pump rating but I don't know the pump rating.
     
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  11. Bill Hanlon

    Bill Hanlon Member

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    My experience (and documentation) is with a 51 and later GMC, but I'm assuming the Chevies are the same. By then, the headlight switch had a circuit breaker, eliminating some of the fuses. The tail light and brake light fuses on these later models are both 20 amps, as I assume yours should be.
     
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  12. 52wasp

    52wasp Member

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    One additional thing to consider, a load at 12V vs 6V is half the amperage. So, perhaps the fuse values can be even lower.
     
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  13. Bill Hanlon

    Bill Hanlon Member

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    I agree, BUT ....


    Until Craig decides what lamps he is using he won't really know what his load will be.
     
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  14. vwnate1

    vwnate1 Member

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    5 amperes for the E-Pump should be fine .

    Head and taillights *might* possibly draw 15 amperes but you're supposed to have separate fuses for the left and right taillights and yet another for the headlights....

    Time was when GM and others fused to passenger side taillight to the dash lights so if the dash lights went out you knew you had no taillights......

    SAFETY KNOWS NO SEASON so if you have to err, err on the cautious side .
     
  15. cmkruse

    cmkruse Member

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    Lots of good information guys. thanks a bunch I want to try to run some LEDs so my Loads should be a lot less so I’ll do the trial and error thing.
     
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  16. 52wasp

    52wasp Member

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    you will likely need a flasher designed for LED (low current draw) bulbs.
     
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