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No one home in the electrical shop.

cmkruse

cmkruse

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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
 
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.
 
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.
 
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.
 
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 .
 
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.
 
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.
 
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 .
 
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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