Amp meter guage

[ABX131]

My truck came with one of those trio guage sets in it that mounts under the dash. It has the oil pressure, H2O temp, and amps. The amp guage is not hooked up and I have no instructions with it. Does anyone know what it wires to? Also I have an alternator which has the red wire to the back and a two wire plastic plug that plugs in to the top. The plug has been cut off and my wiring harness has only one wire running up to the alternator plug, what is the second tab used for in this plug?

[luvbowties]

Originally Posted by ABX131

My truck came with one of those trio guage sets in it that mounts under the dash. It has the oil pressure, H2O temp, and amps. The amp guage is not hooked up and I have no instructions with it. Does anyone know what it wires to? Also I have an alternator which has the red wire to the back and a two wire plastic plug that plugs in to the top. The plug has been cut off and my wiring harness has only one wire running up to the alternator plug, what is the second tab used for in this plug?

I'd swap in a volt meter in place of the ammeter. All the output current from the alternator should run THRU the ammeter; just a tad of amps run THRU a voltmeter.

Ammeter will be quite hot; voltmeter would be cool.

My theory: Since an alternator puts out even at idle, the ammeter would never read in its negative range, like a generator; so why have it? The voltmeter would show your alternator's voltage output( and thus its condition) which should be somewhere near 14 volts; if volts got down toward battery voltage(around 12), it would indicate condition of alter. to be inferior.

Hookup for voltmeter: one side to ground; other side to a "hot" wire. Wire size can be as small as 14 (maybe even 16) gauge--it just needs to "sense" a current-drawing load, small or big current doesn't matter--it just reads the voltage.

Hookup for ammeter: Loosen big red output wire from back of alternator(from output stud); splice same size wire to its end and run to + side of ammeter; run same size wire from - side of ammeter back to the alternator output stud. There will be places under hood, along wiring circuit, to lessen the length of wire(s) needed, but effect should be the same. Don't skimp on wire size for ammeter-install.

HTH,
Sam

[ABX131]

I just had this conversation yesterday with a friend...I agree I am better to find a volt meter that matches my set and swap it out. I was more focused on making what I had work and did not really ask if I really needed it or would be better served swapping it..

[luvbowties]

Originally Posted by ABX131

I just had this conversation yesterday with a friend...I agree I am better to find a volt meter that matches my set and swap it out. I was more focused on making what I had work and did not really ask if I really needed it or would be better served swapping it..

Sorry for the tangent. However, also supplied was the answer to what you asked about how to make what you have work--check the :"Hookup for ammeter"-section.
HTH,
Sam

[LostMy65]

Another vote to dump it for a voltmeter
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[61_FL_Apache]

I 4th that!