Wiring Amp Gauge... is this rocket science?

[75stepside]

Ok guys... i'm wiring up my guage cluster... and i'm double checking all circuits before i wire them for good... and for my amp guage (NOT vote guage), there are two terminals... i wired them one + and one - ... and the guage was either peged to "charge" or pegged to "discharge"...

to see if the guage was good, i put it directly on the battery and it melted my printed circuit a little bit and juiced the gauge...

i've got a spare... how do you hook it up!!! there's only two terminals, it shouldn't be rocket science!!

[Mike76251]

You hooked up that amp guage like you hook up a volt guage..........they are two different animals.
Going to the - and + post like you did will fry one quick.

Look at it like this................
You have a - wire and a + wire going to ........whatever
That amp guage goes on either the - or the + wire and measures the current going through that ONE lead.
I don't know what you want to measure but say, if it is the alternator output, the amp guage would attach to the wire coming off your alternator....going to the battery.

Just cut the wire and you have two wires right? One wire goes to one terminal on the guage and the other wire goes on the other terminal of the guage.
That also points out a problem with amp guages and why they are not used anymore.....if the guage fails= current stops in that wire.

[75stepside]

ah, that explains it!!! THANKS MAN...

know how the brake warning light circuit works... there is a signal wire from the brake porportioning valve and what is the other wire to light the light... positive or negative???

[NeCrOmAnCeR]

The wire which connects to the combination valve provides the ground for the lamp. When the ignition is on the lamp recieves 12 volts and if a problem occurs, the switch in the combination valve grounds the other side of the lamp.

As far as the Ampmeter hook up. The above discussion is correct,... However, on our trucks the ampmeter is a 'shunt' style. Meaning that the gauge measures the voltage across a shunt (actually a length of wire). As current increases/decreases or changes direction the resistance of the shunt causes a very small voltage to be produced. This is what the gauge reads. (After market gauges are connected as Mike 76251 said) Hope this helps.

[75stepside]

thanks man - that helps out a lot... the painless system is overall a great way to rewire your rig.... but, they do not cover every situation... i just want to make sure i have the circuits for my guages wired up correctly before i plug in and juice my printed circuit, or the $450 wiring harness... or the guages... or ....

thanks!