amp gauge

[StingRay]

There are two hot wires. Both terminate under the hood, one on either side. You'll find one hooked up to the junction block next to the battery and the other on the drivers side at the junction in the main power feed from the fuse block where it tees off between the alternator and the battery. Both have little rubber fuse holders on them on the under hood ends. It is called a shunted ammeter and this is how it works. The amp gauge actually measures the voltage drop between the T junction and the terminal block by the battery. It uses Ohms law E=IR or I=E/R where I=amperage, E=voltage and R=resistance.The resistance of the wire is known, the voltage difference is measured by the gauge and via the formula I or amperage is what is displayed. Probably more than you wanted to know.