I'm in the process of adding a subwoofer to my car. In doing so I spliced in a T harness to audio wires from the head unit and routed the wiring to where I Will be placing the Amp. I tested the speakers after that using the balance/fade settings from the head unit; all channels work as expected.
In the interest of future proofing my wiring I tapped all four speaker channels, that way if I decide to add a four channel amp I don't have to rerun another wire set. Unfortunately with four speaker wire sets, I didn't keep track of which is which, and need to verify which wire-pair belongs to which speaker channel.
I was wondering if I could use the balance/fade settings on my head unit and a multimeter to determine which speaker wire is which channel. I can set it up so only one speaker is active at a time and test the wire pairs with my multimeter, but I'm not sure if I should be looking at voltage, amperage, or both.
Best Answer
Switch to AC volts and crank up the music. Monitor the voltage at the splice.
Alternatively disconnect from the amplifier at the splice and attach a 1.5 V battery to each pair in turn. You should hear a little thump from the connected speaker as the DC kicks the coil slightly.