i bought a aftermarket wiring harness for my 2003 nissan xterra and a boss stereo and i know your suppose to connect all the wires with there matching wires on the harness and stereo, but i am confused on what to do with the ground wire, because both my wiring harness and the stereo have a solid black wire and both say ground (the wiring harness says chassis ground). do i connect those two wire, or do i ground them both separately to bare metal? i am confused and any help would be great
Connecting both separately to the chassis is in effect connecting them together to the chassis. The idea is that they both need to be held at battery negative.
Connect them together. Or, you can connect them both to metal, but that sounds like more hassle for exactly the same result. As long as your stereo ground is grounded (i.e. it eventually meets the body) it'll be fine, and the black wire in the harness will be hooked up to ground anyway so that is provided to be easy to connect to.
There's no standard method to ground a radio that I know of. Some radios are just grounded from the radio case to the metal in the dashboard (no actual ground wire). In my experience, using the factory ground location (through the stock harness) often leads to electrical noise in the audio system. What I try to do is get everything connected to a point that the radio will power up, but don't mount the radio. It's also helpful to leave the ground wire accessible so it can be moved to various ground locations to check for the one that eliminates noise the best. Start the engine and turn on the radio and check for noise. Then make a permanent ground connection and mount the radio. I've found that moving the Hu ground location from one bolt to another can have a drastic effect on noise. EDIT: The ground wire on the aftermarket harness is to receive the HU's ground lead. It probably goes off several feet to be grounded among a number of other (noisy) accessories. Personally, I probably wouldn't use that wire. Just cut off any bare wire and cap it. I'd use the wire directly from the HU, extend it enough to reach the firewall and do the trial and error to see what works best.
In a Nissan, you'll want to connect the black wire from the new head unit to bare metal. You don't have to do anything with the ground wire in the adapter harness (it probably lines up with an empty pin in the stock radio plug anyway).
