ForesterES

Hey all, I am attempting my first install of a head unit this weekend and I was wondering: Is it ok to connect the adaptor harness ground to the ground on the stock wiring harness or should I ground straight to the chassis? I was just wondering the best way!!

Thanks in advance for any replies...

walight01

match up alll the colors on the wiring harness and just plug it in and it will work great

ForesterES

Yeah, that's what I was going to do...but I've heard it's better to ground the head unit directly to the chassis and not to use the harness ground. I was just wondering if that was a load of crap or not...

walight01

its not going to matter unless you had like a alpine HU that had teh v-drive in it. also, your intena will act as a ground as well

Dave Cameron

you actually have two things at play here, the ground plane for the radio and the car chassis, and the negative power grounding. Think of it like a three prong outlet, positive, negative and ground. In car audio we use one channel to do both the negative and the gound.
The antenna is a chassis ground function, not a negative power function. The negative of the internals of the radio doe not always have contact with the exterior metal case of the radio- the only way grounding the cabinet would improve the sound would be if you had a ground loop of some nature. Some manufacturers try to avoid any contract between the circuit boards and the exteror of the case to try to miminumize potential damage if someone accidently arcs a postive line to the case.
The negative out of the radio does directly connect to the circuit boards and will do what you need done, and the negative of line in the harness hooks to the chassis anyway to do it's job.
I have seen headunit chassis grounding done as part of the process of isolating and getting rid of injected noise, but normally the injection of noise is a function of the positive current coming to the unit, not of the ground plane of the car.
But- why not try both, and let us know what YOU think from doing the experiment? Heck I could see all of us running out and doing it should you report a improvment back!! and that would be kinda cool!

ForesterES

I am really looking for the easiest way to do this, so I'm gonna be lazy and use the ground on the Metra harness. If I get noise, I'll pop the unit out and reground it.

Thanks for the help!!