on my new clarion head unit i've got this yellow wire, says its memory back up lead. The instructions say to connect straight to battery. Should I do that or just put it to the wire harness like the old one?

then for ground, should I ground at the chassis by the unit, or should I put that into the harness too?

 

wire them both to the harness

 

Unless it's got a high powered amp built in (like some of the Alpines) you should be okay just connecting it to the existing wiring harness.

 

thanks guys