I'm looking for a Kenwood DDX712 bypass cod...

ok i got mine in and all you need to do is ground the wire i just ran it to the ground on the radio

you should be able to just ground the parking brake wire, but some HUs require a switchable or auto pulse signal. so you can either connect the wire and a ground to a two-way toggle switch and just switch it on and off, <--------for kenwoods or just buy this auto switcher that goes through the switching sequence automaticly once you power up your unit.<--------for Kenwoods. I know that for Pioneers if you want to use the togle switch, you Must switch OFF:ON-OFF-ON. to "trick" the unit. so a auto pulse is worth buying for the Pioneers.