Review on Enhance Your Car's Control: MicroBypass Parking Brake Override Bypass for Clarion by Joe Kokenge

Used on Clarion NX404 head unit. The blue wire connects to the booster activation wire (blue to blue), the black wire connects to ground (black to black), and the green wire connects to the parking brake wire on the main unit only. DO NOT connect it to the green wire of the car wiring and the green wire of the main unit, ONLY connect it to the green wire of the main unit. Don't bother with the radio chassis ground or relay, buy this, plug it in (it takes about 5 minutes) when you install a new head unit, it just works.