Mercury - Quicksilver 821509T01 Power Trim Relay Mercury & Mariner Outboards 821509T01. Overview. If your outboard's trim system isn't responding or only works intermittently, the relay is usually to blame. The Quicksilver 821509T01 Power Trim Relay is the genuine OEM replacement designed for Mercury and Mariner outboards. It restores smooth, reliable power to your trim motor - so you can raise or lower your engine without hesitation.. Built to Mercury's factory standards, this relay handles the