Depending on how you wire a two-battery 12-volt system, the result can be a 12 ... a mechanical marine dual-battery selector switch, and a battery isolator. This lets the alternator recharge ...

Stop walking across a dark room to turn on the light. Install a 3-way switch and control lights from two locations.

30 (other red wire) needs constant 12-volt power from the battery. 86 (gray/white wire) goes to the ignition switch. 85 (black wire) connects to the temperature-controlled sending unit.

The locking mechanism is engaged by an electromagnet via a 12-volt switch. It's a fairly simple install if you have a few key tools and some axle experience available to you. On our first test ...