Simple
An hour meter is nothing more than a digital count-up clock. It tells you how long your engine has been switched ON. Nothing more. Connect the positive terminal to the switched terminal of the engine switch. Use a meter to determine which terminal goes off with the key. The negative terminal connects to any convenient ground: usually, but not necessarily black. To test? hook it up to a battery and watch it. To make better use of your time you might make sure you have some varnish to watch drying at the same time.
