Adam, OEM tach or aftermarket? You just need ignition power and a ground. If it has a backlight and you want it to dim with the other dash and HVAC lights you have to tap into the dimmer switch wiring for that. Otherwise, you can tap into your lighting to have the backlight come on with your other dashlights. It's easier to just tap the dimmer switch, you get what you want accomplished plus it'll dim with the other lights. Typically 5 wires total, if it has no backlight then only 3. I'll be doing a write-up on it soon after I help Damen get his figured out. Then I'll just have the write-up include aftermarket tachs as well. The actual redline might be 6900 but the ignition cuts out at like 6700. I hit the rev limiter in my XE once also hit it in my SE-R once, and man, that was not a nice feeling, it was like I hit a deer or something, scared the crap out of me.
