[catman48]

Can I attach the tach to my 04 9.9 4-stroke bigfoot? There are 3 wires from tach ,1 brown, 1 black ,and one purple, I have a OEM mercury service manual but don't see anything in there for it.

[Texasmark]

You need 12v, ground, and a tach signal. Additionally you may have an extra wire for separate back lighting for night use.

Black is usually a ground wire. The purple may be the tach signal.....mine is gray. The brown maybe 12v but voltage is usually red.

You can use a voltmeter to determine which is which . The tach signal should be a few volts when the egine is running.

Mark

[ricksrster]

Brown signal from rectifier.Purple 12+ from ign. Black ground. See your other post in Mercury section.