My understanding is that 3 wires are needed to connect a tach: ground, ignition, and send.<br />My Medallion gauge has a post marked "GND"(ground) and a post marked "S"(send) but no connection for the ignition wire. I have tried it without the ignition wire connected but it does not work. Could this gauge need a source for the send connection other than the rectifier?<br />Motor is a 1974 85hp Johnson, but the Medallion gauges seam to have been used on more Mercury applications.<br />Any help woud be appreciated<br />Thanks<br />Tim
