My new-to-me boat came with both an airguide tach and speedometer. The tach is a 2 wire unit, with one being grounded, and the other going to the tach wire from my CD unit. It isn't working however, and I'm trying to deterime if it is the gauge, or the wiring is messed up. I pulled it out and verified it was adjusted to the 3 cylinder input position. Do these units get a 12volt signal from the CD box, whilt the other is grounded, or should it be connected to the alternator signal wire from the stator?
Thanks
Thanks