SS WHT SYS CHECK OMC

33850 Chesapeake Tachometer Gauge Gas with JE Outboard. Tachometers work by counting pulses generated by the ignition system, alternator, tach signal generator or magnetic pickup sender. The tach is hooked up to +12vDC, Ground. By selecting the right tach and setting the switch on the back to the correct position you let the tachometer know how many pulses are sent per each engine revolution. These tachometers have a warning light system built into the dial that show off warning indicators when a fault is detected from the engine.. Specifications Size: 4 in.; Color: White;.