[eeeegs]

What do I need to know to swap out my gauges to a non-plug & play replacement? There's a two-in-one speedo/tach gauge I have my eye on that says it works with "most two wire sine wave and 3 wire hall effect" speed sensors and 0.5-6 pulse ignition signals for the tach . . . but I can't find any mention in the owners manual or elsewhere about the sensor types used on the GT 650 nor technical specs for its stock gauges.

[AzCal Retred]

Do you have a Fluke or other upscale high impedance VOM? You could start by monitoring AC & DC voltages on the circuits in question, that's harmless enough, maybe progressing to DC milliamps if the voltage readings don't seem to be telling the whole story. Signal modulation is normally done either by the field device varying circuit resistance proportional to some voltage drop signal the gage or PLC can interpret, or having the field device vary the milliamp signal of the circuit being monitored. Check each circuit one at a time, record results & wiring color codes. Take lots of pictures. Make a schematic of what you find. Then you'll have real, verified info to compare against the requirements of the new metering you hope to install. Post these here & you become the resident expert, albeit at the same rate of pay...