Any of you 292 owners replaced the tachs? Well I am but have a question on the wired connections

on my vessel
blue is switched light
black is ground
purple or purple black went to I terminal on old tach
grey or grey black went to S terminal on old tach.

Funny thing is on the starboard tach I have two wires connected to S terminal a solid grey and a grey black. What gives? Why two wires.

port only has one connection to S terminal.

any one care to comment?

Thanks,

LC

FYI second gray is for a speed switch on captains call.