Johnson system check Tach working with Yamaha 90tlry

[200090tlry]

Does the 1999faria 7000rpm tach have right setting to even work? I see a 5 and 6 number that's it so I figure one is for johnson 2 stroke and other setting for 4strokes. If the 5 setting is a 12pole I should beable to get this working right. The red lights currently do there thing and beep at me but im pretty sure it's for looks as I doubt the installer would have taken the time to figure how to hook overheat,low oil and stuff. They work by grounding so there must be no volts when everthing is working good on Johnson. On back of tach I see purple 12volts,black ground,grey sending wire and on top the black and blue wires going to other gauges plus all other wires for sensors not hook up I think. What makes this units red lights work, I put volt meter on this but found no volts maybe the ground is disabled on johnson harness off tach. So Im thinking I need to see if that purple wire has power already, cut the grey wire before it splices and goes direct into the johnson tach. I found 8 pin harness under the dash I think is yamaha, red,black,yellow,green hanging in air unhooked comming off it. Yellow has been hooked up to some gauge on dash, so would hooking red constant 12volt to purple, grey to green, maybe black to black get tach working. Also how come the grey sending wire splices into 2 wires for gauges what else uses this signal besides tach. Alot of info but I appreciate your help. Just did some reading found system check johnson someone said the tach uses 12v,ground and signal from stator. Is the signal from stator different than yamaha regulator. Did more reading lol online the red has constant 12volts which is good, ground wire seems to work now green sending wire im not sure about. At this point I think going ahead and cutting those wires off tach grey,black,purple bullet connecting to red,black,green. Check for smoke lol will update if it works

[rodbolt17]

set the tach at 6, that is for 6 pulses, 12 pole.
dark green is tach send on the yamaha 10 pin main.
yellow is key on power, dont use the red or the tach wont turn off.
none of the lights will work, they will still self test at key on power but they wont work.

[200090tlry]

Tested purple wire and it's hot so this is supply power to tach

So everything is connected up already humm I will need to start the motor someday and see if grey wire has power. If it does then I suspect the tach maybe faulty, or regulator. Also I will check 8 pin I found green wire see if that has fluctuating power like signal from reg.

[rodbolt17]

faria is italian for junk.
cant tell you how many system check tachs were bad out of the box a few years back.
was a pain, do all the testing,install a new tach, start all over again.