Faztbullet or other knowledgeable folks

[Texasmark]

'02 Mercury 2 stroke 115 hp.

Tach in newly acquired old boat non working....same make / model as new tach.... just 20 years old and terminals rather than 4 pin connector. No deflection.

New Faria Tach: https://www.ebay.com/itm/Faria-Boat-...72.m2749.l2649

Checked voltages on 4 pin connector (connector PN specified by Faria) at rear of tach: (unplugged from unit and measured female pins)
Pin 1 12v DC power
......2 Lights 12v
......3 Ground (battery - checked to battery -, less than half an ohm and even ran a jumper back to battery, having 2 wires for ground.)
......4 Tach signal. 6.xx volts at about 1450 rpm...verified by separate digital tach.

Just like the OEM, needle doesn't budge. Can't do the "power on" test where the needle goes to max ccw because it's already there.

New regulator rectifier, with grey wire to tach. Old and new had battery voltage at 14.5v. Ohmed out ground of RR module back to battery, good low resistance reading. Shined up lugs and bolts between power and ground from battery good-n-tite and shiny.

Red 16 amp stator with 6 pickup coils. Set "Poles" to 12 (Position 5) as referenced on Faria data sheet.

Now where do I go?
Thanks

 

[Faztbullet]

Your missing the 12V to turn it on ...install a red wire to ING and blk to GRD and touch to a battery. the needle should go to zero, if not tach bad.

 

[Texasmark]

Your missing the 12V to turn it on ...install a red wire to ING and blk to GRD and touch to a battery. the needle should go to zero, if not tach bad.

The picture of the rear of it is in the ebay www. Nothing but the 4 pin connector. Pins 1 and 2 are voltage input pins. Pin 1 runs the unit and 12v is on the pin when the ignition switch is On or Start. Pin 2 is the backlight and is 12v when the boat light switch is on.

I did a test whereby the connector was inserted in the tach and measured the voltage at the crimp terminals where I installed the unit. Power was present then also.

More ideas? Thanks

 

[Texasmark]

Your missing the 12V to turn it on ...install a red wire to ING and blk to GRD and touch to a battery. the needle should go to zero, if not tach bad.

You nailed it sir.

The pigtail connector that fits the instrument connector had screwy color coding and that got me off on the wrong foot.....wired it up 180 out. When you said "zero when power is applied" I realized that everything was there at the connector, it just wasn't getting to the instrument. I dug out a picture of the pigtail I accidentally found on the www and sure enough, I had power going to the tach pin and tach signal going to the power pin. Swapping around and that was that. Had it out today and worked like a charm.

Thanks!