tach wiring help

have a WICo tach with 3 wires and cannot figure it out 1 is the light where do the others go??? I am trying to hook it up to 289 motor there are two terminals on the the back of the tach one is marked "positive" the other one has no markings an the third goes to the light

 

one is a ground the other goes to coil.

 

tried the coil

 

well.then .i don't know what to say.

 

What's it out of, could it be that it came out of a positively grounded vehicle?

 

or the tach needs a sending,or the tach doesn't work at all

 

That was my next thought

 

which side of the coil did you connect it to? hopefully the (-) side that connects to the distributor...not the (+) side which connects to the ignition switch

 

Pull the cover off, term are probably marked. Most tachs require a hot and a coil side. More tachs get destroyed because people dont look at the back of them.

 

did that tach come off a tractor by chance?

 

here try this.

http://www.leverfamilysite.com/images/PDF_Files/Sun_Tach_ST-500_SST-700_Models_%20RC_SST_and%20Transmitter_EB.pdf

 

you need a transmitter.