1990 C.O.P 4th wire??

[niddydsm]

Ok so I recently changed over to a Coil On Plug setup. I figured the three wires out and am stuck the 4th. I know it is for the RPM (Tach) just not sure on how to hook it up.

 

[bonusboy]

http://www.dsmtuners.com/forums/bolt-tech/305921-how-make-proper-cop-setup.html

 

[Custom GSX]

I'm sure you need a tach adapter for that wire

 

[niddydsm]

That thread didnt pull up a diagram... Im assuming the Tach Adapter is just two diodes that hook up to the ground correct??