Tachometer Stopped Working

[donhisel56]

My tachometer stopped working after converting from breaker points to electronic ignition on my 73. I have another tach from a 74 which I tried with the same results. Any suggestions?

[vandor]

Is the wire that goes to the tachometer connected to the negative side of the coil?
What type of electronic iginition did you convert to?

[donhisel56]

I used the "Ignitor" by Pertronix with their high power coil. I'm not positive (no pun intended) about the negative ground coming from the coil. Pertronix instructions were to bypass the ceramic resistor on the firewall and combine all those leads together. There were several leads which I had no idea where their origin or destinations were. It runs greats just no tach. One blog I read said that the break points system and the electronic ignition both used the negative ground from the coil. I've only read of one other person who stated the same symptom. He had converted several different Spiders to electronic ignition, some tachs still worked but some didn't. Thanks, Don

[vandor]

Check the color of the wire going tothe tach on a wiring diagram. Ithink it's brown. Make sure it's connected to the coil.
I've been selling the Pertronix for SPiders for years and this is an unusual problem, so hopefully it's just a disconnected wire.

[donhisel56]

I'll give that a try. Thanks, Don

[donhisel56]

Thanks, you solved the mystery. I ran a test wire, as you suggested which caused the tach to work again. Upon finishing installing a new "brown" wire I found the old one lying "out of site" along the fender wall at the base of the coil. Thanks again!