Factory Tach Wiring

Found this after I posted the question. The longer stud going to positive switched makes sense as the connector pushes on to a bare stud and needs to be longer.

03-09-2010, 10:57 AM
The Spade terminal on the back of the tach goes to the negative side of the coil (signal) gray wire.

The longer stud goes to 12v switched power. (blue harness,goes to fuse block for acc.)

The case is ground.

My experience with the "Real Time Egineering" circuit board, is that all it does is make the pointer "move",so most people "think" they fixed it, I've checked probably 50 tachs using those, and "All" of them were inaccurate,
and if you have a bad Meter,it won't work at all!

I used to work at Redline Gauge Works www.redlinegaugeworks.com feel free to contact me regarding gauges/tachs/clocks.