Mazda remote start problem

About 2 weeks ago I installed a Compustar 2w8000fm in my 2003 Mazda 6.  Everything was working great until a few days ago when I was on a long trip.  The engine suddenly stopped running about 2 hours into the trip.  I got the car to a shop and they replaced one of the ignition coils.  It happens to be the coil I was using for my tach sense.  The wiring diagrams from TechDirect said NOT to use the GREEN/ strip wire on the coil pack.  I had used the black wire.  I had the tach sense wire hooked directly to the coil wire, not isolated in any way.  Did I do something that caused my coil to fail?  I am concerned about hooking it back up and failing another coil.

Use the black under the dash, at the PCM....its a good signal

Where is the PCM?

Up high, on the drivers side dash, the wire is in the right connector! its hard to get too

I found a black box with 2 connectors going into the same side.  One connnector has 2 larger wires, a RED / yel and a grn/yel.  The other connector, the one on the right, has ~12 wires.  One of those is black.  Is that the PCM?  Do I probe that wire the same way I would at the injector?

I probed that wire and it was at .18V at idle.  The voltage would climb as I rev the engine.  But the alarm won't accept it as a tach signal.

The only way using a coil wire will cause the coil to fail is if the tach wire shorts to ground. Did you run the wire through a grommet? Double check and make sure the wire isn't shorting out somewhere.