coil not sparking

We've just realized... again.. that the coil doesn't seem to be sparking. We have taken the coil wire off the distributor cap.. put it up and cranked the engine ... and couldn't see a spark coming from the wire. What causes the coil to spark? We have tested every wire, connection and fuse imaginable, replaced the computer, have power going to the coil, but yet cannot see a spark. Will it not spark if the timing is off?? Thanks for your advice!!

What year is this vehicle? You may have a bad ballist resistor that will prevent the electronic ignition from firing. It is usually located on the firewall or fender and is an easy part to replace. These often go bad and will prevent the coil from firing.

I just went through a simuliar problem with my 90 voyager. After changing out just about everything in the ignition system, I noticed my roter wasn't turning when cranking, Long story short... found the bottom portion of my timing belt was missing the teeth, by the crank shaft. Top of the belt looked fine. Good luck on your fix.