In layman's terms (hey I'm a layman when it comes to this stuff too) the ECM/engine control module (AKA ECU /engine control unit) controls if & when the spark is generated. If it stops working then no spark occurs. <img src="/forums/images/graemlins/kewl.gif" alt="" />

Yeah but spark is being generated, it follows the coil wire to the dizzy, then I am just not sure how the ECM stopped it from getting from the center of the dizzy cap to the plugs? As he stated above... <img src="/forums/images/graemlins/confused.gif" alt="" />

Are you sure you have a spark coming from the coil going to the distributor? If so, then I don't think the ECU's your problem. I thought you meant no spark period. If the ECU doesn't drive the power transistor, then you won't get power going to the coil which results in no spark at the distributor.

So you have spark coming from the coil for sure? But no spark coming from the distributor? Have you checked both the distributor cap & rotor & the coil wire for spark? Someone else on here will know more about this as well.

Here's the wiring diagram for a 3.0 (89 but the 90/91's are very much the same as the 89).


As you can see, there's no further control from the ECU between the coil and the distributor. The ECU controls the Power Transistor which drives the coil which in turn provides the Distributor with power.

Maybe a bad rotor or cap - not making connection.

Frank

Well this isn't my problem... I was just reading above and the guy stated that it had spark to the dizzy and not any further... Then he got his ECM repaired and it works now... I was just wondering how that worked because he was getting spark to the dizzy, so he said...

I see what you mean now. Interesting. I wonder if he simply had 2 problems?

Ok ' If we go back to the basics, The coil develops its high voltage by energizing the primary winding. The period of time this is energized is called coil saturation or dwell. This builds a magnetic field that when the circuit is opened the field collapses to the secondary winding which in this case provides high voltage to the distributor cap. Excessive resistance in the primary circuit can reduce the secondary voltage produced by the coil considerably. So a bad transistor(coil trigger) in the ECM could in fact allow a weak spark at the coil wire, but will not be able to bridge the rotor gap.
Conner