[Chaindrive]

I have been searching through the forum for similar problems and have come to the conclusion that there are alot of Blazers sitting idle because of similar unsolved problems. If any of them ever were resolved, no follow-up posts were made.

I have gleaned a little info: The ecm will not cause a lack of spark? That could be good news and allow me to check test-able components only since there is no way to test an ecm except replacement I'm told. It seems everyone suggests the crank sensor, coil module, and/or coil as the places to look.

I have already replaced all of these (twice now; even going back to the old ones after the new ecm failed to do anything).

I am now trying to find a schematic showing all wiring for the ignition circuit and information on how to test for proper resistance/voltage values at each component with the key in both 'start' and 'run' and 'off' positions.

I am also considering tearing the dash and steering column apart to check for bad wires coming out of the fuse block and ignition switch. What a nightmare that might be... But recalling how it blew fuses to begin with (ecm #1 ; the original); did NOT blow fuses with ecm #2 (but progressed from occassional jolted "hiccup" to dead ignition over several weeks) makes me wonder if a melted wire behind the fuse block finally gave way. I have juice both in and out of both ignition fuses, but that doesn't mean it goes any further than that. I need to know where that juice is supposed to go from there (which ignition component and wire).

I'm desperate for a little advice here, guys.

It simply makes no sense. There are only a few components in the ignition circuit. SOMETHING is not working, yet everything except the entire wiring harness and ignition switch have been replaced.

Can I truly rule out the ecm (this one is new and is ecm #3)? It may be a faulty design and overly-complex method of delivering a simple spark, but it is STILL just a circuit and has to follow rules of logic.

Your thoughts would be greatly appreciated!