no spark -96 S10 4.3L 200K miles

I am having an intermittant dieing/starting problem. Confirmed no spark. Confirmed good ignition moduile, confirmed good coil. No DTC's.

Questions:
Do I have to check out the camshaft sensor? everything I read says its not used for spark.

Do crankshaft sensors fail often? 4.3L X engine. Is the best way to get at it through the bottom?Hall sensor or VR sensor? I get mixed input on which one it has. IS there any thing in the distributor that can prevent spark?

Whats left? Crankshaft sensor, VCM, anything else? (I hope its not VCM)

My repair manual implies that error codes are set if the crankshaft sensor goes bad. Since I don't have error codes, can I use that as proof that the crankshaft sensor is good? (which than implies bad VCM?)

My next step is to put a scope on the crankshaft sensor and see if its outputing anything (locate wire at VCM, stick pin it, watch on scope)


My wife is out of town which gives me the opportunity to swap parts between her blazer and my S!0. So I have to wrap this up by Tuesday when she comes back. and the crankshaft sensor looks to be in a god awful place to get to

I'd check your Distributor Cap As well as the rotor.

I gpt it figured out (I think). Even though the coil was producing spark, it wasnt enough to get thru distributor and ignite the mixture. I could alternate between old coil and new coil and have the car run and not run.

Diagnoses: weak coil. Cost: $33 for new coil.

WHat gave it away were funny looking wave forms coming out of the ignition module.

I will be checking the distributor just to make sure because maybe the distributor degraded enough to so that a weak spark wouldnt work.