Electrical 77 CJ5 258 Prestolite no spark

[P@trick81]

No spark on plugs. Need help figuring out what voltages should be on original ignition system. Measuring 12vdc from red wire on coil + to battery ground with ignition on, 10vdc while cranking. If I pull the green- and red+ off the coil and measure across them I get 4vdc with ignition on and 5vdc cranking. All wires ohm out good back to ignition module. I have a good wiring diagram but no voltage values to reference.
Coil measures 2 ohms across primary and 10Kohms across secondary. Removed Prestolite distributor and the pick-up coil reads .5 ohms so I assume the pickup coil in the distributor is good. Could be ignition pack but I would like to test it before replacing.

I’m an electronic tech with good 12vdc knowledge.

 

[gert]

I would think your issue would either be the coil, pick up or the control module, Im not sure how to test the control module other than to swap it out tho, bit of a shoot with the piss poor chinese quality control these days, sounds like you've ruled out the pick up and coil

 

[Armyvet25]

Not sure if he's going to report back but, in my opinion the ECM and it's distributor need to be pitched in the trash, I'll bet money it's the big old ECM, I would only run points...that's right, points or an HEI which is the best, most reliable, easy to diagnose and get replacement parts.

 

[Posi]

No spark on plugs. Need help figuring out what voltages should be on original ignition system. Measuring 12vdc from red wire on coil + to battery ground with ignition on, 10vdc while cranking.

To answer your question,
You should have 6v with key in the on position (engine not running).
12v with the key in the crank position.
10v while cranking would normally start an engine.