Originally posted by ST1G
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So, I put in the new CPS, got it in there, got her all situated. No spark. put your meter on AC voltage and check across pin 47 &48 at ECU while cranking should have AC voltage being produced.see scope pattern below
Then I get to testing. I decide to put the multi meter on the coil positive (pin 15), and ground (body) and I'm getting 192Ω I get the same 192Ω when I put the meter between the negative terminal (pin 1) and ground (body) This was with the ignition on. This still doesn't make sense to me, since if the positive is grounded then the coil wouldn't get the signal to send spark. you cannot OHM test a live circuit (ie voltage present/flowing)
you can uses a test light to visually check between body ground and neg coil pin while cranking it should flash during cranking if ECU is controlling coil. understanding how a coil works will help diagnose ,for the coil to make spark current has to flow thru the coil primary windings for this to happen the voltage supplied thru the ignition switch has to go to ground this is done by the ECU the amount of time the current flows is called dwell ,with enough dwell time the coil primary is considered saturated and at the right time determined by the ECU using input from CKP sensor(correct spark timing)the ECU breaks the ground this causes the magnetic field around the iron core to collapse inducing a current in the coil secondary windings which have 100X more winding thus multiplying the voltage this voltage is sent out the coil wire and distributed by the cap to the right cylinders spark plug jumping the gap with about 10Kv thus ignition.if you put a test light on the coil neg you will see it flash as this voltage is present with no ECU grounding and drops away as ECU grounds coil thereby testing the entire circuit (voltage present ,yes ,light flashes yes ,ECU is doing something to control coil ) this cannot be tested with a DVOM as the sampling rate isnt fast enough (you need a scope instead)you might see the voltage drop down as the DVOM averages the slow samples but not a reliable test
After a few attempts to get the car to spark with nothing I checked the coil again and now I get a millisecond of continuity between pin 15 on the coil and ground and then it goes to infinite resistance (open). Same with the negative.
I then tried the coil from my running car. Same thing with the moment of continuity. No spark.
I don't even know any more.

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