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Discussion Starter #1
Hi. first time caller here. lol So, I have a 1987 S10 Blazer 2.8L 4x4 2 door. I need a list of what controls the spark. these all checked good: coil, pick-up coil, ignition module. But I am not getting a signal to the coil telling it to fire. I hooked up a second dist. and turned it by hand. Still no signal. Injectors are firing but no spark. No codes had battery in and out a hand full of times.:rant:
 

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It you're not getting signal look for a broken or burnt wire. Also, make sure your ECM is plugged in and working. I wish I was a little more help, sorry.
 

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The ignition module and coil are the only parts needed to produce spark. The ECM does not even need to be installed to have spark.

Where are you testing for spark? At the coil? At the coil wire? At the spark plug? If you are checking at the lug, check at the coil (wire), if you get spark at the coil wire, replace your cap, the button will likely be missing or extremely worn if that test pans out.

If you still have no spark, replace the coil, and/or check the signal between the ICM and the coil, the pink wire should have 12V on it, and the white will be a series of ground pulses (resting at 12V), that will charge the coil.
 

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Discussion Starter #4
i am testing at the lug. tester on top of the lug. used small piece of vacuum hose to hold tester on top of lug ><. no spark. so i then checked for voltage at pink wire and got battery voltage. replaced coil with no results. checked for the signal from the ICM using a test light probing white wire and alligator clamp on battery positive. did not blink. took ICM out and had it tested at autozone. tested in good condition. i also tested pick-up coil and it is also good. bad wire maybe? it was running great, then nothing. should I just get a new ICM to rule it out? I hate to throw money in to anything. there's always a test you can preform to figure something out. what pin does the white wire go to on the ICM? i'll do a continuity test on the wire to rule it out.


If you can't do it right, don't do it at all!
 

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when checking for pulse at the white wire you clip to a ground not on a positive - a pulse is created when the ICM or a set of points in a old school unit creates a open in a positive circuit feed and the the test light takes over for the open and lights the bulb in the test light
 
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