No spark

[Joe Dirte]

1998 k1500. 350/4L80e. Was a full build project that i havent posted yet. Everything electrical is hooked up, have all grounds connected. Not getting spark. I was able to probe the white wire on ICM n hooked to battery it would fire. Did continuity tests in wiring and everything is good to go. Battery fully charged, couple gallons of gas, gettin 60 psi. So fuel isnt my issue. Anyone else ever ran into this? Oh and keeps throwin CKP code but thats new (4 different ones) and install was good. Im at a loss.

Also should my tach be readin when i crank it? Scanner isnt picking up any rpms when i hit the key.

Tried another pcm too n still same issues.

 

[east302]

What code number was that again?


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[Joe Dirte]

What code number was that again?


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I believe p0336? Chargin phone so cant pull it back up at moment.

 

[stutaeng]

Um, that seems like it's a crank position sensor code. How did you hook up the white wire to ICM to the battery?

I would check for pulsing at the ICM, if that's not pulsing, then check the crank position sensor. You can check it I believe for looking at AC voltage while spinning the engine over by hand. I tried it once by myself, and it's really challenging.

https://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/how-to-test-the-icm-1

 

[Joe Dirte]

Um, that seems like it's a crank position sensor code. How did you hook up the white wire to ICM to the battery?

I would check for pulsing at the ICM, if that's not pulsing, then check the crank position sensor. You can check it I believe for looking at AC voltage while spinning the engine over by hand. I tried it once by myself, and it's really challenging.

https://easyautodiagnostics.com/gm/4.3L-5.0L-5.7L/how-to-test-the-icm-1

I stuck test light probe down in the plug. Was actually an accident cuz i dropped it, it landed in it n coil sparked. It is crank code though. Same sensor that was in motor when i i bought it runnin.

 

[stutaeng]

I stuck test light probe down in the plug. Was actually an accident cuz i dropped it, it landed in it n coil sparked. It is crank code though. Same sensor that was in motor when i i bought it runnin.

Ok, so you have spark at the coil, but not on the spark plugs? None of them? Is the distributer the one that came with the engine? Is it spinning?

 

[Joe Dirte]

Ok, so you have spark at the coil, but not on the spark plugs? None of them? Is the distributer the one that came with the engine? Is it spinning?

Only get spark if the white wire is probed off battery. Otherwise nothin

 

[east302]

I believe p0336? Chargin phone so cant pull it back up at moment.

That code means the computer isn’t getting a signal from the CKP sensor. Here’s the diagnostic for it, I’d run through it and see what you find.

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[stutaeng]

Well, that's not a good thing. That white wire is not supposed to be feeding a constant 12VDC+ You may damage your ICM...I see @east302 has posted good troubleshooting information, please follow that...

 

[sntrym]

This might be a silly question, but is the crank position sensor reluctor wheel still on the crankshaft? Asssuming you had the motor out and rebuilt based on everything else. It would be under the timing cover