97 C1500 (4.3 L Vortec) refurbished motor wont produce spark

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I've looked at pretty much everything I can think of, it will crank but will not start. I have no spark at the ignition coil. I have swapped ignition coils and ignition control module, checked crank and cam position sensors, all grounds ohm out to ground, I have power and signal to all the connectors that need it. All the fuses are fine. Ecu should be fine because its just been sitting and hasnt moved for a couple years. I replaced it with the same motor. Still no spark. Can anyone think of anything I'm missing?
 

JeremyNH

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Get a scan tool that can read RPM. No spark to the coil may mean no ignition signal to the ICM from the PCM. If the PCM can't read crank position it won't send an ignition signal. This will show up as zero RPM during cranking on your scan tool since it is reading CKS RPM. One rudimentary way to check is to see if you get RPM indication on the dash when cranking. RPM on the dash counts pulse signal to the ICM. If it's flat the signal isn't making it out of the PCM which would mean that it's either wire or PCM (where you'll need a scan tool to tell you which it is). If you are seeing RPM on the dash during cranking then signal is being sent but either not received by the ICM or not being processed by the ICM.
 
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0xDEADBEEF

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Get a scan tool that can read RPM. No spark to the coil may mean no ignition signal to the ICM from the PCM. If the PCM can't read crank position it won't send an ignition signal. This will show up as zero RPM during cranking on your scan tool since it is reading CKS RPM. One rudimentary way to check is to see if you get RPM indication when cranking. RPM on the dash counts pulse signal to the ICM. If it's flat the signal isn't making it out of the PCM which would mean that it's either wire or PCM (where you'll need a scan tool to tell you which it is). If you are seeing RPM on the dash during cranking then signal is being sent but either not received by the ICM or not being processed by the ICM.

Different motors, but I chased a similar problem on an LS for a long time. RPMS were showing 0 via my OBDII gauge. It turned out the crank sensor wasn't all the way in the block even though the bolt had been fully tightened.
 

JeremyNH

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Different motors, but I chased a similar problem on an LS for a long time. RPMS were showing 0 via my OBDII gauge. It turned out the crank sensor wasn't all the way in the block even though the bolt had been fully tightened.
I wrecked my CKS sensor during my 24x conversion due to a wiring error when I was troubleshooting an issue with the tune that I had thought to be an issue with the sensor. It was easy enough to find since I was monitoring RPM though HP Tuners on initial start. But that's what I would have seen absent HP Tuners: crank, no attempt to fire, no rpm indication. There wouldn't have been either an ignition or a fuel pulse either because both are processed off of crank position. But CKS position would matter as well. If they used the shims that come with the timing cover on his refurb the senor probe may be too far away from the reluctor wheel to read. Or a bad sensor or sensor wiring (12V, gnd, signal). But a scan read of RPM during cranking will rule it in or out.
 

stutaeng

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Yeah, I was asking about injector pulsing because signal depends on the ICM/ crank sensor. It's worth checking to see/confirm those sensors are okay, or it could be possible you have a bad ECU.
 
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So I got a scanner and I did not read rpms, but it also came up with a P0336 code (CKP). How many volts should I be getting off each of the 3 leads? I tried looking it up and I saw anywhere from 9 to 12 volts off the hot, but I wanted to see if you guys new the correct amount, and off all three
 
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