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2003 Silverado 6.0 NO spark or injector pulse, has cam and crank signals, no rpm

  • b4ctrooper
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30 Jun 2020 12:20 #40990 by b4ctrooper
Totally stumped on this. Here's the info and what I've done so far:

Bought a 2003 2500HD6.0 4WD rustbucket for the engine and trans. Sat for years not running. Cranks no start. No spark, no injector pulse (noid light flashes occasionally). Had a P0335 code. Found some broken harness wires going to the crank sensor so I ran new wires from the PCM to the sensor and new plug. Did the FSM troubleshooting for that code, crank sensor needs replacing. Crank sensor replaced TWICE! Still no start. NO cranking RPM on my hp tuners scanner.

Disabled the VATS with HP Tuners
2 new crank sensors
Bat+ at the injectors
Bat+ at the coils, and ground is good
Ran an extra ground from the engine harness to the battery negative (these trucks have ground issues)
Purchased an oscilloscope to test this thing. I have a wave form on both my crank and cam sensors (T pinned at the PCM), no rpm shown. I am a noob, so all I can say is there is a waveform. It looks consistent.
I have an extra unlocked pcm from a 5.3 Avalanche, swapped that in, no start

Any suggestions on what I should look at next? Having a crank and cam signal shouldn't I at least get an rpm reading?

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  • Tyler
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30 Jun 2020 12:22 #40991 by Tyler
Can you post the cam/crank waveform? So we can compare to a known good.

If you disconnect the crank sensor completely, will it start?

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30 Jun 2020 13:49 #40994 by b4ctrooper
I'll try to get something uploaded today. I did just get a P0336 now after cranking it on and off running some voltage checks on it. That's an out of range code so I'm still researching that.

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30 Jun 2020 17:17 #41001 by b4ctrooper
Went out and took some wave measurements. Here are some screenshots. I used a Hantek 1008C for this. This is only my second time using it so my experience is basically 0 and not too knowledgeable on what I'm looking at. If you see something let me know. Crank on the bottom, cam on the top

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30 Jun 2020 18:30 #41004 by Cheryl
Can you get mom and max Voltages on the cam and crank sensors?? I can’t tell if it’s pulling it all the way to ground.

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30 Jun 2020 18:48 #41005 by Matt T

Cheryl wrote: Can you get mom and max Voltages on the cam and crank sensors?? I can’t tell if it’s pulling it all the way to ground.


The channel markers on the left are 0 V with the hantek software. He's set at 5 V/div so the waveforms are topping out at around 10 V.

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30 Jun 2020 18:51 #41006 by Cheryl
Only other thing I can think of is pin figment at the pcm connector. Have good terminal drag??

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30 Jun 2020 19:14 #41007 by b4ctrooper
Any way to double check the pin to make sure it is connected well? I T pinned it to take these measurements. Also, does the crankshaft waveform look correct? In some areas it doesn't look consistent. Just throwing that out there as I am unsure of how to interpret that waveform.

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30 Jun 2020 21:32 #41015 by Tyler
Thank you for the waveforms! :cheer: I marked up a couple parts of your capture.



As you can probably guess, these shouldn't be here. :silly: The fact that it happens once every crankshaft revolution suggests a possible reluctor runout or metalurgy problem. Too regular to be a shorted wire, IMO. Happens too fast to be a shorted CMP.

The CMP waveform looks great, so there's still a good chance this thing will start if you disconnect the CKP. If it were me working on this truck, I'd either pull the CKP again and use a borescope to inspect the CKP reluctor, or pull the oil pan and inspect for damage.
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30 Jun 2020 21:51 #41019 by Cheryl
Wouldn’t he still get somewhat of a rpm on the scanner?? He said it stays at 0. Just a guess though.

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30 Jun 2020 23:35 #41026 by b4ctrooper
I will try unplugging the Crank sensor tomorrow and see if that does anything. If not I might have to pull the sensor and starter then to check the reluctor ring. Thanks for the input. If anyone comes up with any ideas please let me know. I really wanted to hear it run before I pulled the truck apart.

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30 Jun 2020 23:47 #41027 by b4ctrooper

Cheryl wrote: Wouldn’t he still get somewhat of a rpm on the scanner?? He said it stays at 0. Just a guess though.

I have been wondering that myself. After seeing Tylers last post, I think the sensor may have a dead spot in its' reading. Maybe that would not let it read each revolution? Pure speculation but it is the best reason I can come up with having all the info before me. I thought the waveform looked strange. Since it's consistent, the reluctor ring is very suspicious.

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01 Jul 2020 12:49 #41031 by b4ctrooper
Pulled the starter and sensor. Turned the crank 2 revolutions, and I observed nothing out of the ordinary. Only thing left for me is I'll wire wheel the block where the sensor mounts. It's a rustbucket so there may possibly be a buildup preventing the sensor from going in all the way. Worth a try

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02 Jul 2020 13:09 #41047 by b4ctrooper
WE HAVE SPARK AND PULSE!!!!! Here's what I did:
Went back to the truck today and watched the scope while turning the crank by hand looking at the cam sensor. I had a rough idea where the bad reading spot was by looking at the cam signal. Looked at the crank reluctor ring in that area, nothing appeared bad.
I then scraped and cleaned the block where the sensor sits figuring it may not be totally flush as this is rusty (appears to have been the issue). Put the first new sensor back in (maybe the second was defective), and it was a total flatline. Brand new no good.
Put the second new sensor in, crank and the spark tester lit up! Injector has pulse. I got it to kick on starting fluid, but it is backfiring out of the throttle body. At least I have something now. Thank you for your input, that definitely helped keep the gears in motion.

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