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2001 Silverado 2500HD LB7/ZF6 4x4
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Discussion Starter #1
Howdy Yall,

longtime lurker here but I can’t seem to find what I’m looking for through searching. I just picked up a 2001 2500HD LB7/ZF6 recently and its been great! Used to have another ‘01 with the ally but alas it died an untimely death, but I digress...

The check engine light came on, so I bought the BAFX obd2 adapter and Torque Pro (Balance rates are golden btw!) and pulled the code P1345 “Crankshaft Position (CKP)-Camshaft Position (CMP) Correlation”.

Now my question is, since our timing is gear driven, it would have to be either the crankshaft position sensor or the camshaft position sensor, yeah? There wouldn’t be anything else that would cause this code is there? I would think if a sensor was bad that would throw its own code, anybody have any experience with this? Truck drives awesome other than the rare time it will stumble for a sec, trip the code, then go back to normal.

thanks in advance! -Jesse
 

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Welcome to DieselPlace

(y)
 
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Thank You!
I would start by inspecting the Crank sensor wire harness looking for any rubbed through wire, corrosion, broken wire, etc.
Make sure the connection is clean and tight.
Is your truck equipped with the Allison or manual trans?
 

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2001 Silverado 2500HD LB7/ZF6 4x4
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Discussion Starter #5
Thanks I’ll take a look at that after work. It’s a manual trans
 

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Thanks I’ll take a look at that after work. It’s a manual trans
It can be a few things like excessive crankshaft end play
The Flywheel in the manual trans may be causing a false crank sensor code.
The dual-mass flywheel has been known to stick.
Loose reluctor wheel on the crankshaft or intermittent connection

I am leaning more to a worn through wire issue or faulty sensor..
The cam sensor might be shorting, causing the false code to appear.
Try clearing the code and move the wires around with the engine running to induce the code to appear.
 

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2001 Silverado 2500HD LB7/ZF6 4x4
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Discussion Starter #7
I took a quick look after work at what I think may have been the wires? Will have to double check, but without pulling the fan I definitely can’t wiggle anything around when the engine is running. None of the wires anywhere in the truck look worn or corroded though.

Unless the issue gets worse I’m just gunna leave it and keep an eye on it for now, but next time I have a free day I may pull the fan and give everything down there a good once over, pull the cam sensor and check the reluctor ring and such. Not a lot of time on my hands right now but now I have a good list of stuff to check on! Thanks OKDually!

The truck only has 230k miles on it so hopefully it’s not anything too major! I noticed this morning the only time it did it was under really light load, like right at that point when you’re cruising along and you’re just BARELY touching the accelerator and it can go between fueling and engine braking instantly. Once I gave it some fuel it was fine, and it only happened once, but it did trip the SES light...guess the solution is don’t baby it around haha
 

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02 2500HD LB7
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Hate to say it but based on your latest info it sounds like a loose reluctor wheel somewhere vibrating occasionally causing the computer to see the cam and crank signals as out of phase.
 

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2001 Silverado 2500HD LB7/ZF6 4x4
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Discussion Starter #9
So possibly a new development,

This morning, I went to start the truck and it ran for maybe 10-15 seconds then it shut off. Went to fire it up again and it cranked for like 3 seconds before It started (which doesn’t sound very long but when it normally fires up after like .5-1 seconds it was significantly longer). It drove fine and started just fine repeatedly all day after that incident.

fast forward 9 hours and it starts stumbling again, seemingly out of nowhere because it drove fine for 250 some odd miles through California’s central valley and into the sierras, through towns, up to 80 mph, from idle to 3k rpm over and over, through the mountains up to 7200 feet at Donner Summit...and then a couple miles outside of Truckee is when it started acting up again.

one thing I’ve noticed is when the temp gauge on the dash is under say about 180-190 is when it will act up if it does (in the mornings when its still cool out, or like tonight, higher elevations at night), if its running over 180ish (mid day and 90s outside, fan clutch engaged, Ac on) it hasn’t been having any of these issues. Idk if any of that is coincidence or if that may be a clue to some other factor? Figured if anyone would know, yall would!

Thanks in advance guys, hope yall are having a good weekend

edit: also, it did not trip the SES light tonight, despite stumbling many times over the next hour and 40 some odd miles of driving after it started acting up again

edit #2: it idles just fine, 600 rpm and no loping or anything...
 

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02 2500HD LB7
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Can your code reader see Pending codes? That would help to see if the computer noticed one sensor is going off but not enough to trigger a full light yet?
 

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2001 Silverado 2500HD LB7/ZF6 4x4
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Discussion Starter #11
Unfortunately the only code pending or active is P1345.

Another hard start this morning, it kept dying/wanting to die until I held the rpm's around 900 for about a minute then it idled fine afterwards. it would stumble a bit but not too bad, restarted just fine after 15 min of driving too. I poked around under the truck a bit and all the connections feel fine, I noticed that the fuel primer was not hard, not quite soft, hardened up after about 5-10 pumps. no wetness or anything around the filter head but if it was sucking air, could stumbling from that even trip the cam/crank correlation code? just trying to cover all the bases before I start tearing into the truck on the family vacation to check the cam sensor hole for reluctor wheel play.
 

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02 2500HD LB7
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Wouldn't hurt to do the filter head anyway and see if anything changes.
Did mine last year and the seals & o-rings had all seen better days. Also get the 2 rubber lines that go out to the filter head, mine were all cracked when i took mine apart and had to get them too.
 

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This thread has a picture of the problem I had. Here we go again......
Started out as a rough run, then a no run.
 

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2001 Silverado 2500HD LB7/ZF6 4x4
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Discussion Starter #14
You nailed it Okdually! I ended up taking it to a diesel shop and in addition to the cam sensor being bad, they found bad wiring in the crank sensor pigtail that I missed. Back in action and its running great! Hopefully that was the extent of my problems but thanks to yall, if it acts up again I know what to look for. Thanks again for all yalls replies and help!
 

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You nailed it Okdually! I ended up taking it to a diesel shop and in addition to the cam sensor being bad, they found bad wiring in the crank sensor pigtail that I missed. Back in action and its running great! Hopefully that was the extent of my problems but thanks to yall, if it acts up again I know what to look for. Thanks again for all yalls replies and help!
Glad you have the issue resolved.
Thanks for giving us an update!

(y)
 
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