I need your brains (Cam/Crank Correlation Problem)

Gary M

Original poster
Jul 12, 2012
Heya all,

I've had some pretty bad luck with my Envoy (all the usual things have gone wrong, and then some) - this latest one is going to be the make-it-or-break it problem: I'll either fix it or just give up, drive it to the scrap yard, and be done with it.

I do all my own work (I was an apprentice mechanic 30 years ago) so at least I've saved some cash there.

OK, the latest crisis:

I had the usual OBD codes for cam actuator and sensor problems, so I swapped 'em both out. I cleared the codes, re-ran the scan and it came up clean.

I started the truck, re-scanned and a P0017 came up as pending.

I shut it off, cleared the codes, re-scanned and it came up clean (of course).

I took it for a drive, scanned and again had the P0017 pending.

I cleared the codes, let it sit overnight, started it up and the CEL is on with a hard (no longer pending) P0017 now.

My question: Is there a common cause, or something that I'm overlooking, that causes this behaviour?

I'm familiar with the list of "official" possibilities (and there are some (crank end play for example) that I don't even want to consider). I'm hoping that this happens all the time with CPS/CPAS swaps and someone is able to say "Oh, yeah, 99% of the time the "X" wire leading to the CPS harness breaks at "Y" position" or something like that.

One thing to note: Although I don't think I damaged the CPS and CPAS wiring, this behaviour (codes setting - 1st intermittent, then constant, over about 2 months) started immediately after I swapped the exhaust manifold ... Maybe there's a wire down there somewhere I disturbed?

I guess I'm asking for some brainstorming here.

Thanks in advance,



EDIT: Forgot the basics - 2005 Envoy SLT, about 180,000km (108,000 miles) on the truck, about 110,000km (66,000 miles) on the 4.2L I6 mill. Bought it off a corporate lease in 2007.


Mar 3, 2012
Gary M said:
....this behaviour......started immediately after I swapped the exhaust manifold ... Maybe there's a wire down there somewhere I disturbed?.......

That's where I'd be starting my investigation.


Dec 4, 2011
Damage to the CPS wiring or connector seems common while working on the passenger side of the engine. I would check the reference signal

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