Intermittent starting issue 2011 Yukon XL Denali

[petethepug]

Since I last posted I had a breakthrough in our 09 Esky. It had intermittent long, slow crank, sometimes no start, sometimes studder accelerating out of corners. All intermittent, no related CEL.

It finally revealed itself as the crank position sensor P0355 and only gives a code randomly and simultaneously with the tacho not working.

If your exhaust manifolds are leaking plan on purchasing a set of OEM motor mounts, exh mani gaskets and ARP stud kit for the manifolds.

ARP do not snap, motor mounts are a breeze with exh mani out and you’ll be way ahead on price & longevity going OEM parts for another decade.

Deleting the z55 will make you want to get rid of truck. GM made z55 replacement struts guaranteed for life. They’re one & done now. Here’s the parts list from R/A to rebuild the front z55 on your Denali. Disregard the TPMS & z95 Magneride (Esky) struts and order z55 / autoride.

 

[Dadnali68]

Lots of good material here. Haven't had the issue in a few weeks. I'm wondering if it's a bad ground somewhere. I sprayed the whole underside with Fluid Film Black (got the $100 woolwax gun off amazon and a gallon of FF, I highly recommend this process for trucks that see salt like we get in NY.) And since then no issues. Maybe it's insulating a bad ground from water? Maybe it's low voltage and me driving it and keeping it on a tender when not driving is helping? Maybe I'm lucky? Either way. Also keeping the suspension stock. Found Arnott full strut assembly on summit racing for a reasonable price. I'll be doing them in spring once the snow and salt are gone. No sense rusting new parts!

 

[Dadnali68]

Updates. Truck went full no start. Would crank and crank but not start. Had it towed to a shop. They diagnosed bad relay to the PCM. Going to pick it up tomorrow. Side note, driver side heated seat stopped working. They found a burned wire in the pigtail under the passenger seat and 3 ohm resistance in the lower heat element and 13 ohm resistance in the upper heat element. Had them do the pigtail, sounds like I might need to do an upper heat element in the seat. Oh also they quoted me 2k to do upper and lower ball joins. So in the spring I'll be doing upper and lower control arms, struts, and sway bar links. All that will come out to less thank 2k and it'll be a fun little weekend or two in the garage. Curious if you all think this relay at the pcm was the actual issue or if it's a symptom of a deeper issue.

 

[Foggy]

I would take some time when you are doing other items and really check
the body/ frame grounds... I've not had issue but it's been
discussed a bunch on this forum. They corrode over time and cause
all sorts of very weird unrelated issues to show up

 

[petethepug]

Nice shop delving into the heated seat for you. Powertrain Control Module and diagnostic probably wasn’t that pricey.

Check your under hood fuse box attaching bolts for torque. Maybe your shop already did. If the shop doesn’t look like they were in there, check the back of the fuse box board if more issues come up.

Good truck for the winter drive. When you get a chance lower the spare tire and coat the area and the suspension control module that likes to rot out.


Oh yea, update edit/ the title to RESOLVED (WIN!)

 

[Dadnali68]

Really nice shop, not my normal but I'd work with them again. For the seats they suggested a new module. The one under the seat. Does that need to be programmed to the vehicle? I'm finding conflicting results.

 

[petethepug]

If it’s a factory new module, Yes

Preloved module, No

Gotta love 07-14. 15-20 is either a no go or reprogram.