Intermittent starting issue 2011 Yukon XL Denali

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Dadnali68

Dadnali68

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No security light flashing I assume not so I would look into the neutral safety switch
on the transmission and see if the inputs are correct. If it thinks it's in the wrong gear it won't start.
No security light. I have suspected NSS but haven't confirmed anything. Also still haven't had an issue since posting this. Y'all might be good luck lol.
 
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Dadnali68

Dadnali68

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While I have all this great attention, I'd like to ask, are there some good threads to read about AFM/DOD delete, Z95 suspension repair or delete, and spare tire usage on the AWD models? My current engine is strong but it's starting to let exhaust manifold bolts go. I'd like to get a used motor and do the delete myself and drop it in once she get a little more clapped out. My front struts are bouncy and I'd like to replace them with Z71 style ranchos or bilsteins but not sure of the impacts on the Z95 megnerides. And my truck has stock 20s and the spare is an 18. Want to know if it's safe to use in an emergency with the AWD or if I'll blow the differential out with the size difference. Suggested reading material is appreciated!
 
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Dadnali68

Dadnali68

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Also for those who have suggested I get a tech2. My dad gave me his Foxwell scanner. He used it like 10 years ago to diagnose a bad BCM on his 12 Sierra, so I'm hoping I have the necessary features to do what a tech2 would do. Will update as I use it.
 

Geotrash

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While I have all this great attention, I'd like to ask, are there some good threads to read about AFM/DOD delete, Z95 suspension repair or delete, and spare tire usage on the AWD models? My current engine is strong but it's starting to let exhaust manifold bolts go. I'd like to get a used motor and do the delete myself and drop it in once she get a little more clapped out. My front struts are bouncy and I'd like to replace them with Z71 style ranchos or bilsteins but not sure of the impacts on the Z95 megnerides. And my truck has stock 20s and the spare is an 18. Want to know if it's safe to use in an emergency with the AWD or if I'll blow the differential out with the size difference. Suggested reading material is appreciated!
Keep the Z95 suspension. Replacement GM or Arnott rear air ride and front mag ride shocks are relatively inexpensive on rock auto (compared to dealer prices), as is the compressor if it needs it. We've seen folks go to regular shocks and regret it, going back to the factory mag ride/air ride setup. It's an incredibly effective and reliable system.

On the spare, if you run the calculations, it has the same diameter and circumference as the 20" wheels and tires, so it's safe to use in a pinch. I replaced my spare on my '07 with a new tire because the original was 16 years old at the time and I didn't trust it if I ever had to use it on a trip.

Exhaust manifold bolts are easy fixes when you come at them from the side after letting them soak with penetrating oil overnight. If you break any or can't get the stubs out, they sell a drilling and extraction template on Amazon that works great so you don't damage the cylinder heads.

Lots of threads on here with advice and learnings for AFM/DoD delete. I'm running a Cam Motion Stage 2 truck cam (3-bolt) in my 2012 XL Denali that I love.

Only other things I would recommend is 1/ only running premium fuel in that 6.2L, and 2/ replace the torque converter with a billet unit that has a stronger lockup clutch. And, 3/ Get that thing Blackbear tuned! Some of the best money I've spent. It will wake up the truck, make the transmission last longer, and they can tune out AFM, too.
 
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Dadnali68

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Well all, my luck ran out. Had to jockey cars around the driveway today. Fired it up remote start. No issue. Ran for 10 minutes, shut down for an hour. Tried to remote start, nothing. Got in, turned key, fired right up but had a CEL. Code P1682. Cleared the code, moved the truck shut it down. Realized I was off the driveway, couldn't see it due to snow! Went to fire it again and it cranked and cranked with no start. Tried again, long crank no start. Tried again, it fired but was lopey. Check engine light, reduced power warning, stabilitrac warning. Got the trucked moved and shut down and went in to watch Sunday night football. Y'all got any ideas what the hell my truck did?
 

petethepug

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In the morning or tonight, disconnect and slow charge the battery. If DTC goes away you may have a battery that’s ready to let go.

Next step would be to slow charge overnight/ disconnected again and have it load tested at part shop.

Your truck has z55 autoride and is one of the best riding trucks they’ve ever made on those 20’s.
 

Doubeleive

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Well all, my luck ran out. Had to jockey cars around the driveway today. Fired it up remote start. No issue. Ran for 10 minutes, shut down for an hour. Tried to remote start, nothing. Got in, turned key, fired right up but had a CEL. Code P1682. Cleared the code, moved the truck shut it down. Realized I was off the driveway, couldn't see it due to snow! Went to fire it again and it cranked and cranked with no start. Tried again, long crank no start. Tried again, it fired but was lopey. Check engine light, reduced power warning, stabilitrac warning. Got the trucked moved and shut down and went in to watch Sunday night football. Y'all got any ideas what the hell my truck did?
I would read thru this and see if anything rings a bell
 

j91z28d1

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very general but sounds like ign power issues.



if it sets the code again. the freeze frame data could be helpful
 
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Dadnali68

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Well folks, get ready for this one. Went out today to look at the truck, Crack and no start twice. Fired third time but all warning lights on. Collected codes in pictures. Erased codes. All warning lights went away and idle returned to normal. Shut it down, started right up, no CEL, no warnings. I'm tossed. Mechanic thinks bad battery. I think it's something more but I will start using a battery tender on it since it sits a lot between drives. I should also mention sometimes volts are below 14 and sometimes they are above 14.1000003014.jpg1000003015.jpg1000003016.jpg1000003017.jpg1000003018.jpg
 

Doubeleive

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the hvac codes are likely unrelated but there is a TSB out there for the transmission harness having some of the pins not inserted properly and it causes a whole host of issue's, might be a rabbit hole but not hard to check out also.
some of those codes and your issue's match the known problems reported in the tsb
 

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