2020 Denali 3500 wont start

Duallyboy26 · September 10, 2020

Hey guys so I purchased a 2020 GMC Denali 3500 about 5 months ago. Within the first 30 days, the truck failed to start. All the service lights came on. Finally when it started 45 min later, the check engine light stayed on. I took it to the dealer the following day. They stated it’s throwing no codes and can’t duplicate the problem. I took my truck back home following day. In less then 30 days, it happened again. I took the truck back to dealer and once again stated no codes and can’t duplicate problem. Then GPS stopped working. WiFi stopped working. Loud clicking sound coming from behind driver seat in roof. Now 60 days later truck won’t start again. They also stated again they can’t duplicate the problem. Luckily I took video footage as they stated “if you didn’t provide us these videos we would have never believed you.” Got my attorneys involved and were aiming for a full refund lemon law. Not to mention the truck cams with major dings, dents and trash under the factory paint. This has been my third denali 3500 HD. Started with a 17 then 19 and of course had to get the new body. Please let me know if anyone has had a similar case. Thank you

Duallyboy26 · September 10, 2020

MTU Alum · September 10, 2020

It looks like low battery to me.

#iworkforGM

shadow gray 2020 hd · September 10, 2020

Had a strange issue happen here with my new truck last week. Was sitting in sam's club parking lot, picked up a online order that was brought out to me. The girl used the scanner right outside my passenger side back door while loading stuff. Then I went to start and nothing. The truck would not recognize my fob. Ended up taking a few minutes to figure out to put the fob in the pocket under the seat and get it going.

Guessing in my situation the scanner the sam's employee used must have somehow interfered with the system in the truck and put it into security mode. Electronics systems on these trucks should not be this fickle.

Duallyboy26 · September 10, 2020

1 hour ago, MTU Alum said:

It looks like low battery to me.

#iworkforGM

Even though letting it sit for 45 min it starts up just fine after and works perfect for 30-60 days?

Tomato · September 10, 2020

Check the under-hood fuse box bolt torque - per the TSB...

VolVet03 · September 27, 2020

Just got my new 3500 AT4 home tonight with the gas motor. Brought family out to go for a ride, pushed button to start, it cranked and died threw CEL. I cranked two more times tried to start then died. We let it set 5 minutes tried again started up and gas smell from tail pipe super strong like it was flooded. Got the app notification service engine and transmission system within 1 day. Lifetime Ford convert, off to a bad start.

Will go out tomorrow and check fuse box torque situation.

Tomato · September 27, 2020

9 hours ago, VolVet03 said:

Just got my new 3500 AT4 home tonight with the gas motor. Brought family out to go for a ride, pushed button to start, it cranked and died threw CEL. I cranked two more times tried to start then died. We let it set 5 minutes tried again started up and gas smell from tail pipe super strong like it was flooded. Got the app notification service engine and transmission system within 1 day. Lifetime Ford convert, off to a bad start.

Will go out tomorrow and check fuse box torque situation.

Just remember the spec / TSB calls for 53 Inch-pounds. I saw another post where someone mentioned foot-pounds...

VolVet03 · September 27, 2020

2 hours ago, Tomato said:

Just remember the spec / TSB calls for 53 Inch-pounds. I saw another post where someone mentioned foot-pounds...

Yes, I saw that thanks for reminder though. Heading into town now to hunt one up. Green indicators are up but I’ll post back when I find an in/lb wrench. Hopefully I can just borrow one at O’reillys or Autozone.

VolVet03 · September 27, 2020

Okay quick trip to Harbor Freight for 20$ inlb wrench and bolts are tight. They were extremely loose. Think it was a 7 mm socket.

CEL is gone(was gone this morning when I went out to start it) and everything seems fine for now, if it goes haywire again I’ll post.

Gyctom · May 26, 2021

Hello. This exact thing just happened to me. I was sitting in the truck, engine off , while waiting for my wife to go shopping. I finally go it started. I noticed the orange light on the button for the mirror lights were on. I turned it off, locked the truck and waited for the truck to 100% shut down, no lights at all on the dash. I unlocked the truck and it started right up. I do have a check engine light as well and I’ll pull codes in the morning.