4 High won't engage when the wheels are turned

sbweld · February 6, 2018

Hi all,

I have a 2015 Sierra 1500 SLE (Crew Cab, All Terrain) and was unable to accelerate today after I pressed the gas to turn at a snowy intersection. All I could hear was a weird noise under the truck that sounded like it had something to do with the driveshaft. I was just sitting out there in the middle of the intersection and wasn't able to move until I manually changed it into 2WD.

I found an empty parking lot to try and replicate it and I found that when I had the wheels turned and switched it from AUTO to 4H the same thing happened. I suspect that when I was in auto at the snowy intersection the truck tried to go into 4H but couldn't because of something to do with the front wheels being turned.

Has anyone heard of something like this ? Any ideas on what it could be and why the wheels being turned would make a difference?

Dealer wasn't helpful last time this happened because they couldn't replicate it but I think I should be able to replicate it for them now.

Trish77 · February 7, 2018

I have the 2016 SLT crew cab all terrain as well as this was one of my complaints when I took mine to the dealership for the 4th time! They told me it was normal and that the sounds were from snow being compacted around the area. However there was not much snow on my truck. I still don’t think it’s “normal”. The sound is definitely like something isn’t working right!

Sent from my iPhone using Tapatalk

BigBadSierra · February 7, 2018

Full 4x4 locks the drive-line into full time drive not the same as Auto. Auto uses a clutch type system so the wheels have some drive and can still slip.

In full 4x4 with the wheels locked and all spin at the exact same speed so you can bind up the system up if they are not allowed to spin.

If your feeling the bind you are getting to much traction and need to switch back to auto.

I only switch it on when the road is at 100% no traction.

The 4 Auto lets me know though as truck starts sliding all over so I need more drive.

aseibel · February 7, 2018

lets see if i understand this:

you were driving in 4 auto, drove into an intersection and stopped with your wheels partially turned and couldn't move? Were your back wheels spinning? Then you shifted back to 2HI and could drive again?

The 4HI has to mechanically engage the front axle. I always shift when either sitting still or slowly coasting straight ahead. Trying to do this while turning doesn't help anything. It takes a few seconds to engage if things aren't lined up. I'm guessing your scenario just wasn't letting everything click.

sbweld · February 7, 2018

Thanks for the feedback on this. My issue occurs when the transmission is in Auto and I’m stopped with my wheels turned to the left or right at an intersection. If the truck senses that it’s slippery when I hit the gas and it tries to engage 4WD but it can’t. All I get is a loud noise from underneath and little to no acceleration. There was one occasion where I was a sitting duck in oncoming traffic while the truck was trying to figure it out.

If everything had to be lined up (ie wheels straight) for 4WD to engage, doesn’t that pose a bit of a flaw with the auto setting ?

aseibel · February 8, 2018

that doesn't sound right then. If you're already in auto when you hit the gas, there is only 1 clutch that needs to grab the front driveshaft. If your truck isn't doing it right away something is wrong. the 4 auto setting kicks in almost instantaneously like you wouldn't even know you weren't in 4wd.