Auto 4WD Shuddering

JME454 · September 9, 2020

Anyone else experiencing drivetrain vibrations in auto 4WD on flat pavement above 25mph? I was told by the dealer this is a known issue with no current resolution. Haven’t asked for TSB yet. They said GM recommends leaving in 2WD until wheels slip. If I’m already losing traction why would I use auto instead of 4hi? The system on my older Tahoe was seamless.

Gangly · September 9, 2020

I haven't had this issue but I don't drive much in Auto. I agree with your comment though, if you knew you were going to be traversing slippery terrain then you would obviously have it in 4WD, but the purpose of Auto is to ensure you have 4WD when a lack of traction occurs but is unexpected.

Good luck and please let us know what you find out.

JME454 · September 12, 2020

Got the truck back from dealer today. They had it for two days for the complimentary oil change and to flash the brake module. Their only 4wd tech is booked for three weeks. I asked advisor for the bulletin for the auto 4wd they told me about. They went to the service manager, came back and said actually it’s in the owners manual that states not to use auto 4wd on pavement and causes vibration. I reminded them that it states auto 4wd is for variable conditions and leaving in 4hi on pavement may cause vibration to be felt. They said I could leave my truck there for three weeks if I wanted but other trucks with this issue have come in and nothing was done. I may reach out to another dealer.

The vibration in auto isn’t bad, more of resistance on the drivetrain that’s is heard and felt. Seems like it’s engaging because it is sensing slippage maybe. Don’t plan on using auto 4wd much so not a big deal. Just don’t want to accept a flaw especially if not all our trucks are experiencing this. No more launches in auto 4wd for now damn it!