4 wheel drive "Auto" setting

['17 Sierra]

Duplicate post...see below.

['17 Sierra]

26 minutes ago, QuattroGinger said:

Came across this topic on a google search and found a lot of good info so figured I'd join the forum. My wife and I purchased a 16 Yukon Denali  in Nov 15. We were upgrading from a Terrain AWD. i myself am mostly a german car guy and my wife was Ford but we loved the terrain and it served us well so we stayed with GM when we needed something larger for the kids. One of  the big selling points the dealer was making to us is this "Auto" mode. They pitched the whole "you just leave in auto mode at all times and it will engage when needed". We live on east coast in MD and dont see much snow but do get it as well ice throughout the winter. So we left in auto mode.....6 months later we were on our way down 95 heading to South Carolina for vacation and the truck got stuck in 4wd while in auto mode. took to dealer, they said they reset the Transmission Control Module (TCM) as fix but to mention to our dealer when we got home to do a look over. well after we got home, the dealer said just mention it to us next time its in for service it sounds fine. then it got stuck in 4wd again so we took in, they preformed same fix and told us this was a known problem and not to use Auto mode ever again. havent used it since and haven't had any more problems with 4wd engaging. although i have had numerous other transmission problems and parts replaced. we havent even hit 2 years yet and barely 30k and truck has been in shop 7 times for transmission related issues as well lost the ability to use Auto mode (per our dealer) without expected problems. 

 

Anyone else experienced anything like this?

Welcome to the forum!

Auto 4WD mode is a great feature but there's no reason to leave it in that mode at all times. You will cause undue wear. Auto 4WD mode is easily confused with "All Wheel Drive" which it is not. When Auto 4WD is switched on,  basically you've engaged half of the 4WD system. There is a clutch system in the transfer case that is activated when the BCM detects loss of traction at the rear axle. It's good to keep A4WD on when there's heavy rain or some snow on the roads. When you hit dry pavement, you won't need to turn anything off as you should if you were in 4WD mode. 

[QuattroGinger]

16 minutes ago, '17 Sierra said:

Welcome to the forum!

Auto 4WD mode is a great feature but there's no reason to leave it in that mode at all times. You will cause undue wear. Auto 4WD mode is easily confused with "All Wheel Drive" which it is not. When Auto 4WD is switched on,  basically you've engaged half of the 4WD system. There is a clutch system in the transfer case that is activated when the BCM detects loss of traction at the rear axle. It's good to keep A4WD on when there's heavy rain or some snow on the roads. When you hit dry pavement, you won't need to turn anything off as you should if you were in 4WD mode. 

thanks. makes sense explaiend that way. Unfortunately this probably would of been a deal breaker for us at time of purchase had we known. My wife drives it with the kids primarily and the awd had helped her out quite a few times on previous suv so we were pretty set on having another awd type system. since this happened we have had diff lockers, trans valve body, torque converter, and tcm reset done 2 more times for shifting problems leading to heavy vibrating followed by truck shaking requring you to get on the brake to stop it. went back in shop this morning for 5th time. 

 

it has started getting cold here recently, i guess we will give the auto mode a try again during bad weather to see if it functions properly. when the truck isnt in the shop or having problems the ride was amazing for sure. hopefully everything gets resolved. 

[KARNUT]

I’ve had a few trucks with the auto mode. Whenever I encounter wet roads I’d just push the button and back to 2wd no problem when dry. Sometimes I’d forget to go back for a while on dry roads still never a problem.


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[rocc6]

I found my vehicle was in 4 wheel auto a few days ago while the dial was set to 2WD.  I have a 2017 GMC Sierra.  Last time I used the the 4 auto was around 3 months ago and really I only used the option during the winter months a few times.  Only reason I found it to be in the wrong drive mode was through pure luck when I was surfing through my menu displays and came across the Off-road menu. It displays the drive mode and showed the truck to be in AWD even though the dial was set to 2WD.  One click to the 4 auto setting and display showed 4WD shift in progress (which it already was in 4 auto) followed by a click back to 2WD position and received the same 4WD shift message.  It was now back to 2WD and matched the dial.  Took the truck into the dealership today for an oil change, and to find out what went wrong.  Big mistake, the service manager basically blamed me for not realizing the vehicle was in the wrong drive mode even though something had gone wrong with the switch.  I had notice the truck was driving differently but unfortunately I equated these differences to the lift I had done around the same time as the poor running conditions.  Truck runs great again, like new.  But, 3 months of poor fuel mileage 15.6L/100Km. 2WD 13.6L/100km, also I noticed my new BFG KO2 were wearing terribly on the front.  Service manager swears no extra wear to any internal and or external parts for driving in 4 auto for that amount of time.  I call BS.  I had them check the alignment, which I just had one done after the lift, to see if maybe the first alignment was screwed up and thats why the tires were wearing so badly but it came back spot on(they charged me 100 bucks just to see if it needed an alignment which it didn't) I feel the bad tire wear is from running in 4 auto for so long.  All I wanted to hear is something did go wrong and yes there will be some wear on vehicle parts that wouldn't normally be in 2WD.

Instead I am being called a Liar and told I am in the wrong because no codes came up after they plugged it into a computer.

I will be making a formal complaint to GM as to how I was treated by that manager specifically and also to the unresolved problem with the truck.

I am not saying driving full time in auto is going to destroy your vehicle but certainly it is adding wear and tear to things for no reason.

I would advise against driving these vehicles full time in 4 auto.

 

Good luck guys.

[Doobs41378]

Well they just replaced my differential under warranty and said it was because I left it in auto all the time. It was making an awful noise and when I took it out of auto the noise went away. It is all fixed now but they said it should not be left in auto.

[sgtMeowsteen]

8 hours ago, rocc6 said:

I found my vehicle was in 4 wheel auto a few days ago while the dial was set to 2WD.  I have a 2017 GMC Sierra.  Last time I used the the 4 auto was around 3 months ago and really I only used the option during the winter months a few times.  Only reason I found it to be in the wrong drive mode was through pure luck when I was surfing through my menu displays and came across the Off-road menu. It displays the drive mode and showed the truck to be in AWD even though the dial was set to 2WD.  One click to the 4 auto setting and display showed 4WD shift in progress (which it already was in 4 auto) followed by a click back to 2WD position and received the same 4WD shift message.  It was now back to 2WD and matched the dial.  Took the truck into the dealership today for an oil change, and to find out what went wrong.  Big mistake, the service manager basically blamed me for not realizing the vehicle was in the wrong drive mode even though something had gone wrong with the switch.  I had notice the truck was driving differently but unfortunately I equated these differences to the lift I had done around the same time as the poor running conditions.  Truck runs great again, like new.  But, 3 months of poor fuel mileage 15.6L/100Km. 2WD 13.6L/100km, also I noticed my new BFG KO2 were wearing terribly on the front.  Service manager swears no extra wear to any internal and or external parts for driving in 4 auto for that amount of time.  I call BS.  I had them check the alignment, which I just had one done after the lift, to see if maybe the first alignment was screwed up and thats why the tires were wearing so badly but it came back spot on(they charged me 100 bucks just to see if it needed an alignment which it didn't) I feel the bad tire wear is from running in 4 auto for so long.  All I wanted to hear is something did go wrong and yes there will be some wear on vehicle parts that wouldn't normally be in 2WD.

Instead I am being called a Liar and told I am in the wrong because no codes came up after they plugged it into a computer.

I will be making a formal complaint to GM as to how I was treated by that manager specifically and also to the unresolved problem with the truck.

I am not saying driving full time in auto is going to destroy your vehicle but certainly it is adding wear and tear to things for no reason.

I would advise against driving these vehicles full time in 4 auto.

 

Good luck guys.

I will almost guarantee you nothing went wrong with the switch..I'm betting you turned the knob AFTER you turned the truck off.

 

I did the same thing one day.

I had to use 4x4 to get down a trail to a lake I was fishing.

After I shut the truck off I realised it was still in 4x4, so I switched back to 2wd and went fishing.

When I got back out and onto highway I could hear the truck was running in 4x4 despite the knob showing 2wd.

Checked my off-road display and confirmed I was right.

 

The truck isn't smart enough to know that the knob was turned after the truck was turned off.

So when it starts back up it's still in 4x4 (4auto in your case).

 

Stupid design if you ask me.

[duquephart]

1 hour ago, sgtMeowsteen said:

I will almost guarantee you nothing went wrong with the switch..I'm betting you turned the knob AFTER you turned the truck off.

 

I did the same thing one day.

I had to use 4x4 to get down a trail to a lake I was fishing.

After I shut the truck off I realised it was still in 4x4, so I switched back to 2wd and went fishing.

When I got back out and onto highway I could hear the truck was running in 4x4 despite the knob showing 2wd.

Checked my off-road display and confirmed I was right.

 

The truck isn't smart enough to know that the knob was turned after the truck was turned off.

So when it starts back up it's still in 4x4 (4auto in your case).

 

Stupid design if you ask me.

 

Makes sense.

[rocc6]

I did recreate it by doing just what you explained, except in my situation the light on the shift knob was lit up on 2WD and when I shifted from 2WD to auto the 4WD shift screen came on.  In your situation the light still indicates 4 auto setting and when you select the auto setting it doesn't tell you it is shifting.

 

Whenever I shift that knob I wait until the shift is complete, for whichever drive I am going into.  Why would I shut my vehicle off and try to do a 4 wheel drive shift?

[adamj2121]

4Auto Shouldn't cause any extra tire wear, unless you are taking curves in rainy conditions at excessive speeds. Remember, the bigger and wider tires will wear faster, especially if you take turns quickly. Also, I found that the dealership couldn't align my truck with the lift and tires it was "within spec" but GM's specs are very generous. I had to take the truck to a shop that specializes in lifts to get my alignment done, I also had excessive wear on my BFG KO2s because the truck was aligned within spec by the dealer. I highly recommend finding an offload specialty shop and taking the truck there for an alignment.

[rocc6]

I will let ya know in 3 months if there is a difference in the wear of the fronts driving in 2WD vs 4 Auto.  I just rotated the tires at the same time as switching back to 2WD from 4 auto.

[adamj2121]

33 minutes ago, rocc6 said:

I will let ya know in 3 months if there is a difference in the wear of the fronts driving in 2WD vs 4 Auto.  I just rotated the tires at the same time as switching back to 2WD from 4 auto.

The BFGs will wear quickly if the truck is not in alignment, you should be able to tell within the next 500-1,000 miles.

[rjpoog1989]

1 hour ago, adamj2121 said:

The BFGs will wear quickly if the truck is not in alignment, you should be able to tell within the next 500-1,000 miles.

They will also wear quickly if you’re running the wrong psi.  Don’t go by the door sticker.  Need to get the load data from BFG and run at the recomended psi for the weight of the truck.  I have mine at 48psi but a lot of people run 50psi.  LT tires need higher pressure.

 

also, I do not recommend A4wd all the time or otherwise.  

[swathdiver]

Whether the front axle is engaged or not has no bearing on tire wear.  The AUTO setting is a safety feature, the front axle is engaged but nearly all power is to the rear axle unless the computers sense the need for some to be transferred up front.  My manual has no warnings about not using it for extended periods but common sense says the more one uses something, the more quickly it will wear out.  Having said that, what is the expected lifespan of a front differential engaged and not engaged?

 

I sometimes miss the simplicity of the manual levers!  

[adamj2121]

13 hours ago, swathdiver said:

Whether the front axle is engaged or not has no bearing on tire wear.  The AUTO setting is a safety feature, the front axle is engaged but nearly all power is to the rear axle unless the computers sense the need for some to be transferred up front.  My manual has no warnings about not using it for extended periods but common sense says the more one uses something, the more quickly it will wear out.  Having said that, what is the expected lifespan of a front differential engaged and not engaged?

 

I sometimes miss the simplicity of the manual levers!  

Unfortunately, simplicity is very uncommon any more. I remember my 02 had a manual 4x4 lever that activated an electrical motor to engage 4wd, the stupid electrical motor went out 3 times in a matter of 2 years. That made me miss manual locking hubs. haha