4 wheel drive "Auto" setting

Z45 · January 25, 2016

I leave mine in Auto year round. On some highway trips in the warmer months, I will put it into 2wd since the CC will be set. I really don't notice any difference, I am not a fast driver with my truck so my MPG is somewhat the same in either mode.

I always drive in AUTO during winter, from Nov-April. Last week I drove 360 miles (RT) in AUTO on snow covered roads. Today I have to drive over to Superior WI and back, round trip 450 miles and it will be in AUTO if the road are slippery, snow predicted all the way there and back. Only time I take it out of AUTO in the winter is when roads are 100% clear and dry. I have not driven on completely bare roads in 1.5 months. I rarely even use 4wd because AUTO gets me around just about everywhere.

I know people who have a 4wd truck and they really should not even buy one. One fella will only use 4wd when he goes to hunting camp, he will sit at a stop sign in 12 inches of snow and spin the tires to get going. I once gave him heck for not using at least AUTO and all he did was cry that it burns to gas.

My 1st 4wd was a new 1975 Chevy Blazer and I have owned a GM 4wd every year since, on my 11th GM 4wd truck since 1975.

PS-For business reasons, I replace my truck anywhere from 3-5 yrs (occasionally 2 yrs if incentives are good) or when the warranty runs out. Like my current truck, GM veterans program discount and rebates took 10k of MSRP so I sold 2012 and ordered a new one. That way I pay less for a new one by selling or trading it while it still have a good resale value.

SouthPawCO · January 25, 2016

After reading this thread, I decided not to run in Auto 4WD all the time. After checking my 'off road' setting in the gauge display (shows which tires have power and degrees the truck is tilted, not sure what it is called) it showed all four tires had power to them in auto. I do use it when the roads call for it but if it isn't needed, I will keep it off from here on out. I will take a picture of it later today if I remember.

redwngr · January 25, 2016

OK so I have a simple question as most of this thread answered what I was wondering. Last night since I live in the northeast we got some good snow. Had to go to the store and since this was my first 4wd , I've had an awd, I wasn't sure if I needed 4hi or auto being there was only 2 inches on the ground. So I threw it in auto. My thoughts after reading this is 2wd anytime its nice or even raining as I let my foot control the truck and speed and 4hi if I have some good snow on the ground. If its snowing or ice or I'm off road 4 hi. My question is 2 fold...if I'm in 2wd and feel the need for 4.. Do I need to stop to switch or can I keep driving and go to 4hi? Also... I know this is more of an opinion and I know I'll get 10 different answers...but to not ruin the front axle when is it OK to put it in 4hi? Is a light dusting or say and inch of snow OK or is that to little as around here the main roads get plowed so they're wet and slushy but the back roads are usually covered with a skim of packed snow?

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You do not need to stop to switch. Let it coast, switch it, and when it shows the shift is completed you're good to go.

From the OM:

"The vehicle can be shifted between 2 H and 4 H while the vehicle is

moving. In extremely cold weather, it may be necessary to stop or slow the vehicle to shift into 4 H."

Find an empty, paved, parking lot somewhere. Put it in 4H and drive around a bit. Make some turns. You will feel, and might hear, the reason that 4H is not recommended on 'dry' surfaces.

Whenever it is slick enough that you decide to use 4H, remember that it while it might improve how quickly you can accelerate, it will not help you stop quicker.

FWIW, I've driven 4wd gm trucks for more than 20 years, and until my 2015 none have had the 'auto' mode. I still never use 'auto' as I prefer to know whether it is 'in' or 'out'.

Jeff5347 · January 25, 2016

^^^^Oh I did that a week after I got the truck. Was in sparking lot on dry pavement. Tree it in 4hi and moved forward ...OK. ...backedup but I had the wheels full right locked. Felt like I was pulling a stump as it was not wanting to move easy. I later found out it was due to the front axles locked and there wasn't any way for the tires to rotate at their own speed which I also found out is a baddd thing. Learned my lesson. No 4 on dry roads lol

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mike5511 · January 26, 2016

I throw mine up in 4H every now and then when I'm leaving the house, and going straight, just to let everything move a little.

tnchevy · January 26, 2016

I do the same thing, put in in 4hi when I am on straight roads for 5 to 10 minutes a couple of times a month. I got in this habit years ago when we used to have a tacoma where it stated in the owners manual that it need to be driven in 4wd so many miles each month.

15 Z71 · January 26, 2016

I seriously can't believe there is 9 pages on this.lol

amfr · January 26, 2016

I absolutely love this thread. This is the epitome of the internet. I live in Florida and have only put my truck in 4 hi when I was pulling my boat out on muddy and questionable terrain. Rain for days all 2wd. It's about the driver imo. What ever makes you comfortable and safe. There is choices for each specific person. Auto all day won't hurt your truck it's a truck for God's sake. And your front wheels always spin so why not add in the transfer case and engage the drive train? To put it simply what ever you feel you need is right.

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BigBrew · January 29, 2016

So I live in Michigan, and we've had some snow this year. Someone needs to explain to me how to get these trucks to slide around. I tried to nail it around a corner a couple nights back and slide the ass out as I've read on this thread, and I just can't seem to do it. My foot is all the way to the floor and the truck is taking over and well not letting me crash. WTF are you guys talking about that you need to be in auto to keep the truck in control. Are we suppose to be running these in auto with the traction control off or something?

j-ten-ner · January 29, 2016

so long

j-ten-ner

Badass69 · January 29, 2016

I don't like auto and if it wasn't a standard thing I wouldn't bother with it. If I need 4wd... I flip the switch to 4hi and otherwise it can stay in 2wd. I really have no problem maintaining my trucks control at 75 mph on ice/snow/rain in 2wd and haven't for the past million miles or so I have driven. I don't like stabilitrack either but thankfully my truck just powers right through that rubbish and it accomplishes nothing.

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SierraMyst · January 31, 2016

Could someone answer me this?

We got the huge blizzard up here in the northeast these last couple of weeks.

My driveline is super smooth in 2wd.

During the heavy snow, I used 4H, no issues. Truck drives smooth. But it was slow driving through heavy snow. I'm a first responder and go into work rain, snow, sleet, shine.

A week after the snow ended and everything started melting and refreezing I switched into Auto mode. I quickly noticed a vibration in the driveline as I accelerated through 30-40 mph with medium to heavy throttle.

If I kept the throttle light there was no issues, and during the first refreeze that what I did. Drive slow.

But as the snow started to clear out and driving began to increase in speed and acceleration more and more, I noticed this vibration more and more. It's smooth from 0-28ish then it starts and goes full shakes from 30 - 40 mph and goes back to smooth again after 40 mph and at highway speeds.

Is something happening from 30-40 mph in Auto mode with medium to heavy acceleration that is causing this vibration?

I tested this about 10 times switching back and forth between Auto and 2WD, and it only happens in Auto.

Is this normal?

j-ten-ner · January 31, 2016

Are your wheels clear of all snow and ice?

so long

j-ten-ner

SierraMyst · January 31, 2016

Are your wheels clear of all snow and ice?

so long

j-ten-ner

Yes sir.

amfr · February 1, 2016

Could someone answer me this?

We got the huge blizzard up here in the northeast these last couple of weeks.

My driveline is super smooth in 2wd.

During the heavy snow, I used 4H, no issues. Truck drives smooth. But it was slow driving through heavy snow. I'm a first responder and go into work rain, snow, sleet, shine.

A week after the snow ended and everything started melting and refreezing I switched into Auto mode. I quickly noticed a vibration in the driveline as I accelerated through 30-40 mph with medium to heavy throttle.

If I kept the throttle light there was no issues, and during the first refreeze that what I did. Drive slow.

But as the snow started to clear out and driving began to increase in speed and acceleration more and more, I noticed this vibration more and more. It's smooth from 0-28ish then it starts and goes full shakes from 30 - 40 mph and goes back to smooth again after 40 mph and at highway speeds.

Is something happening from 30-40 mph in Auto mode with medium to heavy acceleration that is causing this vibration?

I tested this about 10 times switching back and forth between Auto and 2WD, and it only happens in Auto.

Is this normal?

Maybe some salt got in your front drive train