Driving in 4wd

[TX14Z71]

So are you saying that in Auto someone can't back up a trailer or was that just a problem you were having with your Avalanche?

[kstruckcountry]

At low speeds offroad it's probably better to use fulltime 4x4 anyways, especially with a trailer. Sounds like at the low speed his Avy couldn't figure out whether to stay engaged or not. I backed up using it last week without any issues. In steep parking spots it's really nice.

[tutiii]

Thanks, I put my truck in neutral and switched from 2wd to auto to 4wd then back to 2wd. and i was good to go. talked to my son who drove it last in the snow, he said he thinks he switched it to 2wd then turned the truck off, he didn't wait.

thanks again for your help

[hiramh]

Has anyone tried to climb a hill in 4 wheel low. Mine surges, goes then stops. According to the dealer they are designed not to operate properly in 4 wheel low climbing a hill. My 2009 had no problem with the hill in 4 wheel low.

[Cap'n Pete]

So are you saying that in Auto someone can't back up a trailer or was that just a problem you were having with your Avalanche?

Maybe it was an isolated issue with my Avalanche, I don't know? It just seemed that "Auto" was having a hard time dealing with the snow/ice that I was on, while backing up, so kept disengaging every time the truck would start to move (as if to say, "there, you're moving now, I'm done"). By going into 4Hi, then 4WD engaged fully, so the front tires were there for me 100%. Again, don't know if that was a "flaw" in the system, or what, and I can't say if the same will or won't happen with the new '14 model. I've used Auto once so far, and it performed fine (but the condition wasn't the same).

 

At low speeds offroad it's probably better to use fulltime 4x4 anyways, especially with a trailer. Sounds like at the low speed his Avy couldn't figure out whether to stay engaged or not. I backed up using it last week without any issues. In steep parking spots it's really nice.

Exactly. Due to backing up a trailer on a very slippery surface, I was trying to push extra weight, not just get the truck moving. ALSO (forgot the important part I guess) there was a small "hump" that was I trying to get the truck/trailer over (the low remains of a snow bank) so I think overall, it was too much for the transfer case clutch to manage. It just needed to be FULLY ENGAGED. Once it was, it worked fine.

 

So whether or not that was a one-off problem with the truck, or the circumstance, I've determined that Auto is best for normal driving conditions, but use 4WD (Hi or Lo) for times when you're WORKING the truck (ie: maneuvering a trailer, plowing, off-roading, etc).

[JCthebigTree]

Has anyone tried to climb a hill in 4 wheel low. Mine surges, goes then stops. According to the dealer they are designed not to operate properly in 4 wheel low climbing a hill.

Why would it be designed not to operate properly?

 

 

As far as trailers and AUTO... I've also noticed less than ideal performance backing up trailers in snow... Its almost like the system is designed for forward motion and just gets 'confused' backing up, especially with trailers. I've always thrown my GM's in 4 hi when backing up in sloppy situations.

[MikeNH]

Auto 4WD works based off ABS sensors and I'm not sure that ABS works in reverse. I know it didn't on my Tacoma as I slid down the driveway of my old apartment backwards once due to ice.

[Cap'n Pete]

Auto 4WD works based off ABS sensors and I'm not sure that ABS works in reverse. I know it didn't on my Tacoma as I slid down the driveway of my old apartment backwards once due to ice.

Wheel speed sensors just send an electrical pulse (electromagnet and a reluctor ring). They should work in either direction. The only reason the system "may" not work in reverse is if the computer specifically blocks it while in reverse, but it should have nothing to do with the speed sensors.

 

But that being said, Auto 4WD obviously WORKS while in reverse. I may have just been the specific scenario I was in that it was acting up (or the system had a fault/flaw, OR it was an older truck and the system wasn't as fine-tuned as it is now?! ...dunno!!)

[MikeNH]

Auto 4WD works based off ABS sensors and I'm not sure that ABS works in reverse. I know it didn't on my Tacoma as I slid down the driveway of my old apartment backwards once due to ice.

Wheel speed sensors just send an electrical pulse (electromagnet and a reluctor ring). They should work in either direction. The only reason the system "may" not work in reverse is if the computer specifically blocks it while in reverse, but it should have nothing to do with the speed sensors.

 

But that being said, Auto 4WD obviously WORKS while in reverse. I may have just been the specific scenario I was in that it was acting up (or the system had a fault/flaw, OR it was an older truck and the system wasn't as fine-tuned as it is now?! ...dunno!!)

 

 

I know how the sensors work, but I clearly remember the Tacoma not doing a damn thing as I slid down the driveway backwards and nearly hit the dumpster.

 

I can't say I've tried auto 4wd in reverse. Frankly after seeing how the truck plowed ahead when coasting in auto I've generally been using regular 4 high. Even with a small amount of snow on the ground there's enough to allow slip and not bind things up. I've only used the auto on the highways last weekend where the roads were intermittently clear. Honestly it's shocking how much worse Michigan is at clearing roads than New Hampshire was. But I guess that's why I buy 4x4s, it doesn't really matter. ;)

[bcazier]

The rear end may have locked up for traction. I notice mine is rough and jumps a little until the locker disengages.

 

 

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[fraggedout]

I'm 57 and have been driving 4WDs longer than I can remember and I've NEVER done anything (driving-related, that is) as stupid as what I did two days ago, now I'm worried sick that I've damaged my transfer case. Here's what happened:

 

I have a Sierra 2500 HD Diesel 4WD. Driving conditions were horrible on the interstate due to heavy rain. Maybe not quite trusting that my daytime running lights were actually working, I intended to reach down switch them over to the "on" position (not automatic). The knobs for the lights and 4WD controls are side-by-side and identical in a 2013 Sierra 4WD. Apparently I rotated the 4WD knob fully clockwise rather than the knob for the lights. I had just straightened out on the merge ramp when I did this and was already going nearly 60. I didn't notice any change in the handling, engine revs, noise, or anything of the type changes you would expect to hear. Not realizing my mistake, I then drove nearly 200 miles at freeway speeds (70-75 MPH). Again, I didn't notice ANY changes in the handling, noise, or revs. When I exited the interstate I turned into a nearby parking lot and it wasn't until I was easing into a tight parking spot that I noticed the grabbing sensation you typically notice when trying to turn sharply in 4WD-LO. I looked at the 4WD selector knob at this point and almost cried when I saw it was set on 4WD-LO. If you are an expert in this area, please answer this question: is it likely that I have done permanent damage to my transfer case? I'll read anyone's opinions, but I'm really asking for the opinion of someone who knows for sure. And here's what I'm also wondering since it didn't fly apart or make any strange noises: is GM smart enough to build in some sort of emergency override to prevent damage (i.e. running at 70 MPH in 4WD-LO) to the 4WD for folks like me who make this boneheaded mistake? If so, why weren't they smart enough to move the 4WD knob somewhere else and make it look different from the headlights knob? Thanks. EDIT: I just remember something...In my 2003 Silverado HD2500, you had to put the gear selector in Neutral before you could engage 4WD-LO. Since I was already moving forward in OD, could this have saved my a$$ and switched to 4WD-HI instead of LO?

[redwngr]

If you were running 75 and had 'normal' engine rpm, the is no way it went into 4-LO. (Get it into 4LO and drive it )

[darkfox1]

The knob based 4wd controls all go through the bcm/tcm and an "Encoder motor." If the vehicle was detecting you moving that fast when you made the switch, the knob was probably just flashing waiting on you to slow down to move the encoder over. It had probably been in 4-lo for just a few seconds.

 

If you had actually moved to 4lo you'd know it, AND you'd get a "service 4wd" notice in your dic if you broke an encoder motor.

 

More than likely you're fine.

 

I almost reached for my 4wd knob today when turning on my headlights. It poured rain all day here.

 

I drive in auto 4 when its raining heavy because I have some steep hills where I have to take off fast to keep from getting rearended by oncoming traffic. I've driven up to 74mph in auto 4 in the last several months.

 

I've only been in 4hi and 4lo once to make sure they work.

[Chad2815]

Mine got stuck in 4 lo once and I had to limp it to the dealer......it is impossible to go 70 mph in 4 lo. I was running 30 mph at 4000 rpm.

[Spurshot]

You'll be fine. The truck didn't go into 4 LO. It may have not even gone into 4wd at all. But more likely it went to 4 HI. Still, not something I'd worry about.

 

This stupid knob design was on my 2008 as well. I've made that mistake as well as others with that knob. If the bonehead ergonomics engineer that allowed that design with, twin identical knobs, side by side, and hidden behind the steering wheel to boot, to get out without an interlock didn't get fired, his boss should have been.