4 wheel drive "Auto" setting

Coppertone · January 10, 2016

I'd use auto a lot more if the screeching/buzzing sound wouldn't give me a headache.

SMiller · January 10, 2016

Are you actaully being serious? Ever rebuilt a transmission, differential, or t-case?

It is that kind of ignorant and irresponsible behavior that GM is as conservative with power reduction programming as they are. And people complain about it, well this is why.

Ever actually used a truck?

Ever been to a truck pull?

Ever seen a truck all twisted up and stuck?

I would much prefer to stress test something before owning it so I can rest assured I won't have issues.

'01LS1 · January 10, 2016

Figures.... I've been driving in auto mode for the past few days and I MUCH prefer it over the 2wd mode. It seems that the transmission is much more natural, fluid and responsive in auto mode. I don't find any of the transmission lag when in auto mode. In 2wd, the transmission seems to want to stay in the lower rpm range and needs more coaxing to get to the gear needed. In the auto mode, it is more aggressive in its gear choice and feels much more responsive. Also, I noticed that AFM seems to work more intelligently/smoothly in auto mode than 2wd mode. At least in terms of when it switched from 8 to 4 and back. I don't really have any good mpg indicators as traffic has been brutal the last few days.

I noticed the same thing today as well. My truck is a 2013 gmt 900, not the current K2xx but was interesting how much better it drove. Too note, snow was falling this afternoon & plows had not ran yet. So 2-3" of build up/slush & today was the first time ever using the auto. I could have made it around just fine in 2wd on the stock GY tires w/o issue. But was a good time to see what difference it made. Definitely liked the shift points better.

Why, because I am part of outage restoration for an electric utility company. No matter the weather I am required to come into work in order to help get the lights back on for people. Plus the fact that 4wd is only $2k more than 2wd and has better resale down the road is a win/win for me. My dad always told me the only truck worth owning is a 4wd truck, better to have and not need 4wd then to be stuck when you don't have it.

My Dad always told me a 4wd would get you 10' farther than the chain would reach. Though it was his way of saying he would rather not spend the extra money at purchase.

He always bought 2wd & my last three have been 4wd. More so for the just in case you need it & as you mentioned, resale.

BuyAmericanIron · January 10, 2016

Might as well stoke the fire

Recommendation/Instructions:

The apply plate bearing designs in these transfer cases are not rated for continuous operation. They are intended for intermittent operation only when 4WD is required.

Long periods of continuous operation have been experienced in the U.S northern border states and in the provinces of Canada. This type of operation will shorten the life of the transfer case and in particular the apply plate bearing. As a general rule transfer case selector switches should be left in the 2HI mode unless road conditions dictate otherwise.

The following is a guideline for the proper use of 4WD in Magna transfer cases RPO's NP1, NP8, NQH and NQF.

1. 2HI mode sends all of the drive train torque to the rear wheels. This provides the most fuel efficient driving mode.

2. Auto/4WD mode when engaged constantly monitors the vehicle's drivetrain to provide optimum traction as road conditions dictate. Torque is automatically transferred to the front wheels to provide seamless 4WD operation. Auto mode is intended for on-road driving that includes rain, snow, ice and gravel.

3. 4HI provides enhanced traction for snow, ice, and gravel and most off road conditions. It is not intended for use on dry pavement.

4. 4LO provides enhanced traction and increased torque multiplication to handle extreme on and off road conditions such as steep hills, deep sand, mud, snow and ice. 4LO can also be used during boat launch operations for increased torque availability.

Note: 2–4 Not intended for continuous operation.

NQH is the common transfer case used on these 14-16 K trucks. Among others.

Excellent explanation of how the "Auto" transfer case functions and it's proper use. That answered a few questions. Thanks!

Brian S. · January 10, 2016

Might as well stoke the fire

Recommendation/Instructions:

The apply plate bearing designs in these transfer cases are not rated for continuous operation. They are intended for intermittent operation only when 4WD is required.

Long periods of continuous operation have been experienced in the U.S northern border states and in the provinces of Canada. This type of operation will shorten the life of the transfer case and in particular the apply plate bearing. As a general rule transfer case selector switches should be left in the 2HI mode unless road conditions dictate otherwise.

The following is a guideline for the proper use of 4WD in Magna transfer cases RPO's NP1, NP8, NQH and NQF.

1. 2HI mode sends all of the drive train torque to the rear wheels. This provides the most fuel efficient driving mode.

2. Auto/4WD mode when engaged constantly monitors the vehicle's drivetrain to provide optimum traction as road conditions dictate. Torque is automatically transferred to the front wheels to provide seamless 4WD operation. Auto mode is intended for on-road driving that includes rain, snow, ice and gravel.

3. 4HI provides enhanced traction for snow, ice, and gravel and most off road conditions. It is not intended for use on dry pavement.

4. 4LO provides enhanced traction and increased torque multiplication to handle extreme on and off road conditions such as steep hills, deep sand, mud, snow and ice. 4LO can also be used during boat launch operations for increased torque availability.

Note: 2–4 Not intended for continuous operation.

NQH is the common transfer case used on these 14-16 K trucks. Among others.

Where did you get this?

I just looked in the owners manual for my 2015 Sierra and it only says to use the Auto 4wd when road conditions are variable, and only warns against using it to park on a slippery grade.

As such, I'd consider almost any use of it "variable conditions" outside of desert driving. We all get fair amounts of rain, some of us have snow on the roads half the year.

I plan to use it a good chunk of the winter, because it's not worth sliding off the road not to. (and you can't always see a slippery patch coming to shift into Auto 4)

If it "wears out" I'm asking for warranty repair, because I don't own them out of warranty.

bertiman · January 10, 2016

Where did you get this?

I just looked in the owners manual for my 2015 Sierra and it only says to use the Auto 4wd when road conditions are variable, and only warns against using it to park on a slippery grade.

As such, I'd consider almost any use of it "variable conditions" outside of desert driving. We all get fair amounts of rain, some of us have snow on the roads half the year.

I plan to use it a good chunk of the winter, because it's not worth sliding off the road not to. (and you can't always see a slippery patch coming to shift into Auto 4)

If it "wears out" I'm asking for warranty repair, because I don't own them out of warranty.

Tbarn, if you don't mind sharing, I was also wondering where this came from....

15 Z71 · January 10, 2016

I still don't understand why people use this in the rain. Was a rain snow mix today, roads wet. Absolutely no problems in 2wd. As a matter of fact, I could hardly spin unless I put it to the floor. But then again my truck came with bridge stone A/T's.

redwngr · January 10, 2016

I still don't understand why people use this in the rain. Was a rain snow mix today, roads wet. Absolutely no problems in 2wd. As a matter of fact, I could hardly spin unless I put it to the floor. But then again my truck came with bridge stone A/T's.

Traction control and stabilitrac also to reduce wheelspin and the back end from sliding out.

15 Z71 · January 10, 2016

That's my point, no need for auto in the rain.

tbarn · January 10, 2016

Tbarn, if you don't mind sharing, I was also wondering where this came from....

GM service information.

xelli · January 10, 2016

My Dad always told me a 4wd would get you 10' farther than the chain would reach.

Good Advice

xelli · January 10, 2016

Tbarn, if you don't mind sharing, I was also wondering where this came from....

GM service information.

And on page 9-45 of my owner's manual.

bertiman · January 10, 2016

And on page 9-45 of my owner's manual.

My owners manual does not say that... the only thing it warns against is parking on a hill in auto and that there will be slightly less fuel economy than 2wd.

bertiman · January 11, 2016

GM service information.

Thanks!

xelli · January 11, 2016

My owners manual does not say that... the only thing it warns against is parking on a hill in auto and that there will be slightly less fuel economy than 2wd.

Interesting. From my manual:

AUTO (Automatic Four-Week Drive): Use when road surface traction conditions are variable. When driving in AUTO, the front axle is engaged, and the vehicle's power is sent to the front and rear wheels automatically based on the driving connections. This setting provides sightly lower fuel economy than 2 (high).

Do not use AUTO mode to park on a steep grade with poor traciton such as ice, snow mud or gravel. In AUTO mode only the rear wheels will hold the vehicle from sliding when parked. If parking on a steep grade, use 4 (high) to keep all four wheels engaged.