9,865 miles 4Wd services just come up

[Tylus]

I driven plenty gooder in snow in times of past gone

I completely agree this issue resolved needs be

I don't agree that you should deliberately continue to operate Auto 4wd when it will break knows you. Me driven have plenty times from Seattle to Austin and back in Dead of Winter through Wyoming/Montana/Utah/Colorado with 4-5ft of snow on the roads and in night of dead. Only rarely needs I the 4x4.



in all seriousness, you guys are placing too much faith in a 4x4 setup to keep your vehicle on the road. In all actuallity, the 4x4 is more likely to put your car in the ditch.

It's the same principle as driving your car with a posi vs. open rear diff on slippery stuff (ie: ice/snow/heavy rain)

with the posi, both tires spin and you lose traction quite easily. this lets the rear of the car drift side to side and a loss of control.

with the open diff, only 1 tire spins. so even if it loses traction, the other rear tire maintains the vehicle planted in respsect to side to side motion.​

now apply that to the front axle. with Auto 4wd the system is kicking in/out as the system sees need. this means your front wheels could be pulling and causing a loss of that lateral stability as you'll go from 2 of 4 tires with traction that maintain sideways stability to potentially 0 of 4 tires. try it sometime on dirt and you'll see what I mean.

I can do a wicked burnout on dirt and drift my 4x4 truck like it's a hot rod with the rear end sliding everywhere (posi rear).

If it were a open diff, the one tire fire keeps me going (slowly but surely) in a straight line because the other rear tire maintains side to side.​

when I'm in 4x4 and punch it, the V-10 has been known to launch me into a sideways drift with the whole rig because I'll have 3 of 4 tires yanking and it's easy to overcome the 4th tires stiction. I've done it on the pavement before and that is a scary


I don't like AWD rigs for the same reason I don't like Auto 4wd. It creates a false sense of confidence that a driver should never have in crappy road conditions. This leads to those idiots driving 70+ mph in the snow/ice and/or Soccer moms driving down slippery streets at speeds that are only safe on dry pavement.





sorry for the thread derail. I really do hope y'all get the t-case issue fixed. I'm slowly becoming a GM convert. I wouldn't mind adding a 2014/2015 Silvy Quad Cab to the stable in a few years once they get cheaper.

 

[HAARubicon]

I'm confused by this thread

You know your T-case has a programming issue. And yet...you continue to use Auto 4WD. Why?

It eats more gas
It causes more wear and tear
It has a known problem that GM is trying to fix

Mind boggling to me. My wife and I survived for many moons without Auto 4x4. Whenever she needed the 4x4, she leaned over and flipped the lever/rotated the knob to 4x4. Then drove until not needed anymore. Then flipped it back into 4x2


I think you guys are placing way to much faith in a system. That leads to a false sense of security and empowerment. This leads to driving beyond your capabilites on the road. Which in turn leads to accidents and mistakes.

Auto 4x4 is a crutch you shouldn't utilize. It'll only get your into worse situations. I totally get the "keep the family safe" attitude. My wife hauls around my 4 rugrats all the time also (hence the 2015 model for her). But I'd rather she drive to the conditions vs. placing her faith in a mechanical system to enhance.


hope GM fixes the t-case issue for you guys

You need to understand the principle of Auto 4wd. On a nice pretty day, when the pavement is dry the vehicle is basically in 2wd while set to Auto4wd. There is no bad gas mileage, there is no excessive wear and tear on components because it is running in 2wd. Now, a rain storm pops up, and you take off from a red light, the tires begin to slip. At that point Auto4wd kicks in to provide additional traction to prevent fish tailing or sliding. Once traction is reestablished the system "Automatically" (thus the term Auto) goes back to 2wd mode. This system is intended to be on all the time. I chose to run mine 2wd because I am old school, but that is me.

This system does not utilize axle lockers, so even in 4wd you are not getting traction at all 4 corners. Both front and rear are limited slip, the rear has posi. Its only bad if your "punching" it in a bad traction situation, at that point you are not using common sense and driving irresponsibly and no system can fix stupid. GM has utilized the Auto4wd system for over ten years now starting in the GMT 800 platform, I don't think there has been a single accident attributed to its use.

Auto4wd is a 2wd setting 98% of the time, and 4wd is only activated when the system tells it to. In a $70k, the system should work regardless if you chose to utilize it or not.

Mine was delivered set in the Auto4wd setting because that is the way the system is intended to run, it is not an All Wheel Drive system, if you want that buy a Subaru, that All Wheel drive system is phenomenal and my daughter loves it in her Forester XT.

---------- Post added at 09:28 AM ---------- Previous post was at 09:13 AM ----------

Plus, the problem is not just limited to Auto4wd, the same thing happens if you engage 4wd because you need it. If you leave it set and turn it off, it wont go back to Auto or 2wd.

GM, please fix it.

 

[07Burb]

If GM intended people to run in Auto 4WD all the time why is there a traction control system? Wouldn't the traction control system then be rendered redundant and unnecessary? This is why I've NEVER needed 4wd of any kind in rain or "light snow" (3 inches or less) because the traction control system is more than adequate to handle these conditions.

the same thing happens if you engage 4wd because you need it. If you leave it set and turn it off, it wont go back to Auto or 2wd.

GM, please fix it.

....now this I agree is the root of the problem

 

[HAARubicon]

If GM intended people to run in Auto 4WD all the time why is there a traction control system? Wouldn't the traction control system then be rendered redundant and unnecessary? This is why I've NEVER needed 4wd of any kind in rain or "light snow" (3 inches or less) because the traction control system is more than adequate to handle these conditions.



....now this I agree is the root of the problem

That is a good question, and be honest I think it was originally that way. I believe Auto4wd was introduced way back when if you bought a 4wd you did not get traction control and this made up for it. Traction control was only available in the 2wd models and used the braking system to try to maintain control.

It has become a little system crazy to be honest with you.

I may need to check, but I think Traction control is disabled while in Auto4wd and enabled if you set it to 2wd, which would make sense.

 

[07Burb]

That is a good question, and be honest I think it was originally that way. I believe Auto4wd was introduced way back when if you bought a 4wd you did not get traction control and this made up for it. Traction control was only available in the 2wd models and used the braking system to try to maintain control.

It has become a little system crazy to be honest with you.

I may need to check, but I think Traction control is disabled while in Auto4wd and enabled if you set it to 2wd, which would make sense.

Yeah that'd be interesting to know because you'd think the two would fight for control so to speak I know that when my kids ask me to do donuts in the snow I can manually turn off the traction control system (which brings up a warning that I've done so) but I've never paid attention to if that same thing occurs in Auto which I use very sparingly anyway. I'm like you and don't like to count on a system to help me choose what I'm driving it so I use the knob to be in 4 hi, 4 lo or 2wd so that I have that control so I've never used Auto 4wd in any of my vehicles for this reason

 

[HAARubicon]

Yeah that'd be interesting to know because you'd think the two would fight for control so to speak I know that when my kids ask me to do donuts in the snow I can manually turn off the traction control system (which brings up a warning that I've done so) but I've never paid attention to if that same thing occurs in Auto which I use very sparingly anyway. I'm like you and don't like to count on a system to help me choose what I'm driving it so I use the knob to be in 4 hi, 4 lo or 2wd so that I have that control so I've never used Auto 4wd in any of my vehicles for this reason

You and I agree about control and run in 2wd for that very reason. However, for those who want to run in Auto4wd, they should be able to do so without getting a system error.
And once GM gets a fix for this, they should also be able to run in Auto4wd knowing that it has no adverse affects on the vehicle long term in either excessive wear and tear or gas mileage because the system truly is a real fancy 2wd mode.

 

[Tylus]

How does the system engage 4wd on demand?

Is it doing via the t-case or the hubs?

If via the t-case, then you guys realize the entire front drivetrain is rotating at vehicle speeds 100% of the time right. So you're "dragging" that rotational mass around all the time. Hence lower mpg and performance hit the Owners Manual talks about. It's relatively easy to sync the t-case with trans input as needed at speeds. Just need a really quick shifting solenoid to swap between 2 and 4 mode

Now if they are doing it via the hubs...well that'd be just stupid. I don't even know how'd they'd be able to sync the hub to the wheel. In a split second the system would go from zero to highway speed and have to mate perfectly without destroying itself. Variations of this exist, but typically the t-case engages first to bring everything to speed, then the hubs engage seamlessly


I understand very much how this supposed Auto 4wd works. I think the inverse is true for some of y'all. Hopefully someone can confirm, but I'm pretty sure the Auto4wd is a fancy Constant Velocity setup like Dodge/Jeep (ie: hubs always engaged) use and the electronic nannies just engage the t-case as needed.

 

[humer101]

How does the system engage 4wd on demand?

Is it doing via the t-case or the hubs?

If via the t-case, then you guys realize the entire front drivetrain is rotating at vehicle speeds 100% of the time right. So you're "dragging" that rotational mass around all the time. Hence lower mpg and performance hit the Owners Manual talks about. It's relatively easy to sync the t-case with trans input as needed at speeds. Just need a really quick shifting solenoid to swap between 2 and 4 mode

Now if they are doing it via the hubs...well that'd be just stupid. I don't even know how'd they'd be able to sync the hub to the wheel. In a split second the system would go from zero to highway speed and have to mate perfectly without destroying itself. Variations of this exist, but typically the t-case engages first to bring everything to speed, then the hubs engage seamlessly


I understand very much how this supposed Auto 4wd works. I think the inverse is true for some of y'all. Hopefully someone can confirm, but I'm pretty sure the Auto4wd is a fancy Constant Velocity setup like Dodge/Jeep (ie: hubs always engaged) use and the electronic nannies just engage the t-case as needed.

Is not that much different I when to Williamsburg Virginia this weekend and was 17.8 round trip. 4wd
Las time the same location was 18.5 2wd almost 800 miles twice.

 

[HAARubicon]

How does the system engage 4wd on demand?

Is it doing via the t-case or the hubs?

If via the t-case, then you guys realize the entire front drivetrain is rotating at vehicle speeds 100% of the time right. So you're "dragging" that rotational mass around all the time. Hence lower mpg and performance hit the Owners Manual talks about. It's relatively easy to sync the t-case with trans input as needed at speeds. Just need a really quick shifting solenoid to swap between 2 and 4 mode

Now if they are doing it via the hubs...well that'd be just stupid. I don't even know how'd they'd be able to sync the hub to the wheel. In a split second the system would go from zero to highway speed and have to mate perfectly without destroying itself. Variations of this exist, but typically the t-case engages first to bring everything to speed, then the hubs engage seamlessly


I understand very much how this supposed Auto 4wd works. I think the inverse is true for some of y'all. Hopefully someone can confirm, but I'm pretty sure the Auto4wd is a fancy Constant Velocity setup like Dodge/Jeep (ie: hubs always engaged) use and the electronic nannies just engage the t-case as needed.

Running in Auto is very much like the Old Jeep Grand Wagoneers of the 80's up to 91 (accept for the auto tcase engagement). In order to get better gas mileage we would change the front hubs to selectable warn hubs so we could switch to free wheeling front hubs so the front axle and drive shaft were not spinning causing parasitic loss in the drivetrain. My 89 Grand Wag has been running in the factory configuration for 25 years now without selectable hubs. (driving it today btw) Before then they were quadratrac, all wheel drive system, back in the late 70's and early 80's, My 78 Cherokee runs AWD and has for 36 years.

Anyway, I am going to continue to run mine in 2wd, select Auto when conditions are variable, select 4wdhi when conditions demand it and probably never engage 4lo because if the terrain demands that I will probably be ripping off the stupidly low front air dam.

 

[humer101]

It come up again,this is getting bad now,I don't use long time and today was raining hard and I have to meet a customer in very difficult area. I use and boom, service 4wd.