4x4 Auto ?

morrislee · October 24, 2015

I have always been suspicious about electronics that are labeled "Auto", can someone explain to me what the Auto under 4x4 knob in my 2014 1500 GMC Sierra is really doing?

Is it "auto" as in variable power distributed between 4 wheels based on tire traction? Like AWD? 4x4 under low speed and switches back to 2wd above a certain speed? This is not very clear in the user manual, how does it know when to switch to 4x4 is the real core information needed, "based on driving conditions" is not very clear to me.

AUTO (Automatic Four-Wheel Drive): This setting is ideal for use when road surface traction conditions are variable. When driving the vehicle in AUTO, the front axle is engaged, and the vehicle's power is sent to the front and rear wheels automatically based on driving conditions. Driving in this mode results in slightly lower fuel economy than Two-Wheel Drive High.

Also, when it is in 4x4, how much power is distributed to the front? How much to the back? or is it 50/50 on these trucks?

If there is somewhere I can find thee information, great, because I do not know what key words to look for....Sorry!!

Z45 · October 24, 2015

Hope this helps.....

AUTOMATIC TRANSFER CASES
The last category is a combination of 4WD and On Demand AWD. These transfer cases have a 2HI, Auto-4WD, 4HI, 4LO and Neutral position and would fall in the general 4WD category. This transfer case has the operating characteristics of both an On Demand AWD and a Part-Time 4WD system depending on the mode selected. This transfer case uses a clutch pack to allow for a difference in speed between the front and rear axles in the Auto-4WD mode. In the 4HI or 4LO modes, there is no allowance for the difference in speed between the front and rear axles.

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If the transfer case is operated in 4HI or 4LO, it will behave as a Part-Time 4WD system. If it is operated in the Auto 4WD mode, it will behave like an on-demand AWD system.
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The second category is an on-demand AWD. This type of AWD basically delivers torque only to a primary driving axle unless reduced traction is experienced. At that point, the system electronically or mechanically will apply torque to the other axle. Depending on the type of system, this can provide up to 100% of the torque to the axle with traction. These transfer cases use an electronically actuated clutch pack, a hydraulically actuated clutch pack, or a viscous coupling to allow for a difference in speed between the front and rear axles.

waumo1 · October 24, 2015

On my 2011, Auto 4WD works very well. Best I can determine, it works much like our Jeep SRT. A small amount of power is going to the front (maybe 5%) and as needed more power is shifted to the front via the transfer case clutch packs. Slippage of the clutches allows steering without the lockup of full 4WD mode.

Our 2002 Yukon had Auto 4WD but it was terrible.

Doug_Scott · October 25, 2015

From what I am reading here, the auto 4x4 behaves just like the traditional posi-trac differential works. Puts a tight clutch pack between front and rear differentials, and the clutch pack will slip once there is enough "pressure" difference between front and rear axle. On a traditional 4x4 system in 4 wheel drive on dry pavement, the chassis will actually start to twist up until something gives, usually one end of the truck will slip the tires on the pavement eventually.

A viscous coupler behaves very much like a torque converter, when one side of the coupler begins to spin faster than the other side, the oil between them will drive the slower spinning side. Like two fans, facing each other, with oil between them instead of air, the spinning oil will drive the slower fan until speed matches. They could even set these up to lock up electrically when auto is moved to 4x4. Most AWD systems use a viscous coupler.

kstruckcountry · October 25, 2015

The NVG 246 EAU provides 5 modes, Auto 4WD, 4HI, 4LO, 2HI and Neutral. The Auto 4WD position allows the capability of an active transfer case, which provides the benefits of on-demand torque biasing wet clutch and easy vehicle tuning through software calibrations. The software calibrations allow more features such as flexible adapt ready position and clutch preload torque levels. The technology allows for vehicle speed dependent clutch torque levels to enhance the performance of the system. For example, the system is calibrated to provide 0-5 ft lb of clutch torque during low speed, low engine torque operation, and predetermined higher torque for 40 km/h (25 mph) and greater. This prevents crow-hop and binding at low speeds and provides higher torque biases at higher vehicle speeds, in order to enhance stability. The NVG 246 EAU transfer case features a 4 button shift control switch located on the instrument panel. When the ignition key is in the RUN position, the transfer case shift control module monitors the transfer case shift control switch to determine if the driver desires a new mode/range position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/range position. The lamp will continue to flash until all shifting criteria has been met and the new mode/range position has been reached, or has been engaged. Once the new mode/range position is fully active, the switch indicator lamp for the new position will remain ON constantly. During normal driving situations, the transfer case can operate in the Auto 4WD mode. In the Auto 4WD mode, the transfer case shift control module monitors rear wheel slip speed, based on the inputs from both the front and rear propshaft speed sensors. When the vehicle experiences a rear wheel slip condition, the vehicle experiences a rear wheel slip condition, the transfer case shift control module sends a pulse width modulated (PWM) signal to an electronic motor, which is the transfer case encoder motor. This motor rotates the transfer case control actuator lever shaft, applying a clutch pack. This clutch pack is designed to deliver a variable amount of torque, normally delivered to the rear wheels, and transfers it to the front wheels. Torque is ramped up to the front wheels until the front propshaft speed sensor matches that of the rear propshaft speed sensor. Torque is ramped down to the front wheels. The process would repeat if rear wheel slip is detected again. The NVG 246 EAU transfer case has the added feature of also providing the driver with 3 manual mode/range positions:

*4HI - 4 Wheel Drive high range

*2HI - 2 Wheel Drive high range

*4LO - 4 Wheel Drive low range.

morrislee · October 25, 2015

Hope this helps.....

Interesting, where did you find this info?

On my 2011, Auto 4WD works very well. Best I can determine, it works much like our Jeep SRT. A small amount of power is going to the front (maybe 5%) and as needed more power is shifted to the front via the transfer case clutch packs. Slippage of the clutches allows steering without the lockup of full 4WD mode.

Our 2002 Yukon had Auto 4WD but it was terrible.

I think GM had a different design in that year range 2002.

From what I am reading here, the auto 4x4 behaves just like the traditional posi-trac differential works. Puts a tight clutch pack between front and rear differentials, and the clutch pack will slip once there is enough "pressure" difference between front and rear axle. On a traditional 4x4 system in 4 wheel drive on dry pavement, the chassis will actually start to twist up until something gives, usually one end of the truck will slip the tires on the pavement eventually.

A viscous coupler behaves very much like a torque converter, when one side of the coupler begins to spin faster than the other side, the oil between them will drive the slower spinning side. Like two fans, facing each other, with oil between them instead of air, the spinning oil will drive the slower fan until speed matches. They could even set these up to lock up electrically when auto is moved to 4x4. Most AWD systems use a viscous coupler.

LOL, I don't even know what posi-trac means, I am learning here, this is good!!!! viscous coupler technology is familiar to me, we have it in GM trucks? Viscous couple, does that have to do with wet clutch kstruckcountry is referring to?

The NVG 246 EAU provides 5 modes, Auto 4WD, 4HI, 4LO, 2HI and Neutral. The Auto 4WD position allows the capability of an active transfer case, which provides the benefits of on-demand torque biasing wet clutch and easy vehicle tuning through software calibrations. The software calibrations allow more features such as flexible adapt ready position and clutch preload torque levels. The technology allows for vehicle speed dependent clutch torque levels to enhance the performance of the system. For example, the system is calibrated to provide 0-5 ft lb of clutch torque during low speed, low engine torque operation, and predetermined higher torque for 40 km/h (25 mph) and greater. This prevents crow-hop and binding at low speeds and provides higher torque biases at higher vehicle speeds, in order to enhance stability. The NVG 246 EAU transfer case features a 4 button shift control switch located on the instrument panel. When the ignition key is in the RUN position, the transfer case shift control module monitors the transfer case shift control switch to determine if the driver desires a new mode/range position. At a single press of the transfer case shift control switch, the lamp of the new desired position will begin flashing to inform the driver that the transfer case shift control module has received the request for a new mode/range position. The lamp will continue to flash until all shifting criteria has been met and the new mode/range position has been reached, or has been engaged. Once the new mode/range position is fully active, the switch indicator lamp for the new position will remain ON constantly. During normal driving situations, the transfer case can operate in the Auto 4WD mode. In the Auto 4WD mode, the transfer case shift control module monitors rear wheel slip speed, based on the inputs from both the front and rear propshaft speed sensors. When the vehicle experiences a rear wheel slip condition, the vehicle experiences a rear wheel slip condition, the transfer case shift control module sends a pulse width modulated (PWM) signal to an electronic motor, which is the transfer case encoder motor. This motor rotates the transfer case control actuator lever shaft, applying a clutch pack. This clutch pack is designed to deliver a variable amount of torque, normally delivered to the rear wheels, and transfers it to the front wheels. Torque is ramped up to the front wheels until the front propshaft speed sensor matches that of the rear propshaft speed sensor. Torque is ramped down to the front wheels. The process would repeat if rear wheel slip is detected again. The NVG 246 EAU transfer case has the added feature of also providing the driver with 3 manual mode/range positions:

*4HI - 4 Wheel Drive high range

*2HI - 2 Wheel Drive high range

*4LO - 4 Wheel Drive low range.

Thank you for the in-depth explanation, this gives me more confidence using the Auto mode when the winter comes. last winter, I have been using 4x4 when I am on slippery ice or thick snow, I didnt trust the Auto mode at all.

Am I right to assume the 4x4 system in our truck (4x4 Hi in particular) locks up 4 wheels (all 3 clutches are fully engaged)? If this is the case, what happens to the automatic rear locking diff?

Another thing I have noticed on the 3/4 ton 2014 sierras at work with 6.0L motor, they do not have the Auto option but there is 4 Hi and 4 Low, are they still using a different transfer case?

Thanks guys, you have all been very helpful!!

Z45 · October 25, 2015

I don't even know what posi-trac means

Positraction is a old Chevrolet sales name used to denote their limited slip differentials which are normally installed in cars. Actually they have not used that term since the 60's and 70's muscle car era.

Note - G80 is used to denote either a limited slip or a locking differential.

Am I right to assume the 4x4 system in our truck (4x4 Hi in particular) locks up 4 wheels (all 3 clutches are fully engaged)? If this is the case, what happens to the automatic rear locking diff?

No. G80 Auto Locking differential engages when one of the rear wheels senses a difference in 100 rpm and then it will lock up. But if will release once traction is normalized between the left and right rear wheel or 20 mph. In reality all you have a 3 wheel drive, the front axle does not lock up. If they did if would be extremely difficult to steer and turn. Front is a open differential.

Z45 · October 25, 2015

Interesting, where did you find this info?

An information bulletin from GM

The purpose of this bulletin is to help explain the operating characteristics of 4WD/AWD systems.

For specific operating instructions for individual transfer cases, please refer to the Owner Manual or Service Information.

DEFINITIONS

AWD vs. 4WD

The very basic difference between AWD and 4WD is the intended usage of the systems.

AWD is usually intended for on-road use in inclement weather conditions, while operating smoothly on dry pavement by allowing for a difference in speed between the front and rear axles while turning. These systems are not selectable and do not have low range gearing for the transfer case. These systems can be found in cars or trucks.

4WD is primarily found in trucks and can be broken down into Part-Time, Full-Time, and Automatic Transfer Cases. These selectable systems have modes intended for on-road use and other modes intended for off-road or low traction situation usage. All current GM 4WD systems have a low range available in the transfer case.

CHARACTERISTICS

Disclaimer: Even though a certain amount of noise or feel can be expected, GM may offer service procedures or components, or change vehicle design, which may reduce perceived noise levels in the interest of customer satisfaction.

AWD

There are two different categories of AWD systems. The first category is full-time AWD. This type of transfer case delivers torque to the front and rear axles at all times. This ratio can vary depending on the system, but is usually about a 30/70% front to rear split but also can vary depending on traction conditions, up to 100% front or rear. This type of transfer case can have a viscous coupling for low traction conditions along with a planetary gear set to allow for difference in speeds between the front and rear axle, or an open type of planetary gear set differential, which uses brake based traction control for low traction conditions. An example of a vehicle with an open differential/traction control type of transfer case is a 2003 Escalade. RPO codes for these types of transfer cases are NP3 (NVG 149, BW 4473 viscous clutch) and NR3 (BW 4476, 4481, 4485, open differential) or NR4/NR6 (BW 4493, 4494 open differential).

The second category is an on-demand AWD. This type of AWD basically delivers torque only to a primary driving axle unless reduced traction is experienced. At that point, the system electronically or mechanically will apply torque to the other axle. Depending on the type of system, this can provide up to 100% of the torque to the axle with traction. These transfer cases use an electronically actuated clutch pack, a hydraulically actuated clutch pack, or a viscous coupling to allow for a difference in speed between the front and rear axles. An example of an electronically controlled version of the On-Demand AWD is in the Smart Trak system in the 2003 Bravada. An example of a hydraulically operated On-Demand AWD is the Versa Trak system in the Aztek, while a viscous coupling is used in the Vibe. The RPO code for the Bravada is NP4 (NVG126). For some vehicle lines, there is not an RPO code. The only way to tell is by the Line Chassis VIN code, B for the Rendezvous/Aztek, V for the Venture/Montana or by SM for the Vibe.

PART-TIME 4WD

Part time 4WD refers to vehicles equipped with a transfer case to split power between the front and rear axles of the vehicle. This traditionally is a 2-speed selectable transfer case that can be shifted into 2HI, 4HI, 4LO and usually a Neutral position. The 4WD modes of Part time systems do not allow for a difference in speed between the front and rear axles while turning. This system effectively locks the front and rear propeller shafts together. When turning, the tires must allow for the different turning radius of the front and rear axles, which is why this is intended for low traction or off-road use. These systems have low range gearing for the transfer case. An example of a vehicle with this style of transfer case would be a Silverado with a manual shift transfer case (a shift lever on the floor) (RPO NP2) or a Colorado with a push button transfer case with a 2HI, 4HI, 4LO and Neutral position (RPO NP1). The RPO codes for this style of transfer case are NP1 (NVG 233, 243, 263, and T-150 push button) or NP2 (NVG 231, 241,261, BW 4401, 4470 shift lever).

FULL-TIME 4WD

A second version of a 4WD transfer case is a full-time 4WD transfer case. This style of transfer case has an open center differential to allow for different speeds between the front and rear axles and operates similar to an AWD system. This transfer case can be locked to operate like a Part-Time 4WD transfer case (no difference between front and rear prop-shaft speeds) and/or uses a traction control system to assist in low traction situations. These transfer cases also have a selectable low range. An example of this type of 4WD is the H2. RPO code is NR4.

The NR4 transfer case (available in non-luxury utilities) has no switch selection to lock into a part-time 4WD mode as described above. There are only 3 selections on the controls: Disable Stabilitrak, AWD and 4LO. The Owner's Manual describes this system as an AWD system.

AUTOMATIC TRANSFER CASES

The last category is a combination of 4WD and On Demand AWD. These transfer cases have a 2HI, Auto-4WD, 4HI, 4LO and Neutral position and would fall in the general 4WD category. This transfer case has the operating characteristics of both an On Demand AWD and a Part-Time 4WD system depending on the mode selected. This transfer case uses a clutch pack to allow for a difference in speed between the front and rear axles in the Auto-4WD mode. In the 4HI or 4LO modes, there is no allowance for the difference in speed between the front and rear axles. An example of a vehicle with this would be a Sierra with a push-button transfer case with a 2HI, Auto-4WD, 4HI, 4LO, and Neutral positions. The RPO code for these transfer cases is NP8 (NVG 226, 236, 246, 246 EAU).

DIAGNOSTIC AIDS

Always follow Strategy Based diagnostics and service information in Service Information (SI). SI is constantly updated with new and more thorough information.

One of the first steps that can be used in determining if a noise is a characteristic is to compare it to a similar vehicle. The comparison vehicle should be as close to the original vehicle as possible, including mileage, GVW, RPO, chassis style (extended cab, short-bed...).

Attempts to correct characteristic types of noise and/or feel should not be performed. In most situations, these conditions will not be changed. Any attempts to correct these conditions may reduce customer confidence and inconvenience the customer while their vehicle is out of service.

4WD

While operating 4WD vehicles in the 2HI mode, they should perform similarly to an equivalent 2WD version of the vehicle. However there are still additional components on the vehicles and there may still be some slight differences in characteristics. Some Part-Time 4WD transfer cases may make a slight gear rattle type of noise when operated in 2HI at low engine speeds, similar to a manual transmission gear rattle type of noise. This can originate in the synchronizer assembly from engine harmonics. This noise will usually be reduced or eliminated while driving in a 4WD mode because the synchronizer assembly clearances will be taken up once engaged in 4WD. Operating the engine at a slightly higher rpm should reduce this noise.

While a vehicle is traveling down the road, the tires rotate a certain number of times per mile depending on the true tire radius. If all the tires do not have the exact same true radius (due to load, tire pressure, wear, build variances...), they will turn at slightly different rates. Also, unless the vehicle is traveling in a perfectly straight line, the front and rear axles are traveling in a slightly different arc, which means the front and rear axles are traveling at slightly different average speeds.

These systems either do not have a center differential or it has been bypassed (when used in 4HI or 4LO in Part-Time or Automatic systems, or 4HI Lock or 4LO Lock on Full-time 4WD), so the front and the rear propeller shafts will turn at the same speed, which leads to the front, and rear axles rotating at the same average speed. Using the 4WD modes (4HI, 4LO, 4HI Lock, 4LO Lock) will usually increase noise in the axles, transfer case and the rest of the driveline and is usually greater at higher speeds and will usually increase the more the vehicle is turned. As the vehicle turns, the front and rear axles follow a different arc. When this occurs, the only place to compensate for this binding is between the contact patch of the tires and the ground. This can feel like the vehicle is vibrating, crow hopping or grabbing. Even if the vehicle is driven in a straight line, there are slight differences in tire circumference that will cause some driveline binding. If a vehicle had the exact same size tires and was driven in a perfectly straight line, the fact that more parts are moving would mean that there would be more noise and possibly some feel of the system operating.

Use of 4HI or 4LO and 4HI Lock or 4LO Lock on Full-time 4WD is intended for use on a low traction surface such as snow, ice, mud or sand. On a low traction surface, the differences in front and rear axle speeds will not have as much effect on binding because of the lower traction levels between the surface and the contact patch of the tires. On a high traction surface, the higher traction levels will create more binding and noise in the driveline.

As a result, a small amount of noise or feel of the system operating can be expected when using 4HI or 4LO in Part-Time or Automatic systems, or 4HI Lock or 4LO Lock on Full-time 4WD. The noise and feel can vary depending on the transfer case type, GVW ratings (generally the higher the GVW the more noise it will make), vehicle build variations, gear ratios in the axles, axle type, tires, and importantly driving conditions.

While the transfer case is in Neutral, with the engine running, some noise can be expected.

When transfer case is shifted to 4LO (or any time through or from neutral, for example from 2HI to 4LO or back) with the engine running, or with the vehicle moving, some grinding noise can be expected. In some vehicles you may experience a slight bump as the shift to 4LO is completed. This occurs because the 4LO range is not synchronized and there may be a difference in transfer case input shaft and output shaft speeds, especially if the vehicle is moving or equipped with an automatic transmission (residual torque from the transmission may be driving the transfer case input shaft). To minimize this noise the shift may be completed at a stop and in an engine off, key on mode. However, there may be an increased chance of having a blocked shift (some models must have the engine restarted to complete the shift). Noise and bump levels will vary between vehicles and even between shifts on the same vehicle. As a reminder, if attempting to determine if noise or bump experienced in one vehicle is a characteristic, be sure to compare to similar make vehicles. For example the shift to 4LO in a Colorado or Canyon will usually have more noise and/or bump feel than in a Silverado or Sierra. When driving in 4LO, the extra gear reduction will make additional noise compared to driving in 4HI. The automatic transmission shift characteristics will also feel different while operating in 4LO.

AWD

AWD systems are intended for use in high and low traction situations without operator input. These systems will generally be quieter on high traction surfaces than a similar 4WD used in 4HI or 4LO. However, these systems will generally make more noise than a similar 2WD vehicle simply because there are more parts rotating and more gear sets interfacing. Once again, these systems may make more noise in turns, and in some situations you may be able to feel the system operating, even on high traction surfaces. Additionally, you may feel transfer case operation in on-demand AWD systems. These systems generally react to a speed difference between the front and rear axle and it may be possible to detect this by hearing a noise, or actually feeling the engagement of the system.

Automatic Transfer Cases

Automatic transfer cases will have the characteristics of both the Part-Time 4WD and the AWD systems depending on the mode selected. If the transfer case is operated in 4HI or 4LO, it will behave as a Part-Time 4WD system. If it is operated in the Auto 4WD mode, it will behave like an on-demand AWD system.

Driveline noises in 4WD or AWD vehicles caused by loading may be mistaken for transfer case or front axle noise because they can sound very similar. Four-wheel drive noises caused by loading may exhibit the following conditions:

• The noise will be greatest on a clear, dry road and decrease on a low traction surface. Front axle or transfer case noise caused by bearings, ring and pinion, or planetary gearing will be similar on all surfaces.

• The noises or feel that can be expected will increase while making a tight turn.

• The noises may be changed from a deceleration to an acceleration condition (or acceleration to deceleration) by raising or lowering tire pressure at one end of the vehicle.

TIRES

Tire rolling rates can be a major factor in operational characteristics. Consider the following important items:

• All tires are the same size and brand. Tires of different brands may have different circumferences (or radius) even if they are the same size.

• Tires are set to factory recommended pressures. A tire with low air pressure will roll at a different rate.

• All tires have approximately equal amounts of wear. Tires with different amounts of wear will roll at different rates.

• All tires are the same tread type. Don't mix on-off road, all-season or street tires on the same truck as they may have different circumferences and roll at different rates.

• One or more of the tires may show small, short scratches around the circumference of the tire tread. The tire "scuffing" on the road surface causes these scra

Z45 · October 25, 2015

fyi.............

¨ Optional Equipment (G80 Order Code) on all GM two-wheel and four-wheel drive light trucks and sport utilities.

Benefits

¨ Improved traction differentiates the vehicle relative to other rear wheel and four-wheel drive vehicles on the market.

¨ Maintenance free; requires no lube additives.

¨ Enhanced towing and off-road performance.

¨ Patented carbon friction disc technology enhances performance and durability while reducing warranty claims.

Principles of Operation

¨ Wheel speed difference (left to right) in excess of 100 RPM will cause a flyweight mechanism to open and catch a latching bracket.

¨ The stopped flyweight will trigger a self-energizing clutch system, which results in the cam plate ramping against a side gear.

¨ Ramping increases until both axles turn at the same speed (full lock), which prevents further wheel slip.

¨ At speeds above 20MPH, the latching bracket swings away from the governor and prevents lockup from occurring.

Technical Specifications

¨ Automatic locking takes place within a fraction of a second, so smoothly that it is unnoticed by the average driver.

¨ Unlocking occurs automatically, once the need for improved traction is gone, and is unnoticeable to the average driver.

¨ Compatible with anti-lock brake systems.

morrislee · October 25, 2015

Positraction is a old Chevrolet sales name used to denote their limited slip differentials which are normally installed in cars. Actually they have not used that term since the 60's and 70's muscle car era.

Note - G80 is used to denote either a limited slip or a locking differential.

No. G80 Auto Locking differential engages when one of the rear wheels senses a difference in 100 rpm and then it will lock up. But if will release once traction is normalized between the left and right rear wheel or 20 mph. In reality all you have a 3 wheel drive, the front axle does not lock up. If they did if would be extremely difficult to steer and turn. Front is a open differential.

I have tried to turn in 4x4, it is harder than in 2 Hi, do you mean true 4x4 will be even harder to turn?

kstruckcountry · October 25, 2015

I have tried to turn in 4x4, it is harder than in 2 Hi, do you mean true 4x4 will be even harder to turn?

Yes, it'll be even harder. Try to avoid using 4hi on "high traction" surfaces like dry pavement.

kstruckcountry · October 25, 2015

On my 2011, Auto 4WD works very well. Best I can determine, it works much like our Jeep SRT. A small amount of power is going to the front (maybe 5%) and as needed more power is shifted to the front via the transfer case clutch packs. Slippage of the clutches allows steering without the lockup of full 4WD mode.

Our 2002 Yukon had Auto 4WD but it was terrible.

The system in the 2002 and 2011 are basically identical I believe. Very similar function (if it's working right).

morrislee · October 25, 2015

Yes, it'll be even harder. Try to avoid using 4hi on "high traction" surfaces like dry pavement.

Lol, yes, of course

waumo1 · October 25, 2015

The system in the 2002 and 2011 are basically identical I believe. Very similar function (if it's working right).

The auto 4wd in the 2002 must have not been working correctly then because it seemed to be in/out rather than than proportional control. The operation of the 2002 Auto 4WD was one of the reasons I hesitated buying the Jeep but after I drove one at the Track Experience that concern was gone.

Z45 · October 25, 2015

Auto 4x4 is on demand, it is in 2wd and and when the rear wheels start slipping, TC locks up and engages the front axle. Once traction is equalized, the TC unlocks the front axle and goes back into 2wd mode.

I drive all winter in AUTO, unless I am driving on completely bare roads, which is infrequent in my locale. Lake Superior dumps a lot of snow on this part of Upper Michigan.