4x4 - Auto mode - Learn me ....

[mitchntx]

I understand how stability control works ... sensors feed a computer and braking is applied as and where needed.

 

So when I'm in 4WD "Auto" mode, power is applied to the front instead of rear brakes or in addition to rear brakes?

[waumo1]

From my 2011 owner's manual -

 

"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, but the vehicle's power is sent only 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."

 

I assume the percent power sent to the front wheels is variable like our Jeep SRT but it doesn't specifically state that.

[kstruckcountry]

To my knowledge Auto doesn't affect braking. If you're referring to the computer applying front brakes for traction, I think the behavior is the same as 4hi. I could be wrong though.

 

Auto uses I think what's called a viscous clutch. With "X" difference between front and rear driveshafts the pressure kicks it in and sends power to the front. My understanding is that it isn't variable, it's either engaged or it isn't.

[mitchntx]

It appears I did a lousy job of asking the question ...

 

When in 2WD and the vehicle loses traction, rear brake is applied to help stabilize the vehicle.

 

When in 4WD "Auto" is it clutching in front drive only or a combination of front drive AND rear brake?

 

Traction control and stability control has gotten pretty damed sophisticated.

[waumo1]

How about this from the manual -

 

"If the vehicle has StabiliTrak®,
shifting into Four-Wheel Drive
Low will turn Traction Control and
StabiliTrak off. See StabiliTrak®
System on page 9‑70."

 

Which would seem to indicate that both are active in all other modes (unless you turn Stabilitrak off with the switch).

[aflesch]

This is from Alldata:

 

"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 the
wheel speed sensors. When 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 2/4 wheel drive actuator assembly. This actuator rotates the
transfer case control actuator shaft, applying a clutch. The clutch 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 wheel speed sensors matches that
of the rear speed sensors. Torque is ramped down to the front wheels.
The process would repeat if rear wheel slip is detected again."

[kstruckcountry]

Which would seem to indicate that both are active in all other modes (unless you turn Stabilitrak off with the switch).

I think this is what the OP is after.

[mitchntx]

Thanks for the replies, fellers and yes I would like to know if in "Auto" I have power being applied to the front, while dragging the rear.

 

Sounds like if I want to cut a good 60', "Auto" is the feature to have. But plowing through snow or mud, 4Hi is best so that the driver has control over momentum.