SabrToothSqrl

Ok, so the 07+ Tahoe has 2WD, 4WD, and 'Auto' (and 4 low)

I understand 2, and 4, and low, but what does Auto do?

Please get as technical as possible

Does the transfer case have a diff in it too? or is it just a lock?

thanks!

Does it run in 4, with an open diff in the middle on auto or does it just 'detect' wheel slip in 2, and then engage 4 on its own?

73shark

This sounds like a setup after reading this:

https://chevroletforum.com/m_56360/tm.htm

SabrToothSqrl

No, no setup, I’m genuinely interested in how it works, I spend a lot of time on Wikipedia, howstuffworks.com, etc… I have a wrangler, and am very familiar with its setup, and my 95 Tahoe, but I don’t have a new Tahoe that I can just get under and check it all out, nor do I have a manual or FSM for it… on eBay I got the Jeep FSM as a PDF, I guess I could look up the Tahoe one…
My Tahoe disconnects the front axles at the diff via a vacuum system; and at the transfer case via a lever.
My Jeep just does it at the transfer case, the front spins all the time, including the driveshaft
My fiancé’s tribute uses a limited slip diff in the center that engages when the front end spins faster than the front, all auto (wuss control)
SO, I am just wondering what the new Tahoe does, also vs the AWD escalade, I assume that the Escalade has a center diff, but no transfer case, as it also has no 4-lo
Is 4-low in the Tahoe still 2.72 to 1?
I don’t plan on any 4-wheelin with the Tahoe (the jeep is for that) but it will tow the jeep to Rausch Creek… I plan on the 4WD for snow, as in PA, as in right now we have 3” on the ground…
Does the auto take the difference between the front and rear wheel speed sensors, then turn on 4WD? If so, when does it turn it back off?
The ‘auto’ on the Tribute can’t be disabled, which makes for NO fun in the snow… sometimes you want to slide in a parking lot for fun…
The Chevy web site doesn’t go into much detail on anything, the dodge one is bigger, so is the Toyota one (I am actually considering a 09 ram too lol)

73shark

Here's what I could find in the Owner's Manual:
You can choose among five driving settings:
Indicator lights in the switches show you which
setting you are in. The indicator lights will come on
briefly when you turn on the ignition and the last
chosen setting will stay on. If the lights do not
come on, you should take your vehicle in for
service. An indicator light will flash while shifting.
Fast flashing means the conditions were not
met to make the desired shift, typically the vehicle
was going too fast, the automatic transmission
was not in neutral, or the clutch pedal was not fully
pressed. Slow flashing means the shift is in
progress. It will stay on when the shift is
completed. If for some reason the transfer case
cannot make a requested shift, it will return to the
last chosen setting.
2 m (Two-Wheel Drive High): This setting is
used for driving in most street and highway
situations. Your front axle is not engaged in
two-wheel drive. This setting also provides the best
fuel economy.
AUTO (Automatic Four-Wheel Drive): This
setting is ideal for use when road surface traction
conditions are variable. When driving your
vehicle in AUTO, the front axle is engaged, but
the vehicle’s power is primarily sent to the
rear wheels. When the vehicle’s software
determines a need for more traction, the system
will transfer more power to the front wheels.
Driving in this mode results in slightly lower fuel
economy than Two-Wheel Drive High.
4 m (Four-Wheel Drive High): Use the
four-wheel high position when you need extra
traction, such as on snowy or icy roads or in most
off-road situations. This setting also engages
your front axle to help drive your vehicle. This is
the best setting to use when plowing snow.

4 n (Four-Wheel Drive Low): This setting also
engages your front axle and delivers extra
torque. You may never need this setting. It sends
maximum power to all four wheels. You might
choose Four-Wheel Drive Low if you are driving
off-road in deep sand, deep mud, deep snow, and
while climbing or descending steep hills.
StabiliTrak® will not engage in this mode. See
StabiliTrak® System on page 363 for more
information.
{CAUTION:
Shifting the transfer case to NEUTRAL
can cause your vehicle to roll even if the
transmission is in PARK (P). You or
someone else could be seriously injured.
Be sure to set the parking brake before
placing the transfer case in NEUTRAL.
See Parking Brake on page 156.
NEUTRAL (N): Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle. See
Recreational Vehicle Towing on page 418 or
Towing Your Vehicle on page 417 for more
information.
If the SERVICE 4 WHEEL DRIVE message stays
on, you should take your vehicle to your dealer
for service. See “SERVICE 4 WHEEL DRIVE
message” under DIC Warnings and Messages on
page 270.
Shifting Into Four-Wheel Drive High or
AUTO (Automatic Four-Wheel Drive)
Turn the **** to the Four-Wheel High or AUTO
position. This can be done at any speed,
except when shifting from Four-Wheel Drive Low.
The indicator light will flash while shifting. It will
remain on when the shift is completed.

Shifting Into Two-Wheel Drive High
Turn the **** to the Two-Wheel High position.
This can be done at any speed, except when
shifting from Four-Wheel Drive Low.
See shifting out of Four-Wheel Drive Low later in
this section for more information.
Shifting Into Four-Wheel Drive Low
When Four-Wheel Low is engaged, vehicle speed
should be kept below 45 mph. Extended
high-speed operation in 4L may damage or
shorten the life of the drivetrain.
To shift to the Four-Wheel Drive Low position, the
ignition must be in RUN and the vehicle must
be stopped or moving less than 3 mph (5 km/h)
with the transmission in NEUTRAL (N). The
preferred method for shifting into Four-Wheel Drive
Low is to have your vehicle moving 1 to 2 mph
(1.6 to 3.2 km/h). Turn the **** to the Four-Wheel
Drive Low position. You must wait for the
Four-Wheel Drive Low indicator light to stop
flashing and remain on before shifting your
transmission in gear.
Notice: Shifting the transmission into gear
before the Four-Wheel Drive Low indicator light
has stopped flashing could damage the
transfer case. To help avoid damaging your
vehicle, always wait for the Four-Wheel
Drive Low indicator light to stop flashing
before shifting the transmission into gear.
The vehicle may have significant engagement noise
and bump when shifting between Four-Wheel Drive
Low and Four-Wheel Drive High ranges or from
NEUTRAL while the engine is running.
If the **** is turned to the Four-Wheel Drive Low
position when your vehicle is in gear and/or
moving, the Four-Wheel Drive Low indicator light
will flash for 30 seconds and not complete the
shift unless your vehicle is moving less than 3 mph
(5 km/h) and the transmission is in NEUTRAL (N).
After 30 seconds the transfer case will shift to
Four-Wheel Drive High mode.

Shifting Out of Four-Wheel Drive Low
To shift from Four-Wheel Drive Low to Four-Wheel
Drive High, AUTO, or Two-Wheel Drive High, your
vehicle must be stopped or moving less than 3 mph
(5 km/h) with the transmission in NEUTRAL (N) and
the ignition in RUN. The preferred method for
shifting out of Four-Wheel Drive Low is to have your
vehicle moving 1 to 2 mph (1.6 to 3.2 km/h). Turn
the **** to the Four-Wheel Drive High, AUTO, or
Two-Wheel Drive High position. You must wait for
the Four-Wheel Drive High, AUTO, or Two-Wheel
Drive High indicator light to stop flashing and
remain on before shifting your transmission
into gear.
Notice: Shifting the transmission into gear
before the Four-Wheel Drive Low indicator light
has stopped flashing could damage the
transfer case. To help avoid damaging your
vehicle, always wait for the Four-Wheel
Drive Low indicator light to stop flashing
before shifting the transmission into gear.
The vehicle may have significant engagement
noise and bump when shifting between
Four-Wheel Drive Low and Four-Wheel Drive High
ranges or from NEUTRAL while the engine is
running.
If the **** is turned to the Four-Wheel Drive High,
AUTO, or Two-Wheel Drive High switch position
when your vehicle is in gear and/or moving,
the Four-Wheel Drive High, AUTO or Two-Wheel
Drive High indicator light will flash for 30 seconds
but will not complete the shift unless your
vehicle is moving less than 3 mph (5 km/h) and
the transmission is in NEUTRAL (N).
Shifting into NEUTRAL
To shift the transfer case to NEUTRAL do the
following:
1. Make sure the vehicle is parked so that it will
not roll.
2. Set the parking brake and apply the regular
brake pedal. See Parking Brake on page 156
for more information.
3. Start the vehicle or turn the ignition to RUN.
4. Put the transmission in NEUTRAL (N).
5. Shift the transfer case to Two-Wheel
Drive High.

6. Turn the transfer case dial clockwise to
NEUTRAL till it stops and hold it for
10 seconds. Then slowly release the dial to
the four low position. The NEUTRAL light will
come on when the transfer case shift to
NEUTRAL is complete.
7. If the engine is running, verify that the
transmission is in NEUTRAL (N) by shifting the
transmission to REVERSE (R) for one second,
then shift the transmission to DRIVE (D) for
one second.
8. Turn the ignition to ACCESSORY, which will
turn the engine off.
9. Place the transmission shift lever in PARK (P).
10. Release the parking brake prior to moving
the vehicle.
11. Turn the ignition to LOCK.
Shifting Out of NEUTRAL
To shift out of NEUTRAL do the following:
1. Set the parking brake and apply the regular
brake pedal.
2. Shift the transmission to NEUTRAL (N) and
turn the ignition to RUN with the engine off.
3. Turn the transfer case dial to the desired
transfer case shift position (Two-Wheel
Drive High, Four-Wheel Drive High, AUTO).
After the transfer case has shifted out of
NEUTRAL the NEUTRAL light will go out.
4. Release the parking brake prior to moving the
vehicle.
Notice: Shifting the transmission into gear
before the Four-Wheel Drive Low indicator light
has stopped flashing could damage the
transfer case. To help avoid damaging your
vehicle, always wait for the Four-Wheel
Drive Low indicator light to stop flashing
before shifting the transmission into gear.
5. Start the engine and shift the transmission to
the desired position.
Excessively shifting the transfer case into or out of
the different modes may cause the transfer
case to enter the shift protection mode. This will
protect the transfer case from possible damage
and will only allow the transfer case to respond to
one shift per 10 seconds. The transfer case
may stay in this mode for up to three minutes.

Hope this is helpful.

SabrToothSqrl

wow! thank you, i love reading this stuff, i hope you didn't have to type all that!

SabrToothSqrl

not very technical on HOW, but the info is still good, but it says 'clutch' I was unware of any 'stick' Tahoes... it says it sends more power to the rear in auto, but that the front axle is engaged... so that means it DOES have a center diff? or some clutch arraingment on the front axle engagement system... I could see that because it has to be stopped, then spin up before locking when going from 2WD to 4WD at speed.... "you may never need 4 low" lol, that's an understatement for this vehicle... does anyone here go 4-wheeling in their tahoes?

a vid

More videos

an 'automatic' transfer case doesn't usually cut it on the trail, find me an ATLAS II

I have a 95 Tahoe I would 'wheel when I get a new tahoe, but finding parts for it... no thanks...