4 wheel auto how it works .

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Woodblocker55

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Mine if I have it on .. at first little orange light is on I drive for a while and orange light gots out ..this is the orange light on the 4wheel auto button .

Next question what speed can you drive at in 4wheel auto .

This is 2006 Yukon XL with 2 speed transfer case high and low 4x4 . 4:10 gears .

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swathdiver

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Transfer Case - NVG 246-NPS (Two Speed Automatic)

Transfer Case General Operation

The New Venture Gear model NVG 246 RPO NP8 transfer case is a two speed automatic, active, transfer
case. 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 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

The driver may choose to select any of these mode/range positions while driving the vehicle. However,
the transfer case will not allow a shift into or out of 4LO unless the following criteria has been met:

• The engine is running.
• The automatic transmission is in Neutral.
• The vehicle speed is below 5 km/h (3 mph).

This transfer case also has a Neutral position. A shift to the Neutral position allows the vehicle to be
towed without rotating the transmission output shaft. Neutral position may be obtained only if the following
criteria has been met:

• The engine is running.
• The automatic transmission is in Neutral.
• The vehicle speed is below 5 km/h (3 mph).
• The transfer case is in 2HI mode.

Once these conditions have been met, press and hold both the 2HI and 4LO buttons for 10 seconds.
When the system completes the shift to neutral, the red neutral lamp will illuminate.

The NVG 246 EAU case halves are high-pressure die-cast magnesium. Ball bearings support the input
shaft, the front output shaft, and the rear output shaft. A thrust bearing is located inside of the input shaft
gear to support the front of the rear output shaft. The transfer case requires Auto Trac® II Fluid
GM P/N 12378508 (Canadian P/N 10953626) which is blue in color. The fluid is designed for smooth
clutch application. An oil pump, driven by the rear output shaft, pumps the fluid through the rear output
shaft oil gallery to the clutch and bearings.

There are two versions of the NVG 246 EAU, which depend on the transmission applications and vehicle
applications. If the vehicle is equipped with a transmission RPO M30, the transmission splines in the input
gear will have 27 teeth. With this application the planetary carrier assembly will have 3 pinion gears. If the
vehicle is equipped with transmission RPO MT1 or MN8, the transmission splines in the input gear will
have 32 teeth. The planetary carrier assembly on this application will have 6 pinion gears.


You drive as fast as you want in 4Auto. Limit 4LO to about 35-40 MPH as 4-5,000 rpms is the critical speed of the driveshafts.
 
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Woodblocker55

Woodblocker55

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Priceless info thanks . I'm printing it . One day I will reseat the connector on 4x4 button module my lights all have issues because the white lights don't work all the time either I might be better off just buy that whole button cluster. I seen there under $50 what's the best brand to get ? Dorman? [emoji106][emoji6]

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Fless

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TRW made many of the dash switches and that name is molded to the back of the switch. You can get one from U-Pull and ohm the modes to be sure (I can point you to values if you wish). From the factory the mode lights are LED, and the backlighting is incandescent. It also doesn't hurt to reflow the solder on the pins that are on the back of the switch. The newer lead-free (or low-lead) solder that's used on those can get brittle and make for intermittent connections.

The mode LEDs are not white, IIRC, unless they've been changed.
 

mijohnst

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Junkyard. I see those switches all over the place.
 

Fless

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rjr

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Swathdiver: Thank you much. For a long time I hsave been looking for a description of how the GMC transfer case actually works.

It is much smoother than the one I had on a 1997 Expedition, which you could feel engage when rear wheels slipped. Never felt that on my 2007 Yukon or my current 2015. The 2015 has the single speed transfer case. Do you happen to know what model number that would be and whether it works te same as you described above?
 

swathdiver

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Swathdiver: Thank you much. For a long time I hsave been looking for a description of how the GMC transfer case actually works.

It is much smoother than the one I had on a 1997 Expedition, which you could feel engage when rear wheels slipped. Never felt that on my 2007 Yukon or my current 2015. The 2015 has the single speed transfer case. Do you happen to know what model number that would be and whether it works te same as you described above?

Hi Bob, the single speed is the MP3010, RPO NP0. Operation is essentially the same.

https://gearsmagazine.com/magazine/magnas-mp-3010-transfer-case/
 

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