Transfer case (VG), function

P27.19-2730-79

P28.00-2050-82

P28.10-2270-82

Transfer case (VG), general

Permanent all-wheel drive has advantages not only off-road but also on roads which provide good grip. Permanent all-wheel drive increases the number of driven wheels, thus improving tire-to-road adhesion. As a result, slip is reduced and the driving power is distributed to all of the wheels. The distributed driving power results in higher traction and higher lateral stability at the driven wheels. The standard equipment includes permanent all-wheel drive with three open differentials (transfer case, rear axle and front axle). The torque split of 50:50 %between the front axle and rear axle is specified as a fixed value in the transfer case. The gear ratio of the transfer case is 1:1. The driver can use the off-road package transmission mode control (with CODE 430 (On & Off-road package)) located on the lower control panel control unit to activate the off-road function (modified shift characteristic) in the automatic transmission. A changed accelerator pedal curve in the CDI control unit (with diesel engine) or ME-SFI [ME] control unit (with gasoline engine) and the off-road ABS function are additionally activated in the ESP® control unit. The driver can switch the downhill speed regulation on or off using the Downhill Speed Regulation button. The Downhill Speed Regulation button is also on the lower control panel control unit.

 MODEL 166 with TRANSMISSION 725.0
as of model year 2016
with CODE 430 (On & off-road package)
In vehicles with CODE 430 (On & Offroad package), the CODE 489 (AIRMATIC (air suspension with level adjustment and adaptive damping system ADS)) is automatically included.

P28.10-2269-82

With CODE 430 (On & Offroad package)

A permanent all-wheel drive with a lockable differential (transfer case) and two open differentials (front axle and rear axle) is used in the on & off-road package option. The torque split of 50:50 between the front and rear axle is specified as a fixed value in the transfer case for an open interaxle differential lock clutch pack. The "Low/High" function in the transfer case can be used to select two gear ratios. The on-road ratio "High" is 1:1, the off-road step-down ratio "Low" is 2.93:1. The transfer case is controlled by the transfer case control unit. The driver can switch between the "High" on-road ratio and the "Low" reduction ratio using the Low Range button which is in the lower control panel control unit. The differential lock in the transfer case can be actuated by the driver via the off-road package transmission mode control. The off-road package transmission mode controller provides 6 setting options and is located on the off-road operating panel control unit which is in the center console.

The following control units are involved in control of the transfer case:

 Transfer case control unit

 Offroad control panel control unit (with CODE 430 (On & Offroad package))

 Lower control panel control unit

 ME-SFI control unit (with gasoline engines)

 CDI control unit (with diesel engines)

 ESP® control unit

 Fully integrated transmission control unit

 AIRmatic control unit (with CODE 489 (AIRmatic (air suspension with level adjustment and adaptive damping system ADS)))

Further subfunctions are described in separate documents:

 Transfer case control, function (with CODE 430 (On & Offroad package))

 Downhill Speed Regulation, function

 Off-road transmission mode, function

 "Low/High" shift, function (with CODE 430 (On & Offroad package))

 Interaxle differential lock function (with CODE 430 (On & Offroad package))

 Transfer case oil supply, function