Component Description Of Transfer Case Control Unit - GF28.19-P-3200VGF

MODEL 166 with TRANSMISSION 725.0 as of model year 2016 with CODE 430 (On & off-road package) 

View of vehicle from left, shown on model 166.0 

Location 

The transfer case control unit is under the front passenger seat.

Task 

General 

The transfer case control unit monitors and shifts the transfer case according to:

• Vehicle speed
• Selector lever in position "N"
• Low Range button (N72s31) actuated
• Position of off-road package transmission mode control (N72/3s1)
• Position of transfer case actuator motor (M46/2)
• Wheel speeds

The following control functions are performed by the transfer case control unit:

• Pre-control of the locking torque
• Slip-dependent lock control/slip control
• Lock actuation when braking
• Anti-lock braking system (ABS) control
• Electronic Stability Program (ESP®) control
• Lock overload protection

The following basic functions are performed by the transfer case control unit:

• Computation of engine torque
• Computation of vehicle reference speed
• Cornering recognition
• Tire tolerance detection
• Flash programming
• Diagnosis
• Caster
• Variant coding
• Calibration run

CAN bus 

The transfer case control unit is connected to the CAN system of the vehicle through the drive train CAN (CAN-C).

Input and output signals 

The transfer case control unit evaluates the following input signals and issues the corresponding output signals:

• Direct input signals 
• Direct output signals 
• CAN input signals 
• CAN output signals 
• Transfer case actuator motor
• Transfer case switchover magnet (Y108)

CAN input signals 

Instrument cluster (A1) 

• Status of displayed vehicle speed

CDI control unit (N3/9) (with diesel engine) or ME-SFI [ME] control unit (N3/10) (with gasoline engine) 

• Engine speed
• Engine torque
• Accelerator pedal value

AIRmatic control unit (N51/3) (with CODE 489 (AIRmatic (air suspension with level adjustment and adaptive damping system ADS))) 

• Vehicle level status

Steering column tube module control unit (N80) 

• Steering wheel angle status
• Left multifunction steering wheel button group signal (S110)
• Right multifunction steering wheel button group signal (S111)

Electronic Stability Program control unit (N30/4) 

• ABS request
• ESP® request
• DSR status (D  ownhill S  peed R  egulation) ON/OFF
• Wheel rotational speed and direction of rotation

Fully integrated transmission control unit (Y3/8n4) 

• Actual/target gear
• Transmission mode request

Electronic ignition lock control unit (N73) 

• Drive authorization system (DAS) enable

SAM control unit (N10) 

• Low Range ON/OFF
• Specified value of differential locks
• Diagnosis request

Trailer recognition control unit (N28/1) (for CODE 550 (Trailer hitch)) 

• Trailer recognition signal

CAN output signals 

Instrument cluster 

• Status of transfer case for multifunction display (A1p13)

CDI control unit (for diesel engine) or ME-SFI [ME] control unit (for gasoline engine) 

• Transfer case status

Direct input signals 

• Terminal 15
• Terminal 30
• Circuit 31
• Transfer case actuator motor rotation direction sensor
• Transfer case actuator motor speed sensor
• Transfer case actuator motor temperature
• Transfer case absolute sensor (B57)

Direct output signals 

• Sensor supply voltage (5 V)
• Circuit 31 sensor

ESP® control unit 

• Transfer case status
• DSR variable speed limiter ON/OFF actuated
• Differential lock status
• Specified locking torque

SAM control unit 

• Differential lock status
• Status of transfer case LED on off-road control panel control unit (with CODE 430 (On & off-road package)) or in off-road program button (N72s38) (with CODE 489 (AIRmatic (air suspension with level adjustment and adaptive damping system, ADS)))
• Diagnostic data

Fully integrated transmission control unit 

• Transfer case status
• Status, shift to "N"