GF28.19-P-3200VG Component Description of Transfer Case Control Unit

GF28.19-P-3200VG Component description of transfer case control unit
- with engine 156, 272, 273, 642 [model 164.1]
- with engine 273, 642 [model 164.8]
- Transmission 722.9
- with CODE (430) Offroad package

Component Identification:

Location
The transfer case control unit is located in the front passenger footwell.

Task

General
The transfer case control unit monitors and shifts the transfer case according to:
- Vehicle speed
- Selector lever in position "N"
- "Low Range" switch (N72s31) actuated
- Position of transfer case actuator motor (M46/2)

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
- Antilock brake 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 data bus
The transfer case control unit is connected to the CAN system of the vehicle via the engine compartment CAN (CAN-C).

Input and output signals
The following input signals are evaluated by the transfer case control unit and the corresponding output signals are issued:
^ Direct input signals
^ Direct output signals
^ CAN input signals
^ CAN output signals

Direct input signals
- Circuit 15
- Circuit 30
- Circuit 31
- Actuator motor rotation direction sensor
- Actuator motor speed sensor
- Actuator motor temperature
- Transfer case absolute sensor (B57)

Direct output signals
- Sensor supply voltage (5V)
- Sensor ground
- Transfer case actuator motor
- Transfer case switchover magnet (Y108)

CAN input signals
Instrument cluster (A1)
- Status of displayed speed

Intelligent servo module for DIRECT SELECT (A80)
- Position of range selector lever

CDI control unit (N3/9) or ME-SFI [ME] control unit (N3/10)
- Engine speed
- Engine torque
- Pedal value

Rear axle differential lock control unit (N15/9)
- Actual value of rear differential lock

AIRmatic control unit (N51)
- Vehicle level status

Steering column tube module (N80)
- Steering wheel angle status
- Left multifunction steering wheel button group signal (S110)
- Right multifunction steering wheel button group signal (S111)

ESP control unit (N47-5)
- ABS request
- ESP requirement
- DSR LED (Downhill Speed Regulation) ON/OFF

Fully integrated transmission control unit (VGS) (Y3/8n4)
- Actual/target gear

Central gateway control unit (N93)
- Low Range ON/OFF
- Specified value of differential locks
- Diagnosis request

CAN output signals
Instrument cluster (A1)
- Transfer case status for multifunction display (A1p13)

CDI control unit (N3/9) or ME-SFI control unit (N3/10)
- Transfer case status

Rear axle differential lock control unit (N15/9)
- Specified locking torque

ESP control unit (N47-5)
- Transfer case status
- DSR variable speed limiter ON/OFF actuated
- Actual value of differential locks
- Specified locking torque

Central gateway control unit (N93)
- Actual value of differential locks
- Transfer case LED status
- Diagnostic data

Fully integrated transmission control unit (VGS) (Y3/8n4)
- Transfer case status
- Status, shift to "N"