Component Description Of Transfer Case Control Unit - GF28.19-D-3200TSB

Model 907 

with code ZG1 (Engageable all-wheel drive) 

Model 907 

with code ZG3 (Engageable all-wheel drive with gear reduction) 

Location 

The all-wheel drive control unit is located in the driver seat frame. Task 

The all-wheel drive control unit receives information from the following component parts over discrete lines:

• All-wheel drive activation button (S76/11), status on vehicles with code ZG1 (All-wheel drive, engageable) and on vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio)
• All-wheel drive reduction switch (S76/12), status on vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio)
• Transfer case absolute sensor (B57), actual position of selector drum
• Transfer case actuator motor (M46/2), turn rate and direction of rotation of transfer case actuator motor

The all-wheel drive control unit actuates the transfer case actuator motor over a discrete line by means of a pulse width modulated signal (PWM).

The all-wheel drive control unit receives information over the suspension FlexRay (Flex E) on the following component parts:

• Status of clutch pedal switch (S40/6)
• Status of Electronic Stability Program (ESP®)
• Status of brake light switch (S9/1)

The all-wheel drive control unit sends information over the suspension FlexRay (Flex E) to the following component parts:

• Instrument cluster (A1), status of transfer case, step-down ratio switched on or off, on vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio)
• ESP® control unit, status of transfer case, transmission ratio switched on or off, on vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio)
• ESP® control unit, status of transfer case, all-wheel drive switched on or off, on vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio) and on vehicles with code ZG1 (All-wheel drive, engageable)

If the transmission ratio is switched on and engaged in vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio), the LOW RANGE indicator lamp (A1 e37) is actuated in the instrument cluster.

If, on vehicles with code ZG3 (Engageable all-wheel drive with transmission ratio) or with code ZG1 (All-wheel drive, engageable), the all-wheel drive is switched on successfully in the all-wheel drive activation button (S76/11), an LED is illuminated to confirm that the all-wheel drive is activated.