Rear control unit, component description - GF54.21-P-4134LA

MODEL 216.3 as of Model Year 09 /Modification year 08

Location

The rear control unit is underneath the right armrest in the rear.

Fig 1: Identifying Rear Control Unit

Courtesy of MERCEDES-BENZ USA

Task

The rear control unit has the following tasks:

Reading in of sensors, pickups and signals
Evaluation of input factors
Actuation of components

Reading in of sensors, pickups and signals

The input factors are read in with the following connections:

Direct line
Interior CAN

Direct line

The following sensors and switches are read in via a direct line:

Hall sensor of left rear power window motor (M10/5)
Hall sensor of right rear power window motor (M10/6)
Left rear power window switch (S21/3)
Right rear power window switch (S21/4)

Interior CAN

Signals from the following components are read in via the interior CAN:

by the EZS control unit (N73)

Tml. 15
Status of central locking

from left door control unit (N69/1):

Child protection switch for rear side windows (S20/1s5)
Driver power window outside mirror and trunk lid switch group (S20/1)

from front SAM control unit with fuse and relay module (N10/1):

Day/night changeover

Evaluation of input factors

The input factors that have been read in are evaluated by the integrated microprocessor and the relevant components are then actuated.

To protect the power window motors the rear control unit calculates the temperature at the bearing points of the power window motors from the respective operating period, operating voltage, rpm of the power window motors as well as the outside temperature and inside temperature. When a certain threshold temperature is reached the corresponding power window motor is still only actuated until the request is discontinued or until an end position is reached.

Subsequent operation of the power window motor affected is only possible again after a cooling down phase calculated by the rear control unit.

Actuation of components

The actuation of the components takes place via the following connections:

Direct line
Interior CAN

Direct line

The following components are actuated via a direct line:

Left rear power window motor (M10/5)
Right rear power window motor (M10/6)
Locator lighting in the power window switches (circuit 58d)
Left head restraint raise valve (Y24/4)
Right head restraint raise valve (Y24/5)

Interior CAN

The signals are transmitted by the rear control unit via the interior CAN.

The resultant functions are described in the respective function descriptions (see block diagram or function schematic).

Thermal protection for rear power window motors:

To protect the rear power window motors the rear control unit calculates the temperature at the bearing points of the respective rear power window motor from the operating period, operating voltage, rotational speed of the respective rear power window motor as well as the outside and inside temperature.

When a certain threshold temperature is reached the rear power window motor is still only actuated until the request is discontinued or until an end position is reached.

With an automatic run-up a reversing of the movement direction is still made possible after triggering the overload protection limiting.

Further operation of the rear power window motor is only possible again after a cooling down phase calculated by the rear control unit.

Wiring diagram rear control unit

PE67.39-P-2101-99CAA