Rear Control Unit, Component Description - GF54.21-P-4134GR

MODEL 166 up to model year 2016 

Shows model 166.0 

Fig 1: Rear Control Unit Component Location - Model 166 Up To Model Year 2016

Courtesy of MERCEDES-BENZ USA

Task 

The rear control unit supplies various systems and control units with voltage via limit switches depending on the function sequence.

The rear control unit also has the following tasks:

• Reading in of sensors and signals 

Location 

The rear control unit is located in the center under the rear bench seat.

• Evaluation of input factors 
• Controlling functions 
• Actuation of components 

Reading in of sensors and signals 

The input factors are read in via the following connections:

• Direct line 
• Interior CAN (CAN B) 

Direct line 

The signals from the following components are read via direct lines:

• Left 2nd seat row release unit (A93/3) (with CODE 843 (EASY-ENTRY electric))
• Right 2nd seat row release unit (A93/4) (with CODE 843 (EASY-ENTRY electric))
• Left pop-out window anti-pinch protection contact strip (B51/5) (Model 166.8)
• Right pop-out window anti-pinch protection contact strip (B51/6) (Model 166.8)
• Liftgate rotary tumbler switch (M14/7s1)
• Liftgate locking pawl switch (M14/7s2)
• Rear camera cover motor switch (M35/2s1) (model 166.8 with CODE 501 (360-degree camera))
• Left 3rd seat row folding backrest motor (M53/10) (Hall sensor) (model 166.8)
• Right 3rd seat row folding backrest motor (M53/11) (Hall sensor) (model 166.8)
• Left 2nd seat row head restraint motor (M53/12) (Hall sensor) (with CODE 843 (EASY-ENTRY electric))
• Center 2nd seat row head restraint motor (M53/13) (Hall sensor) (with CODE 843 (EASY-ENTRY electric))
• Right 2nd seat row head restraint motor (M53/14) (Hall sensor) (with CODE 843 (EASY-ENTRY electric))
• Right rear brake wear sensor (S10/4)
• Liftgate control button (S62/36) (with CODE 890 (EASY-PACK liftgate))
• Left rear seat belt buckle switch (S68/5)
• Right rear seat belt buckle switch (S68/6)
• Center rear seat belt buckle switch (S68/14)
• Left 3rd seat row seat belt buckle switch (S68/16) (model 166.8)
• Right 3rd seat row seat belt buckle switch (S68/17) (model 166.8)
• Liftgate contact switch (S88/6)
• Left 3rd seat row folding backrest switch (load compartment) (S158/5) (model 166.8)
• Left 3rd seat row folding backrest switch (2nd seat row at left) (S158/6) (model 166.8)
• Left 3rd seat row folding backrest switch (2nd seat row at right) (S158/7) (model 166.8)
• Right 3rd seat row folding backrest switch (load compartment) (S158/8) (model 166.8)
• Right 3rd seat row folding backrest switch (2nd seat row at left) (S158/9) (model 166.8)
• Right 3rd seat row folding backrest switch (2nd seat row at right) (S158/10) (model 166.8)
• Right 2nd seat row easy entry/exit switch (S159/1) (model 166.8)
• Left 2nd seat row easy entry/exit switch (S159/2) (model 166.8)
• Left 2nd seat row folding backrest switch (S162/1) (with CODE 843 (EASY-ENTRY electric))
• Right 2nd seat row folding backrest switch (S162/2) (with CODE 843 (EASY-ENTRY electric))

Interior CAN 

The signals are read in by the rear control unit over the interior CAN.

The functions that use these signals are described in the individual function descriptions (see appropriate block diagram or function schematic).

Evaluation of input factors 

The input factors are evaluated by the microprocessor and the corresponding components are actuated.

Controlling functions 

The rear control unit actuates the following functions:

• Instrument panel ambiance illumination (with CODE 876 (Interior lights package))
• Liftgate central locking and power closing
• Seat heater in rear (with CODE 872 (Electrically heated left and right rear seats))
• Opening and closing of pop-out windows (on model 166.8)
• Opening and closing of rear camera cover (on model 166.8 with CODE 501 (360-degree camera))

Actuation of components 

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

• Direct line 
• Interior CAN 
• Left pop-out window motor (M21/8) (model 166.8)
• Right pop-out window motor (M21/9) (model 166.8)
• Rear camera cover motor (M35/2) (with CODE 218 (Reversing camera) or CODE 501 (360-degree camera))

Direct line 

The following components are actuated via direct lines:

• Left 3rd seat row backrest release unit (A93/1) (model 166.8)
• Right 3rd seat row backrest release unit (A93/2) (model 166.8)
• Left front illuminated door sill molding (E17/47) (with CODE 876 (Interior lights package))
• Right front illuminated door sill molding (E17/48) (with CODE 876 (Interior lights package))
• Liftgate ambient lamp (E40)
• Driver-side instrument panel ambiance illumination (E43/7) (with CODE 876 (Interior lights package))
• Passenger-side instrument panel ambiance illumination (E43/8) (with CODE 876 (Interior lights package))
• Liftgate central locking motor (M14/7)
• Liftgate lock element (M14/31)
• Left 3rd seat row folding backrest motor (model 166.8)
• Right 3rd seat row folding backrest motor (model 166.8)
• Left 2nd seat row head restraint motor (with CODE 843 (EASY-ENTRY electric))
• Center 2nd seat row head restraint motor (with CODE 843 (EASY-ENTRY electric))
• Right 2nd seat row head restraint motor (with CODE 843 (EASY-ENTRY electric))
• Left rear seat cushion heater pad (R13/5) (with CODE 872 (Electrically heated left and right rear seats))
• Left rear backrest heater pad (R13/6) (with CODE 872 (Electrically heated left and right rear seats))
• Right rear seat cushion heater pad (R13/7) (with CODE 872 (Electrically heated left and right rear seats))
• Right rear backrest heater pad (R13/8) (with CODE 872 (Electrically heated left and right rear seats))

Interior CAN 

The signals are sent over the interior CAN by the rear control unit. The functions that use these signals are described in the individual function descriptions (see appropriate block diagram or function schematic).