Component description for regenerative braking system control unit - GF42.22-P-1100FLM

MODEL 212.095/098/298 as of model year 2014 

Location 

The regenerative braking system control unit is on the traction system hydraulic unit at the left front inside the engine compartment.

View of engine compartment from above 

Fig 1: Regenerative Braking System Control Unit Components

Courtesy of MERCEDES-BENZ USA

Task 

The regenerative braking system control unit contains the control for the following systems:

• Regenerative braking system
• Electronic stability program (ESP)
• Electronic brake force distribution (EBV)
• Antilock brake system (AS)
• Acceleration Slip Regulation (ASR)
• Engine drag torque control (MSR)
• Brake Assist (BAS)
• Electronic Traction System (ETS)
• Tire pressure loss warning (RDW) (except code (475) Tire pressure monitor (Premium))
• HOLD (starting-off aid)
• Precharging dependent on accelerator pedal actuation (Ready Alert Braking) (RAB)
• Dry braking
• Passive ASR and ESP activation
• Adaptive brake lights, flashing (except code (494) USA version)
• PRE-SAFE
• Hill Start Assist (HSA)
• Fading brake support
• Air gap reduction (Airgap)
• Deceleration coordination of DISTRONIC PLUS (with code (233) Distronic Plus)
• Standstill coordinator (SSK)
• ESP trailer stabilization (Trailer Stability Assist (TSA) (with code (550) Trailer hitch)
• Variable speed limiter (except code (233) DISTRONIC PLUS, except code (494) USA version and except code (460) Canada version)
• CC (TPM) (except code (233) DISTRONIC PLUS and with code (440) CC)
• Automatic lane recognition (AFE) (with code (476) Automatic Lane Recognition)

For vehicles with code (233) DISTRONIC PLUS, the variable speed limiter and the cruise control are integrated into the radar sensors control unit (N62/1).

The regenerative braking system control unit has the following tasks:

• Reading in of sensors, pickups and signals
• Evaluation of input factors
• Requesting regenerative braking torque

CAN data bus 

The regenerative braking system control unit is connected to the CAN network of the vehicle over chassis CAN 1 (CAN E1) and the vehicle dynamics CAN (CAN H).

CAN network

The regenerative braking system control unit exchanges data with other control units integrated in the CAN network, via the connected chassis CAN 1 and the vehicle dynamics CAN (CAN H).

Input and output signals 

The regenerative braking system control unit reads in and evaluates input signals and outputs the corresponding output signals via the following connections:

• Direct line 
• Chassis CAN 1 
• Vehicle dynamics CAN 

Direct line (input signals) 

• Circuit 30
• Circuit 87
• Circuit 31
• BAS membrane travel sensor (A7/7b1)
• Vacuum sensor (A7/7b3)
• Pedal angle sensor (B37/1)
• Brake light switch (S9/1)
• Vacuum pump relay (+) (K109)
• Brake pressure simulator valve pressure sensor (B18/5)
• Left front axle RPM sensor (L6/1)
• Right front axle RPM sensor (L6/2)
• Left rear axle RPM sensor (L6/3)
• Right rear axle RPM sensor (L6/4)

Direct line (output signals) 

• Brake light actuation through rear SAM control unit with fuse and relay module (N10/2)
• Traction system hydraulic unit (A7/3)
• Brake pressure simulator valve (Y113)
• Vacuum pump relay (+) (K109)
• Vacuum pump relay (-) (K109/1)
• Power supply for yaw rate sensor for lateral and longitudinal acceleration (B24/15)
• Power supply for BAS membrane travel sensor (A7/7b1)
• Power supply for BAS solenoid valve (A7/7y1)
• Power supply for pedal angle sensor (B37/1)
• Power supply for brake pressure simulator valve pressure sensor (B18/5)
• Power supply for brake vacuum sensor (B64/1)
• Brake light switch power supply (S9/1)

The following listing, for example represents the most important control units and components through which CAN messages are exchanged over the CAN network.

Chassis CAN 1 

• CDI control unit (N3/9) (for diesel engine) or ME-SFI [ME] control unit (N3/10) (for gasoline engine)
• Front SAM control unit with fuse and relay module (N10/1)
• Steering column tube module control unit (N80)
• Fully integrated transmission control unit (Y3/8n4)
• Instrument cluster (A1)
• Rear SAM control unit with fuse and relay module (N10/2)
• Supplemental restraint system control unit, component description (N2/10)
• Radar sensors control unit (N62/1) (with code (23P) Driving assistance package)

Vehicle dynamics CAN 

• Yaw rate sensor for lateral and longitudinal acceleration (B24/15)