Electric Power Steering Control Unit, Component Description - GF46.35-S-7012A
Model 447
with code XM7 (MOPF II)
Electrical power steering (ES) control unit, shown on model 447.8
The numbers on the pins indicate the pin numbering of the slots.
Overview
This document contains information on:
- General
- Function
- Reading in of signals
- Evaluation of input factors
- Actuation of component parts
- Transmission of requests and information
- Ground connection
- Power supply
General
The electrical power steering (ES) control unit (N68) is mounted on the steering gear.
Function
The electrical power steering (ES) control unit (N68) is responsible for the following tasks:
- Reading in of signals
- Evaluation of input factors
- Actuation of component parts
- Transmission of requests and information
Reading in of signals
Direct line
The signal from the electric power steering torque sensor (N68b1) is read in via a direct line.
Suspension FlexRay (Flex E)
The following signals are read in via suspension FlexRay (Flex E):
- Wheel speeds and status of the brake from the Electronic Stability Program (ESP) control unit (N30/4)
- "Engine running" status, "Drivetrain operational" and engine speed from the powertrain control unit (N127)
- Ignition lock status, reverse gear status and status of on-board electrical system battery from electronic ignition lock (EZS) control unit (N73/8)
- Request for activation of dynamic movement of power limit of toothed rack from multifunction camera (MFK) control unit (B84/8) (with code EZ6 (Parking Package with 360° camera), code JB6 (Parking Package with 360° camera))
- Parking status from parking system control unit (N62/3) (with code EZ5 (Active Parking Assist with reversing camera), code EZ6 (Parking Package with 360° camera), code JB6 (Parking Package with 360° camera) or code JB7 (Parking Package with reversing camera))
- Steering wheel angle from the steering column tube module control unit (N80)
Evaluation of input factors
The read-in input factors are evaluated by the integrated microprocessor; the relevant component parts are then actuated and requests/information are output.
Actuation of component parts
The electric power steering actuator motor (N68m1) is controlled directly by the electrical power steering (ES) control unit (N68).
Transmission of requests and information
The request for a warning message to the instrument cluster (A1) or the instrument cluster control unit (N133/1) is sent via CAN 2 for the user interface (CAN HMI2) by the electronic ignition lock (EZS) control unit (N73/8). The electronic ignition lock (EZS) control unit (N73/8) receives the information via suspension FlexRay (Flex E) from the electrical power steering (ES) control unit (N68).
The following requests and information are output via suspension FlexRay (Flex E):
- Limit for front axle toothed rack force output, Steer Assist status, status of front axle wheel angle, current steering wheel torque and request for EPS indicator lamp to the Electronic Stability Program (ESP) control unit (N30/4)
- Status of front axle wheel angle to powertrain control unit (N127)
- Status of Steer Assist, status of front axle wheel angle, current steering wheel torque and request for EPS indicator lamp to the electronic ignition lock (EZS) control unit (N738)
- Limit for front axle toothed rack power output on wheel angle controller, status of hands-off detection, status of front axle wheel angle and fault status of electric power steering to the multifunction camera (MFK) control unit (B84/8) (with code EZ6 (Parking Package with 360° camera), code JB6 (Parking Package with 360° camera))
- Status of front axle wheel angle to the Active Brake Assist controller unit (B92) (with code BA3 (Active Brake Assist) or code ET4 (Active Distance Assist DISTRONIC))
- Status of front axle wheel angle and current steering wheel torque to the parking system control unit (N62/3) (with code EZ5 (Active Parking Assist with reversing camera), code EZ6 (Parking Package with 360° camera), code JB6 (Parking Package with 360° camera) or code JB7 (Parking Package with reversing camera))
The following input factors and initial parameters are read in or output over direct lines by the electrical power steering (ES) control unit (N68):
| Input factors over a direct line | Initial parameters over a direct line |
|---|---|
| Circuit 30t | - |
| Circuit 31 | - |
| Signal for electric power steering torque sensor (N68b1) | - |
Input factors and initial parameters for the following control units are sent or received by the electrical power steering (ES) control unit (N68) via suspension FlexRay (Flex E):
| Input factors and initial parameters via suspension FlexRay (Flex E) | Additional information |
|---|---|
| Multifunction camera (MFK) control unit (B84/8) | - |
| Active Brake Assist controller unit (B92) | With code BA3 (Active Brake Assist) |
| Active Distance Assist DISTRONIC electric controller unit (B92/1) | With code ET4 (Active Distance Assist DISTRONIC) |
| Electronic Stability Program (ESP) control unit (N30/4) | - |
| AIRMATIC control unit (N51/3) | With code CA4 (AIRMATIC) |
| Parking system control unit (N62/3) | With code EZ5 (Active Parking Assist with reversing camera) With code EZ6 (Parking Package with 360° camera) With code JB6 (Parking Package with 360° camera) With code JB7 (Parking Package with reversing camera) |
| Electronic ignition lock (EZS) control unit (N73/8) | - |
| Steering column tube module control unit (N80) | - |
| Powertrain control unit (N127) | - |
Ground connection
The "circuit 31" ground connection is provided on vehicles without code ZG2 (Permanent all-wheel drive/all-wheel drive 4MATIC) via ground point 2 at the front left (W9/7).
The "circuit 31" ground connection is provided on vehicles with code ZG2 (Permanent all-wheel drive/all-wheel drive 4MATIC) via the auxiliary battery ground point (W10/4).
Power supply
The power supply for "Circuit 30t" is implemented via the pre-fuse box (F1).