Steering Column Lock Control Unit, Basic Function - GF80.57-P-9891A

Model All (CAR) 

Fig 1: Steering Column Lock Control Unit Components Location - Model All (Car)

Courtesy of MERCEDES-BENZ USA

Example illustration of electrical steering column lock control unit 

Overview 

This document contains information on:

• General 
• Function requirements 
• Function 

General 

The electric steering column lock control unit determines the locking status of the steering column and activates unlocking or locking of the steering column.

Function requirements 

• Electronic ignition lock control unit active
• Ignition OFF (circuit 15C)
• Wheel pulse counter = 0

Function 

The electrical steering column lock control unit processes information from the electronic ignition lock control unit (EIS) and has two supply lines; one from the supplemental restraint system control unit (SRS) and another from the signal acquisition and actuation module respectively (SAM.

The electrical steering column lock control unit performs the following functions:

• Calculation of the hash value for checking the validity of the transmitter key.
• If the hash value is incorrect and the unlocking position is not reached or not detected, a fault message is sent to the electronic ignition lock control unit.
• Position monitoring of locking bolt via two switching contacts.
• Switching on integrated motor via the center-zero relay for locking and unlocking locking bolt.
• Arresting steering column with locking bolt.

The electrical steering column lock can only move the locking bolt in the lock direction if both supply lines are active. The electronic ignition lock control unit must request that the corresponding line is switched to active.