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Home >> BMW >> 2018 >> X3 M40i >> Repair and Diagnosis >> External Pages >> Different car >> Section 763 (Functional Descriptions - F25 - Charging System, Anti-Theft, Body Electrical Systems) >> Body Electrical System - Functional Description >> Parking brake (electromechanical parking brake = EMF) >> System functions >> Roll monitoring

Roll monitoring

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The roll monitoring function is intended to prevent the vehicle rolling away when the parking brake is engaged. Roll monitoring is always activated if the state of the parking brake changes from released to engaged and ends following a defined time period after this state change.

A signal from the DSC is used to detect any rolling. As soon as this signal detects that the vehicle is rolling during roll monitoring, the EMF actuators are immediately re-tensioned. This process involves the EMF actuators being fully supplied with current for 100 ms to increase the tensioning power. A waiting period of 400 ms then follows. If the vehicle rolls again, the re-tensioning process is repeated (maximum three times). If the system detects that the vehicle is still rolling after the third re-tensioning process, the functions ends with a fault entry in the fault memory.