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E90 General Vehicle Electrical
Car Access System 2 (CAS2)
As soon as the CAS2 receives the lock/unlock signal from the remote control receiver, it
checks whether the identification transmitter is valid and belongs to the vehicle. Only if
the check/authentication, which takes a few milliseconds, is successful will the CAS2 for-
ward the request to activate the central locking.
The CAS2, serves as the master control module for the central locking system, as it
issues the enable signal to activate a lock/unlock function. An enable status signal is
transmitted to the JBE from CAS2 via K-CAN.
Signal Path: Remote control to remote receiver to CAS2; or
Central lock button input to CAS2;
Enable signal from CAS2 to JBE via K-CAN (if all doors are closed)
Door status signal from FRM to JBE via K-CAN then JBE via K-Can to
CAS2
Example: The request to lock the vehicle, is not executed while the driver's door is
open.
Junction Box Electronics Control Module (JBE)
The Junction Box Electronics Control Module is responsible for implementing the
lock/unlock operation for the entire vehicle, as it contains the lock/unlock relays which in
turn drive the respective lock/unlock motors.
The following central locking relays are activated by JBE:
• Driver's door
• Rear doors
• Front passenger's door
• Fuel filler flap
The central locking function for the trunk lid is activated directly via a power output stage.
Signal Path: Enable signal from CAS2 to JBE via K-CAN; JBE activates lock/unlock func-
tion via direct activation of relay(s)
Footwell Module (FRM)
The Footwell Module (FRM) monitors the hall sensors of the door contacts to determine
if a door is open or closed. CAS2 indirectly obtains the door status information and uses
the information to determine if an enable signal is to be provided to the JBE.
Signal Path: Door contact signals input to FRM; Door status signal from FRM to JBE via
K-CAN then forwarded from JBE via K-Can to CAS2.
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