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E90 General Vehicle Electrical
Control Modules for Comfort Access Function
Car Access System 2 (CAS2)
As soon as the CAS2 receives a request signal it must verify if a valid ID Transmitter is
located with range of the antenna. CAS2 requires that the antenna in the area of the
request transmit a request for validation to the ID Transmitter.
The ID transmitter transmits a signal to the remote control receiver, which in turn forwards
the signal to the CAS2 where the signal is checked to be valid and belonging to the vehi-
cle. Only if the check/authentication, which takes a few milliseconds, is successful will
the CAS2 forward the request to activate the specific function.
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.
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.
Comfort Access Control Module
The Comfort Access Module controls/activates the antennas located on the exterior and
interior of the vehicle, plus reads/transfers the data received from the Electronic Outer
Door Handle Module to the CAS2.
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