Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Central Locking System: Introduction
The Car Access System (CAS) monitors all the processes in the central locking system. The CAS control unit is the master control unit for the central locking.
Up to 09/2005, the central locking system on the front doors is actuated by the door modules (driver's door module and front passenger door module).
- From 09/2005
The door modules are discontinued. The central locking system on the front doors is actuated by the body gateway module (KGM).
The following central locking drives are actuated by the body basic module (KBM).
- Rear doors (E60, E61 only)
- Rear lid
- Fuel filler flap
- Rear window (E61 only)
The CAS control unit uses the requests from various operating points (e.g. lock cylinder, remote control) to decide what needs to be done:
- Locking/deadlocking the central locking system
- Unlocking the central locking system
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.