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.
Crash unlocking
A crash is recognized as such by the MRS control unit (E87, E90, E91, E92) or ACSM control unit (E93). A crash signal is transmitted by the CAS control unit. The message is sent on the K-CAN. The CAS control unit unlocks the vehicle.
All operating points are disabled when there is a crash signal. This prevents unintentional actions of the central locking system from occurring due to short circuits caused by the accident.
After a crash, the central locking system cannot be operated until terminal R has been switched off for at least 3 seconds.
(MRS = "Multiple Restraint System"; ACSM = "Advanced Crash Safety Module", alternatively known as the "Crash Safety Module")
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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.