BMW Questions? Ask a BMW Repair Expert for Answers.
The cable in the trunk is the mechanical override, but if that isnt working you can cut the cables going to the wheels. The new unit comes with those cables.
Glad to hear you got the vehicle mobile again. You can leave the connector connected you will just get a warning saying brake malfunction.
The alarm shouldn't play a role in the alarm system. When you hit the button twice on the fob you are disabling the interior motion sensor. I would suspect an issue with that sensor.
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