You just need to plug it in to the trailer and tap the brake pedal. The alarm will be generated immediately if it is going to trip.



I agree, if the total weight of the trailer is only 2200 lbs, you might be fine without a brake controller. A few times I've forgotten to put the brake controller back in (since I take it out of the car during the winter when I'm not towing) and had to stop abruptly with my trailer (which is about 4,000 lbs loaded) and it stopped pretty fine. A bit slower, but not dangerous by any means. The E53 has really good brakes, even the 3.0.

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2003 3.0 5MT Topasblau
Purchased in 2016 and sold in 2024
2012 35d Platingrau