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...please add a bit more context to your situation...you may get some better help...or find out there may be a better way to accomplish what ever it is that you're trying to get around. :)

If you've exhausted a lot of other measures...we have no way of knowing what they were (unless you tell us by giving more context to your situation)...so answering your ambiguous question may not be the right answer you need.

We want to be of help...but help us help you better by giving us some details about your situation. Why do you want to power down your anti-theft alarm siren system? :)

NEVER MIND
the above...I just ran across one of your other threads where you DO give the context as to what is going on with your alarm siren system:

I have a 2002 e39 540i auto....it sat for the last 7 months and I at first I tried to just charge up the old battery, that worked to get the car started and to my house, but the headlights started flashing on and of randomly even with the car off and the alarm would go off for no reason at all and it eventually went dead overnight....I replaced the battery today and it fired right up, I went and took it for a shakedown ride and it ran ok other than occasionally it would start to shake around 50mph especially after accelerating a bit aggressively but sometimes it wouldn't, the alignment is good, it tracks strait.....so that's one issue that I have.....now to the one that really worries me.....the car alarm is still going off for no reason.....What's causing that....how do i fix it.....I'm on a budget and would like to fix it myself.....please help me figure this out....I love this car and it deserves to be running right!

The car's alarm siren has its own internal rechargeable battery. If the car sat for a long time...the alarm siren's battery has probably discharged to the point that it may be damaged and is not holding its own charge. Any drop in voltage will be interpreted as power being cut to the car...thus the alarm will sound off.

Since you've already disconnected the hood sensor...it obviously is not the culprit for the false triggering. You can either try replacing the alarm siren or unplugging the electrical harness to the alarm siren if you want to just totally do-a-way with it entirely. It is located behind the right rear wheel well liner (passenger side).

Or you can try to recharge the alarm siren's battery. As mentioned in the info below...the alarm siren's battery is CHARGED when the car is in an UNARMED state (unlocked). If you have a battery charger or battery tender/trickle charger...you could hook it up to the jump start terminals in the engine bay...and leave the car UNLOCKED over-night (or at least for a good 12-24 hours) and see if that gets the alarm siren's internal battery charged up enough that it won't false trigger for low voltage.

 

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