And so it goes….

[workingonit]

Originally Posted by Henn28

Workingonit, you are correct in that there should be a siren there assuming your car had the factory alarm system. I am not sure if any e53 x5s were sold without alarms, but I sort of doubt it. Mine (siren) sits exactly where you describe and is strangely easy to get to, for a BMW!...

Happy to send you my questionable siren to troubleshoot with if you want, after I get the new one in next week.

My X5's VIN shows S302A Alarm system, so it must've been removed, unless the 2001 model was meant to sound the horn (I'm confused, the diagram shows "horn" not "siren").


If there should be a "siren" mounted there, and isn't, then since some of the previously installed optional electronics have been removed,

• S645A BMW US Radio
• S650A CD player
• S661A Radio BMW Business (C43)

I shouldn't be surprised.

Thanks, but no, keep your siren. I'll just keep mine as it is; I really rarely park it where it would be theft-prone, and it is usually next to

• much better (flashier, more expensive)
• newer (mine's 21yo, others are often brand new)
• more lucrative (how much would a chop shop pay for a worn E53?)

targets.

[Henn28]

Got home today to an FCP box with the new alarm horn. The fuse was pulled due to the alarm going off again as I was walking away from the car in the parking garage 4 days ago, so I popped the horn I n and jammed the fuse back in. The thing acts like it should with arm/dearm beeps, and the alarm works 4.0 when test it via the motion detector.

Hopefully this will be the closeout post on this thread! An intermittently failing alarm horn (integrated battery likely) causing the thing to sound off after locking the car, but with no codes. New alarm horn hopefully fixed it.

[Henn28]

Follow-up: new alarm siren/horn fixed it - no problems for roughly 6 weeks after installing the new siren. More money than I wanted to spend on this problem, but with the internal battery I figured a used one could be on deaths doorstep too. 22 years isn’t bad from an OE rechargeable battery.