Alarm constantly goes off

[ggrelish]

Hey all- my alarm will constantly go off after I lock the car. Anywhere from immediately when I lock it to 15 minutes after. This happens multiple times every day. I had a jb4 plugged in, thought it was that, but I unplugged it and the alarm still goes off. I have a dash cam hard wired in, thought it was that, but I unplugged it and the alarm still goes off.

This just started happening recently in the past couple of months, while I've had the jb4 and dash cam for a while, so I don't think it's either of those causing the issue.

Has anyone experienced this before? Anybody know the cause?

Final update:

I got Bimmerlink as a user suggested, and it showed 2 errors in the Roof function center:
DE8C5E: LIN: Sine doesn't answer
801A55: Theft alarm system: Alarm- details in alarm memory.

I didn't know how to get into the alarm memory, but I searched the codes and it seems like there are some BMW owners with similar issues, with the likely culprit being the alarm siren.

I ordered the replacement part:
Toyota part number: 89040-WAA02

I couldn't find the part anywhere except for California, so I took the part out of my car to see if it was BMW made and it is.
BMW part numbers:
65755A83298 (old)
65755B61723 (new)

It was out of stock everywhere. Toyota ended up getting it to me the quickest. The new part from Toyota actually had Toyota branding this time, not BMW, but it appears the same, obviously.

The part is located under the driver's side rear quarter-- take off the back bumper and the plastic part under it.

Once I got it installed and everything put back together, I now have the chime back when I lock/unlock my car. Those 2 codes are not there anymore when I scan, and my alarm is not randomly going off. So this was definitely the fix.

Hopefully this was a fluke, but I hope this helps any future supra/bmw owners that have this alarm problem.

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[J29DB03]

Anything plugged into the OBD port?

 

[Thraxbert]

I have a sneaking suspicion, as does the poster above me, that there's still something plugged into the OBD port. I'll venture an even more precise prediction that there's some sort of GPS tracker sitting between the real OBD port and the port OP has actually been plugging into.

For example, this product gives you a real OBD port... Except it gets Y'd under the dash to a GPS box that gets hidden. Unless you were specifically looking for this product, it would look and feel like a standard OBD port under the dash. And I think the alarm is going off because it has some sort of battery backup that is now dying, triggering the OBD alarm when there's no vehicle 12V power going to the device.

Hope I'm wrong.

 

[exe36m3]

Any tennis balls nearby?
Its a stretch yes.

 

[ggrelish]

There's nothing plugged into the obd port, I made sure of that.

 

[J29DB03]

What model year is it?

 

[razorlab]

There's nothing plugged into the obd port, I made sure of that.

As in, you looked above the port to make sure it's the OEM port and not a Y to something else under the dash?

 

[ggrelish]

It's a 2022.

Yes, I looked to make sure there was nothing above it. I'll verify again, but I didn't see anything the first time. I looked through a ton of threads where people said it was something in the obd port, so that was the first thing I checked, but I will double check.

 

[Thraxbert]

My only other guess is that the battery is critically low, but not low enough to trigger a low battery warning on the vehicle's HUD. It has been my experience with BMW platforms that they are absurdly sensitive to low state of charge, and they tend to spit out all sorts of bizarre and inexplicable behaviors when the battery is low or dying. I mostly have experience with Hyundai, Suzuki, and Toyota vehicles, but I've never in my life seen those brands match the level of weirdness that BMWs put off when the battery is dodgy.

Many people have come through here with electrical gremlins, swearing up and down that it's not the battery. But it always seems to be the battery.

 

[J29DB03]

? That right there. Being a ‘22 check the battery or, in my opinion/experience, just replace it with a lithium battery. These AGMs have the ability to be great one day and completely dead the next without any warning. If it is the battery be glad you got a heads up before it completely left the building.

Bonus: It was nice enough to go out on a holiday weekend so you could take advantage of a sale. Mine shit the bed on me the Sunday before Memorial Day last year. Annoying, but no less courteous.

 

[Rocksandblues]

open hood. slam hood shut.

 

[concept]

My only other guess is that the battery is critically low, but not low enough to trigger a low battery warning on the vehicle's HUD. It has been my experience with BMW platforms that they are absurdly sensitive to low state of charge, and they tend to spit out all sorts of bizarre and inexplicable behaviors when the battery is low or dying. I mostly have experience with Hyundai, Suzuki, and Toyota vehicles, but I've never in my life seen those brands match the level of weirdness that BMWs put off when the battery is dodgy.

Many people have come through here with electrical gremlins, swearing up and down that it's not the battery. But it always seems to be the battery.

Our Lexus 2006 RX400h would display something like "Shift into Park before turning off vehicle." That indicated a weak battery.
My 2014 Mazda 3S GT with tech pack would display "i-Eloop failure: Yep, you guessed it - weak battery.

But never did I experience an alarm going off. I would imagine that if a door switch somehow were to send a signal that the door was being opened, ...........

 

[ShakaDaKine]

If all else checks out, it could be the alarm module. I believe someone else on the forum had issues with the alarm going off, and the module was replaced under warranty.

 

[ggrelish]

Battery had 12.51v after sitting all night, right before I drove this morning, so I don't think that's the issue.

I took the panel off under the dash to look at the obd2 port again, and there's nothing plugged into it, and nothing spliced into the wires.

 

[razorlab]

Did you do a full scan with something like Bimmerlink or Protool? That could help move from just guessing.

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