Alarm

[BCS_ZHP]

Yesterday, get to work and park the 540 outside my office in the morning. It's a hot day but not as hot as it has been that 1st week of July. Traffic where I park is minimal, maybe half a dozen cars pass per day. About 3:30, after sitting for over 7 hours, my car alarm goes off. Go out and open the car to turn off the alarm, relock the car and no recurrence. Has anyone ever had this happen?

Called the dealer and described the situation. No definitive answer, the service writer opined that heat waves in the car could have set it off if it was parked in direct sunlight for an extended period -- it was. I had the car tinted at 35% on Monday, thought the tint helped reduce inside temps, I dunno?

[ryankokesh]

that's weird...

[BCS_ZHP]

Okay, it just did it again, the alarm sounded off after 4 hours sitting outside. Weather is in the high 80's and overcast, not as hot as yesterday afternoon. Any ideas? The only two changes over the last week were a cooling system refresh last Friday and tinted windows (side & rear) done on Monday.

[ryankokesh]

Disable the alarm? :dunno I know there's a way to lock it that doesn't arm it.

[BCS_ZHP]

Now thinking back, I bought a new programmable key and they programmed it to the car on July 3rd. Possibly the service writer who set this key up to function with the car increased the sensitivity of the alarm -- is that a viable theory?

[WOLFN8TR]

Yesterday, get to work and park the 540 outside my office in the morning. It's a hot day but not as hot as it has been that 1st week of July. Traffic where I park is minimal, maybe half a dozen cars pass per day. About 3:30, after sitting for over 7 hours, my car alarm goes off. Go out and open the car to turn off the alarm, relock the car and no recurrence. Has anyone ever had this happen?

Called the dealer and described the situation. No definitive answer, the service writer opined that heat waves in the car could have set it off if it was parked in direct sunlight for an extended period -- it was. I had the car tinted at 35% on Monday, thought the tint helped reduce inside temps, I dunno?

I have the same tint and it's 110 degrees here and my alarm never goes off while sitting out in the heat.


Bayerische-Motoren-Werke

[Meric]

Did you leave any of the windows/sun roof open. ? Motion sensor is very sensitive.

[BCS_ZHP]

It went off a 2nd time today, so I called a different dealer, a different service advisor and explained the situation, asked if the new key programming could be at fault. He didn't think so but rather suggested the hood open sensor can be so sensitive that it detects the hood expanding ever so slightly when it sits in direct sunlight. Bingo!

When I did the coolant system refresh last Friday night, I noticed that sensor was unplugged and reconnected it. I thought I had accidentally left it unhooked when I bled the brakes a few days earlier. (The 540 has 2 cabin air boxes/inlets, the brake reservoir is located under the air box on the drivers side.). So for now I unplugged the sensor and will look at it later tonight to see if its adjustable to make better contact with the hood, or replace it if necessary.

[johnrando]

Good find. Who woulda thought?

[BCS_ZHP]

It's been over an hour in direct sunlight with no recurrence, maybe (fingers crossed) that was it.

John -- just dumb luck that I got a service advisor who even fathomed a guess, and a guess that appears to be correct.

[MrMaico]

If it's like the ones on the E46 it's not adjustable. I would look for a piece of maybe 1/8" thick rubber and cut a circle out of it and glue it onto the top of the switch button and see if that cures it. Or I suppose it could be glued to the bottom of the hood too.

[BCS_ZHP]

True, no adjustment so for now it will just remain unplugged.

[quikryptonite]

I thought I had the same thing happen to me the other day. I came out of Zupas and my lights were flashing. I turned it off and was rather baffled. However, when I started the car, the indicator on the dashboard showed that the trunk wasn't shut. I must have sat on my key somehow and had pressure on the trunk release button long enough to trigger the alarm? Only thing I can think of. Sounds like you have a different problem though. Good luck.

[nike001]

Hood sensor. Common problem

[Rovert]

Yup my hood sensor had issues. I fixed it with liquid lubricant. No problems anymore since I did that!

[danewilson77]

Yup my hood sensor had issues. I fixed it with liquid lubricant. No problems anymore since I did that!

What lube did you use?

Sent from Williamsburg, VA USA

[mr hish]

i had the same problem with my dad's 528 it turned out to be the hood open sensor so i unplugged it . problem solved.

[Rovert]

What lube did you use?

Sent from Williamsburg, VA USA

LOL anything that was slippery? My car was at my aunts and she gave me something she uses on who knows what.... :S I say a nice shot of WD40 or alike in the two little holes on either side of the button switch would do good. Squirt it in then press the button many times to get the lube worked in. :D

[cakM3]

I had that same problem in my ZHP in spring and found out my hood switch was causing this issue. Replaced the switch and no more false alarms :)


Sent from my iPad using Tapatalk HD

[quikryptonite]

This is the right part even though it says for M3 with SMG, correct? 61319119052

ECS Tuning - Hood Sensor (http://www.ecstuning.com/Search/61319119052/ES168350/)

[cakM3]

This is the right part even though it says for M3 with SMG, correct? 61319119052

ECS Tuning - Hood Sensor (http://www.ecstuning.com/Search/61319119052/ES168350/)

Looks like the right part. Shouldn't be different.

[quikryptonite]

I had that same problem in my ZHP in spring and found out my hood switch was causing this issue. Replaced the switch and no more false alarms :)


Sent from my iPad using Tapatalk HD

Wow, does a repair job get any easier than replacing the hood switch? I submit that it does not!