Author Topic: Car alarm going off in the middle of the night  (Read 4080 times)

Online sjw

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Car alarm going off in the middle of the night
« on: 21 November 2019, 18:46 »
Hi all,

I'm having a bit of an issue with my car alarm going off seemingly at random. I would say it has happened four out of the last 7 nights, between 23.30 and 02.30. This is obviously really annoying as even once the chirping has stopped, the lights continue to flash for about another 15 minutes. SO I have to get up and stop it. Not to mention annoying the neighbours....

Now, I've recently (2-3 weeks ago) installed a JB4 which obviously required disconnecting the battery etc. So I'm wondering if I've knocked something here.

I have a few other ideas -

- The battery wasn't reconnected properly, and the cold is making the connections flaky (I found out the hard way that if you disconnect the battery with the doors locked, the alarm blasts. I've retightened the connections now.
- I've knocked some wiring underneath the passenger side dash, which might be where the wiring for the alarm is? I don't know
- My dashcam is set to be on all the time. This hasn't been a problem up until now, but I've disabled this for now in case it was draining the battery
- There's an insect of some sort in the car!

Any ideas? I really don't want to take it to a garage as I've got the JB4 installed now and it was a pain in the arse! Don't really want to have to take it off again in less than a month

Mk7.5 GTI PP (not that it probably matters)

Thanks people  :smiley:

Offline Watts

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Re: Car alarm going off in the middle of the night
« Reply #1 on: 21 November 2019, 18:49 »
Seems odd that it only goes off in the early hours. Are you sure no-one is trying to get in? Other than that, not a clue, sorry.
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Online sjw

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Re: Car alarm going off in the middle of the night
« Reply #2 on: 21 November 2019, 19:22 »
Yes that's what I thought. That's why I was thinking about temperature.

It's gone off when parked behind my girlfriend's car with no way to take it off the driveway as well. So I'm not sure why someone would try to get in then. I'll have to check the dashcam

Offline Gnasher

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Re: Car alarm going off in the middle of the night
« Reply #3 on: 21 November 2019, 20:06 »
Complete guess but could it be voltage drop from having the jb4 on the car as well as the dashcam? It'll get colder in the night (as you already suspect) which makes batteries less efficient at a guess.

Try uninstalling the jb4 and see if that cures it would be my next move, just to check.
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Offline mcmaddy

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Re: Car alarm going off in the middle of the night
« Reply #4 on: 22 November 2019, 06:39 »
I've got front and rear dash cam and never had the alarm go off due to battery being low. Saying that mind the dash cam has settings to prevent killing the battery. Why don't you get your battery checked and eliminate that if it's ok.
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Offline Rob_benton

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Re: Car alarm going off in the middle of the night
« Reply #5 on: 22 November 2019, 07:09 »
Common problem on my old BMW Z4 was the bonnet sensor.
I don’t know where it is on the Golf but maybe worth giving it a few pushes and lubricating it. 10 second job.
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Online sjw

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Re: Car alarm going off in the middle of the night
« Reply #6 on: 22 November 2019, 07:39 »
Common problem on my old BMW Z4 was the bonnet sensor.
I don’t know where it is on the Golf but maybe worth giving it a few pushes and lubricating it. 10 second job.

The alarm didn't go off last night, thank god! I've unplugged the dash cam, tightened the battery terminals, and obviously re shut the bonnet. If it happens again the sensor is where I'll look

Offline dean5125

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Re: Car alarm going off in the middle of the night
« Reply #7 on: 22 November 2019, 08:26 »
… And just something you mentioned in the OP, turn off the internal monitoring for the alarm for a couple of nights, quick job and will eliminate one more possible!

nothing worse than electrical issues..... especially intermittent ones, good luck!   
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Online sjw

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Re: Car alarm going off in the middle of the night
« Reply #8 on: 22 November 2019, 09:37 »
… And just something you mentioned in the OP, turn off the internal monitoring for the alarm for a couple of nights, quick job and will eliminate one more possible!

nothing worse than electrical issues..... especially intermittent ones, good luck!

Yup, that is next on my list after the bonnet sensor!

I'm hoping it is just a coincidence and not to do with the JB4, as there was a couple of days before it started happening. The car is FILTHY though, so maybe it is dirt on a sensor. Fingers crossed I can get it sorted!

Offline Snoopy

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Re: Car alarm going off in the middle of the night
« Reply #9 on: 22 November 2019, 09:42 »
When ultrasonic sensors ho faulty they trigger with tempurature drop or rise. My first port if call would be to turn off interior sensors and see if that fixes it. Then as said bonnet sensor. You could get it scanned as that would show whats triggered the alarm.
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