Alarm going off

[Rocket]

My alarm on my 2004 E85 3.0 litre keeps going off. I tried disconnecting the bonnet switch and it still went off. I disabled the interior sensor by pressing the key fob twice when locking and this seems to have stopped the alarm activating. I have INPA and a cable and after reading the fault codes I get a fault 8A 21 in regard to the alarm. Does anyone have any info on what error code 8A 21 is.

I would add that this code was read in information memory not error memory. ( I have no clue on the difference )

 

[oldgitdave]

I had the exact same issue with mine. I never looked at the codes but for me it turned out to be a low battery. Sometimes the car would be left locked for a week or two & then the alarm would go off randomly. Even though it started fine I found that after a short drive when locked for an hour or so it'd go off. I put it on the Ctek now if I'm going to leave it parked up for any length of time & have had no issues since.

 

[Rocket]

Thanks for that. I've not used it a lot as it is my second car. I do start it and run it every few days but it may be worth charging the battery and see if that helps. I'll charge it for 24 hours on my CTEK and will report back in a day or two.

 

[buzyg]

I had the exact same issue with mine. I never looked at the codes but for me it turned out to be a low battery. Sometimes the car would be left locked for a week or two & then the alarm would go off randomly. Even though it started fine I found that after a short drive when locked for an hour or so it'd go off. I put it on the Ctek now if I'm going to leave it parked up for any length of time & have had no issues since.

That's interesting. Mine has gone of a number of times in the past. Never got to the bottom of why, but the battery did occur to me. Has not done it since last summer, so whatever the cause, it is working fine for the moment.

 

[Rocket]

I charged the battery for 24 hours with my CTEK charger, I gave it a full reconditioning charge. I locked the car this morning with the interior sensor activated and it has been fine for 3 hours. I have not moved the car since I was getting the alarm going off a couple of days ago. The battery came with the car when I bought it and I'm sure the guy said he had put a new one on while he owned the car, I guess it is 4 or 5 years old. Fingers crossed low voltage was the problem. (the car started fine so the battery was not flat). If the alarm starts going off again I will post again. The car is getting no use at the moment but I have been starting it every few days and running the engine for 15 mins or so. During the winter I charge it every week or two with the CTEK.

 

[buzyg]

I charged the battery for 24 hours with my CTEK charger, I gave it a full reconditioning charge. I locked the car this morning with the interior sensor activated and it has been fine for 3 hours. I have not moved the car since I was getting the alarm going off a couple of days ago. The battery came with the car when I bought it and I'm sure the guy said he had put a new one on while he owned the car, I guess it is 4 or 5 years old. Fingers crossed low voltage was the problem. (the car started fine so the battery was not flat). If the alarm starts going off again I will post again. The car is getting no use at the moment but I have been starting it every few days and running the engine for 15 mins or so. During the winter I charge it every week or two with the CTEK.

Your Zed will sit happily for weeks without need to run the engine. Just keep the battery charged. The most likely thing to give you issues when not running, aside from the battery, are the brakes binding. Better to take it round the block when we can, as that warms the gear box and running gear through.

 

[enuff_zed]

I charged the battery for 24 hours with my CTEK charger, I gave it a full reconditioning charge. I locked the car this morning with the interior sensor activated and it has been fine for 3 hours. I have not moved the car since I was getting the alarm going off a couple of days ago. The battery came with the car when I bought it and I'm sure the guy said he had put a new one on while he owned the car, I guess it is 4 or 5 years old. Fingers crossed low voltage was the problem. (the car started fine so the battery was not flat). If the alarm starts going off again I will post again. The car is getting no use at the moment but I have been starting it every few days and running the engine for 15 mins or so. During the winter I charge it every week or two with the CTEK.

Your Zed will sit happily for weeks without need to run the engine. Just keep the battery charged. The most likely thing to give you issues when not running, aside from the battery, are the brakes binding. Better to take it round the block when we can, as that warms the gear box and running gear through.

As a general rule of thumb, I have always worked on the understanding that it takes around 7 miles of normal driving to put back the charge used to start a car.
I will admit that this info came to me a good 35 years ago, and things have moved on a bit since then, but I am still sure that just starting and running a car for a short while may not do the battery a lot of good.
Plus, as mentioned, you need to get everything warmed up properly to burn off any condensation as well.

 

[Rocket]

Oh well after 10 hours the alarm has gone off again so it does not seem to be the battery.

 

[ben g]

Mine keeps doing this. I replaced the bonnet switch last year and after a while it started again, so I removed the bonnet switch last week and a couple of days ago the alarm went off at 6:30am

I didn't know you could disable the interior sensors. Do you just press the lock button on the fob twice? How do you know the sensors are disarmed, or do you just have to trust they are?

I'm not using the Z4 due to the situation (I'm furloughed for at least a month), so I don't fancy being woken up early again.

 

[Rocket]

Yes just press the key fob twice. To see if the double press of the key fob works position yourself so you can see the flashing LED at the bottom of the interior mirror. When you press the fob for the second time the LED will do one long flash (maybe half a second or so). It seems to work on my car OK.

 

[ben g]

Yes just press the key fob twice. To see if the double press of the key fob works position yourself so you can see the flashing LED at the bottom of the interior mirror. When you press the fob for the second time the LED will do one long flash (maybe half a second or so). It seems to work on my car OK.

Cheers, I'll give that a try. My neighbours will love me if it means no more wayward alarm calls :lol:

 

[Rocket]

I locked the car yesterday with the double press of the key fob and all was well overnight and this morning. I was fiddling with the car this morning and when I had finished I locked it normally with the interior sensors activated. The alarm went off after 5 mins. I have now locked it again using two presses and all is ok again.

I can carry on pressing the key twice to lock as it is no real hardship but a bit annoying that the alarm is not functioning properly. I read the error codes again today and the one relating to the alarm was 8A 22. I don't know what the code means but my guess is it just says the alarm activated again for the 22nd time.

 

[Jl-c]

I charged the battery for 24 hours with my CTEK charger, I gave it a full reconditioning charge. I locked the car this morning with the interior sensor activated and it has been fine for 3 hours. I have not moved the car since I was getting the alarm going off a couple of days ago. The battery came with the car when I bought it and I'm sure the guy said he had put a new one on while he owned the car, I guess it is 4 or 5 years old. Fingers crossed low voltage was the problem. (the car started fine so the battery was not flat). If the alarm starts going off again I will post again. The car is getting no use at the moment but I have been starting it every few days and running the engine for 15 mins or so. During the winter I charge it every week or two with the CTEK.

Your Zed will sit happily for weeks without need to run the engine. Just keep the battery charged. The most likely thing to give you issues when not running, aside from the battery, are the brakes binding. Better to take it round the block when we can, as that warms the gear box and running gear through.

As a general rule of thumb, I have always worked on the understanding that it takes around 7 miles of normal driving to put back the charge used to start a car.
I will admit that this info came to me a good 35 years ago, and things have moved on a bit since then, but I am still sure that just starting and running a car for a short while may not do the battery a lot of good.
Plus, as mentioned, you need to get everything warmed up properly to burn off any condensation as well.

I also was told ( years ago, granted ) that it will take 20 minutes of running to put the charge back into a battery that has just started a car. Can you not just leave the CTek connected all the time you are not using the car? Assuming it is the battery conditioner and not just a charger; it was designed to be left on all the time the car is laid up.

 

[Rocket]

Your Zed will sit happily for weeks without need to run the engine. Just keep the battery charged. The most likely thing to give you issues when not running, aside from the battery, are the brakes binding. Better to take it round the block when we can, as that warms the gear box and running gear through.

As a general rule of thumb, I have always worked on the understanding that it takes around 7 miles of normal driving to put back the charge used to start a car.
I will admit that this info came to me a good 35 years ago, and things have moved on a bit since then, but I am still sure that just starting and running a car for a short while may not do the battery a lot of good.
Plus, as mentioned, you need to get everything warmed up properly to burn off any condensation as well.

I also was told ( years ago, granted ) that it will take 20 minutes of running to put the charge back into a battery that has just started a car. Can you not just leave the CTek connected all the time you are not using the car? Assuming it is the battery conditioner and not just a charger; it was designed to be left on all the time the car is laid up.

Yes I can. But i have not had any battery problems. The battery charging was just brought up in this thread as a maybe cause of the alarm going off. But even when we are locked down I still drive the car 50 metres to wash it once in a while and sometime I move it around the farm to be nearer workshop or barn etc particularly now I am at home 99.99% of the time.

 

[Ewazix]

With any electrical problems on these cars you have to completely eliminate it being a low battery before wasting time looking elsewhere, have you voltage checked it after a being sat a for a few days? With a volt meter you are looking for at least 12.4 Volts on a good battery. Anything less will cause problems.

It looks like you have eliminated the bonnet switch and information code 8A relates to interior alarm activation, so I would be suspecting other sensors and connections like the tilt unit (in centre consul or combined with the siren depending on model) locking fuel cap activator / switch (will be inside the boot, possibly damaged when people pull the flap when locked?) or the alarm siren (rear wheel arch behind arch liner) or the GM5 locking control module (behind glove box) this communicates locking status to the alarm system. I'd always be focusing on any areas which have had damage, aftermarket kit fitted, water ingress or repairs first. Happy hunting and let us know if you crack it

TIS re Tilt unit https://workshop-manuals.com/bmw/z_series_e85/z4_2.5i_n52_roadst/2_repair_instructions/65__audio_navigation_and_information_system/75__anti-theft_alarm_system/1_ra__overview_of_control_units_modules/

Tilt and siren http://www.unofficialbmw.com/images/6115EN.pdf

GM5 https://z4-forum.com/forum/viewtopic.php?f=34&t=102586

 

[Rocket]

With any electrical problems on these cars you have to completely eliminate it being a low battery before wasting time looking elsewhere, have you voltage checked it after a being sat a for a few days? With a volt meter you are looking for at least 12.4 Volts on a good battery. Anything less will cause problems.

It looks like you have eliminated the bonnet switch and information code 8A relates to interior alarm activation, so I would be suspecting other sensors and connections like the tilt unit (in centre consul or combined with the siren depending on model) locking fuel cap activator / switch (will be inside the boot, possibly damaged when people pull the flap when locked?) or the alarm siren (rear wheel arch behind arch liner) or the GM5 locking control module (behind glove box) this communicates locking status to the alarm system. I'd always be focusing on any areas which have had damage, aftermarket kit fitted, water ingress or repairs first. Happy hunting and let us know if you crack it

TIS re Tilt unit https://workshop-manuals.com/bmw/z_series_e85/z4_2.5i_n52_roadst/2_repair_instructions/65__audio_navigation_and_information_system/75__anti-theft_alarm_system/1_ra__overview_of_control_units_modules/

Tilt and siren http://www.unofficialbmw.com/images/6115EN.pdf

GM5 https://z4-forum.com/forum/viewtopic.php?f=34&t=102586

Thanks for the info. Just to update for anyone interested, the two presses on the key fob to deactivate the alarm works a treat. I get no problems when using this. I shall just keep using this method for now and wait until i get enough enthusiasm to tackle any the above you have mentioned. What you have said is pretty much the conclusion I had come to I will check the battery voltage. Thanks again.

 

[Rocket]

The car came off charge 8.00 am Friday and the voltage now 11.20 Sunday is 12.35 volts. I may try putting the car back on the CTEK charger and setting the alarm while the charger is connected. That should at least make sure the voltage is good while the alarm is set.

 

[Rocket]

Update:

I have been monitoring the battery since Sunday and now (Thursday morning) it was 12.15 volts. It appears this battery is not in top condition and I may get another. It has not failed to start the car at any time but the voltage readings suggest it is passed it's best. Interestingly the alarm has not activated at all for several days even with the battery at a low level. I feel witchcraft is at work.

 

[Rocket]

Another update:

It has been 2 weeks since the alarm last went off and everything is fine. I have not done anything to try and solve the problem, it has just sorted itself out. The battery voltage was at 11.9 volts when I just tested it, 11.9 volts is a much lower voltage than when I was getting problems with the alarm going off. Yesterday I put the roof down and set the alarm. Then I waved a broom about in the footwell and the alarm activated, so I know the alarm is still functioning.

Two weeks ago the alarm was being a real pain, now it is fine and I have done nothing. :idunno:

 

[enuff_zed]

Another update:

It has been 2 weeks since the alarm last went off and everything is fine. I have not done anything to try and solve the problem, it has just sorted itself out. The battery voltage was at 11.9 volts when I just tested it, 11.9 volts is a much lower voltage than when I was getting problems with the alarm going off. Yesterday I put the roof down and set the alarm. Then I waved a broom about in the footwell and the alarm activated, so I know the alarm is still functioning.

Two weeks ago the alarm was being a real pain, now it is fine and I have done nothing. :idunno:

Does this coincide with the two weeks of warm, dry weather we just had? Depending whereabouts you're located?
To me, this may suggest a damp connection which has now dried out.