e39 M5 alarm problem
Discussion
Evening all
I've been having some intermittent problems with my M5.
Recently, I have tried to unlock the car using the fob and nothing happens. No buttons work.
If I then open the door using the key, the alarm sounds and the hazards flash. I can get into the car and start the engine, even drive off, with the alarm still going.
But after a 1 minute drive with alarm sounding and hazards still flashing, I park up and the fob now works when I get out and lock the car. I don't think its the fob's capacitor failing as none of the fobs work when I try them whilst the alarm is going off. But they work after a short while.
An internet search has shed little light on the matter except to lock the car with the rear door open using the master central locking button.
Help - I'm stuck!
Thanks
Ben
I've been having some intermittent problems with my M5.
Recently, I have tried to unlock the car using the fob and nothing happens. No buttons work.
If I then open the door using the key, the alarm sounds and the hazards flash. I can get into the car and start the engine, even drive off, with the alarm still going.
But after a 1 minute drive with alarm sounding and hazards still flashing, I park up and the fob now works when I get out and lock the car. I don't think its the fob's capacitor failing as none of the fobs work when I try them whilst the alarm is going off. But they work after a short while.
An internet search has shed little light on the matter except to lock the car with the rear door open using the master central locking button.
Help - I'm stuck!
Thanks
Ben
I'm not an expert, but it sounds like it could be the battery in the key failing. I don't think you can change the battery without cutting open the key.
Edit - have you tried re-syncing the keys? I think there is a section in the owners manual that explains it. I've not got mine to hand atm.
- ok I went out and checked the manual, couldn't see a section on resyncing the key but it does mention the master key is charged everytime you put it in the ignition. If you other master key has the same issue it could also be the battery I guess.
To re-sync Key Fob- I pulled this off another forum:
1. Sit in your car with doors shut, and unlocked.
2. Place key in ignition and turn till you get to position 1, but take key out in LESS THAN 5 SECONDS
3. Press and hold the "unlock button" , and while you hold it in press the "lock button" 3 times in less than 10 seconds.
4. Release the "unlock button"
5. Wait for up to 10 seconds for locks to automatically lock, then unlock, which means then your key has been re-synced.
6. If this does not work the first time try again, Although I have used this method a few times and it has worked first time.
Hope that helps.
Edit - have you tried re-syncing the keys? I think there is a section in the owners manual that explains it. I've not got mine to hand atm.
- ok I went out and checked the manual, couldn't see a section on resyncing the key but it does mention the master key is charged everytime you put it in the ignition. If you other master key has the same issue it could also be the battery I guess.
To re-sync Key Fob- I pulled this off another forum:
1. Sit in your car with doors shut, and unlocked.
2. Place key in ignition and turn till you get to position 1, but take key out in LESS THAN 5 SECONDS
3. Press and hold the "unlock button" , and while you hold it in press the "lock button" 3 times in less than 10 seconds.
4. Release the "unlock button"
5. Wait for up to 10 seconds for locks to automatically lock, then unlock, which means then your key has been re-synced.
6. If this does not work the first time try again, Although I have used this method a few times and it has worked first time.
Hope that helps.
Edited by naefeart on Sunday 9th January 18:42
Hi,
As an initial diagnosis I'd say that the key battery was low on charge. The keys recharge while they're in the ignition slot so if the key battery is failing/low on charge then that could explain the problem. The batteries cannot be replaced so you'll need a new key if this is the fault. Another possibility is radio interference in the area that you unlocked the car initially, this is well known to affect the operation of the remote keys. Radio masts etc. Close by? Other possibilities are a faulty body electronics ECU (ZKE) as this controls the alarm/locking.
To give you some idea of the system; an aerial in the rear windscreen picks up the radio signap from the key, an aerial diversity unit seperates and amplifies this signal before it is sent to the ZKE. The ZKE encodes the signal and if correct, disarms/arms the alarm and then deadlocks/unlocks the central locking.
So quite a simple system really. Hope this has been of some help.
As an initial diagnosis I'd say that the key battery was low on charge. The keys recharge while they're in the ignition slot so if the key battery is failing/low on charge then that could explain the problem. The batteries cannot be replaced so you'll need a new key if this is the fault. Another possibility is radio interference in the area that you unlocked the car initially, this is well known to affect the operation of the remote keys. Radio masts etc. Close by? Other possibilities are a faulty body electronics ECU (ZKE) as this controls the alarm/locking.
To give you some idea of the system; an aerial in the rear windscreen picks up the radio signap from the key, an aerial diversity unit seperates and amplifies this signal before it is sent to the ZKE. The ZKE encodes the signal and if correct, disarms/arms the alarm and then deadlocks/unlocks the central locking.
So quite a simple system really. Hope this has been of some help.
I'd guess if you're running it at home on Jersey, it's not getting sufficient mileage to charge the keys; hence, the car won't recognise it, so alarms when you try to use it. I've seen a post somewhere on the net that suggested using an electric toothbrush induction charger, or a mobile phone mat style charger to keep it going - it may be worth searching for e46 & e53 key problems as well, as they use the same system, I believe. If the battery is too far gone & you're handy with a craft knife & a soldering iron they can be changed, but it's a bodge, rather than an official fix.
Almost certainly the key battery is faulty. I think the key is actually charged whilst driving on E39's (and subsequent models) so it is probably the case that the mile or so you are driving is giving it enough to just about lock/unlock it once or twice, but not much more.
If you're not unlocking it remotely with the BMW synchronised key, the alarm will think it's being nicked so will certainly go off. I would have thought that the immobiliser might have kicked in though? Perhaps if the key is in the ignition, that switches it off.
Battery should be pretty simple to replace yourself I would have thought, also relatively cheap (<£10?). You'll probably have to recode the key afterwards though, if it is the same as a couple of my old cars (they weren't BMW's though), you leave the drivers door open, turn the key in the ignition to the last point before the engine fires up, then press the lock button. All doors should lock and then pop open again and the key is re-syched. (disclaimer - I may have just told you a load of bull with the re-syching bit, but it's worth a go!!!)
EDIT - Must learn to read whole thread before replying! Naefeart's already got the recoding spot on!
If you're not unlocking it remotely with the BMW synchronised key, the alarm will think it's being nicked so will certainly go off. I would have thought that the immobiliser might have kicked in though? Perhaps if the key is in the ignition, that switches it off.
Battery should be pretty simple to replace yourself I would have thought, also relatively cheap (<£10?). You'll probably have to recode the key afterwards though, if it is the same as a couple of my old cars (they weren't BMW's though), you leave the drivers door open, turn the key in the ignition to the last point before the engine fires up, then press the lock button. All doors should lock and then pop open again and the key is re-syched. (disclaimer - I may have just told you a load of bull with the re-syching bit, but it's worth a go!!!)
EDIT - Must learn to read whole thread before replying! Naefeart's already got the recoding spot on!
Edited by Jonboy_t on Monday 10th January 12:29
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