fumaras

hi all,
on my E39 M5 00, i have a very strange problem with the key (unlock button) to open the car (i only use 1 key, never test the second key):

The lock/unlock key button work fine but one week ago, i have a problem with it.
I use the car to go not very far from my home.
I close the car with the lock key button and i forgot a thing in the car (but a not important thing).
I press unlock with the key but not work.
I test a second time but not work.
I have no time to play with then i leave the car and after 20-30 minutes i come back and press unlock key button.
It's work fine ! (and work fine several day).

Today i make 200 kilometers, i lock the car with the key button.
2 hours after i go to the car to search a thing, the car unlock normally with the key button, and i lock the car with the lock key button.
30 minutes after i go to the car, i unlock it with the key button, all is ok.
I make 100 kilometers, i lock the car with the lock key button.
1 hour after i try to unlock the car with the key button but not work !
I try several time but not work.
I use the key directly in the driver door to unlock the car and all doors open normally.
I test to lock with the key button. it's work.
I test to unlock with the key button it's work!
I test several time to lock and unlock with key button, it's work !

Very strange, have you a idea of this problem ? (thanks)

Digi

BMWs have electrical problems, but I never heard of one as random as yours. Maybe you have a key that is going bad and needs to be replaced? Try the other key that you never use. It probably needs to be recharged in the ignition, and you may have to reset everything for the key memory, but it will be interesting to see if you get the same results.

I have heard of areas with so much interference that the key won't work. The fact that it worked and then didn't in the same area is very unusual. It still could be caused by interference in the area.

fumaras

Thank you Digi for your answer.
yes, probably the first key is going bad (or mad ).
I'll test the second key for a long time to see if i have the same problem with it but interference is also a possibility... (but for me and for the moment, i never have a problem to lock the car with the key button, it's just the unlock button and randomly)
It'll be interresting to have the second key charged to test it when the first key don't work...

PS:
I don't know if there is a possible link but my battery is not very good.
Normally it would have to be changed but i don't know if it's a good solution because the problem is that generally, i make very short distance.
A lot of on/off for few kilometers is not good for a new (or old!) battery.
When i buy the car (and when i have the first CLICK CLICK CLICK ) i try to charge it but the battery charge to 80-90% max not more (the A switch of the charger don't go totally down and i never see the green round control on the battery top cover, just black round like battery discharged).
After some day of use, i have a second CLICK CLICK CLICK ( because the first time i just think it's normal and the battery is just discharged).
I test alternator and seems well to work.
I buy a battery tender and prefer use it all the time with my old battery for the moment.
Battery tender charge it but when i see the green light my battery is at 85% to 90% max not more (see post of battery tender).
Today and tonight i make some kilometers (400 kilometers of small/very small road, motorways, town,...) with some stop less or more longer but i don't drive very fast (and baby sleep ).
At the end my battery is discharged, (battery tender charge with orange light several hours).