Key fob battery replacement issues!

[anonymous-user]

Ive got a 2002 e46 and cant seem to open the damn thing to replace a battery. Is it just brute force or am i missing something? It seems a clamshell design with two pieces of plastic and then 3 buttons on top. Ive been trying to prise the case apart rather than remove the buttons on the top - is this right?

[john_p]

http://forum.e46fanatics.com/showthread.php?t=4515...

[Craigwww]

You can't replace them and they are charged from the ignition.

[anonymous-user]

superb thanks for that

[Sticks.]

When I had an E46 one of the keys appeared to be completely dead, flat battery I thought. Took it to the dealer and they reprogrammed it, something like this and it worked fine. http://www.programyourkeys.com/BMW_3-Series_Key_Re...

[john_p]

Yeah definitely try re-pairing them first, it looks a bit brutal opening it up to replace the battery!

If it's a key that's not been used in a while, try using it to drive the car, and then re-pairing it after a few hours of use. I rescued one of mine this way.

[Sticks.]

Oddly, both my Z4 keys failed today in quick succession. I fixed one with stage one of the reprogramming instructions (see above) but didn't hold for 15s, just took it out and held the unlock while pressing the lock button 3x then released both. Got 2nd key working by immediately holding its unlock and pressing lock button 3x and released both. Car locked and ulocked after both stages.

Anyone know why they lose connection in the first place?

[dave144]

I had the same problem with one of mine. The key will split in two with a scalpel but is sealed. To be honest the job was a real pain in the arse as when you get to the board, the battery terminals are soldered in place. The battery can be bought off fleabay but you then need to solder the old terminals onto the new battery, like I said unless you can be arsed i'd go to the dealers and get dry humped for the £100 they charge for a new one.

[Sticks.]

dave144 said:

I had the same problem with one of mine. The key will split in two with a scalpel but is sealed. To be honest the job was a real pain in the arse as when you get to the board, the battery terminals are soldered in place. The battery can be bought off fleabay but you then need to solder the old terminals onto the new battery, like I said unless you can be arsed i'd go to the dealers and get dry humped for the £100 they charge for a new one.

Did you try reprogramming it first? Mine acted every bit like a flat battery.

[dave144]

Tried it a few times with no luck, opening the key was a last resort

[Sticks.]

Being reasonably plesed with myself for fixing this, as above, it's now failed again. If I re-initialise them, it's fine, but a few uses later, back as it was. Does anyone know why it should keep failing? Unlikely to be battery as both keys work/don't work at the same time.