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Discussion Starter #1
My car only came with one remote. The unlock button doesent work. The lock and boot button works perfect. I was wondering if i bought another working transmitter and maybe transferring it into my key, will it work?
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There are two systems on the circuit board in the key. One is for the remote functions and the other is for the cars security system which allows the car to start and run (passive RFID). If you use another key's circuit board the transponder chip will have to be transferred from the circuit board to the new one. It would have to be de-soldered and soldered on the new one, then you risk damaging the transponder chip and the car will not start. You might be able to program a used key and use that as a remote only.
 

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Discussion Starter #3
Thanx for that. My transponder is a small separate something. It's not soldered onto the board in anyway!
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rodsfromday,
Since the transponder is not soldered to the board it sounds like you have the old (rubber button/replaceable battery) key fob and not the newer diamond key then.

Are you sure the unlock button is not working and it's not a general module problem? Watch the interior lights when pressing unlock. If the lights come on then the button is fine and it's the general module door lock relays are bad.

To answer your original question. Yes, transfering the guts from another, similar style, BMW key would work just fine. If you buy one from another country make sure the frequency is the same. The options are 315MHz or 433 MHz if I remember correctly. It'll require a quick key resync and you're good to go.
 

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Discussion Starter #5
rodsfromday,
Since the transponder is not soldered to the board it sounds like you have the old (rubber button/replaceable battery) key fob and not the newer diamond key then.

Are you sure the unlock button is not working and it's not a general module problem? Watch the interior lights when pressing unlock. If the lights come on then the button is fine and it's the general module door lock relays are bad.

To answer your original question. Yes, transfering the guts from another, similar style, BMW key would work just fine. If you buy one from another country make sure the frequency is the same. The options are 315MHz or 433 MHz if I remember correctly. It'll require a quick key resync and you're good to go.
Yes i have one of those type keys.
When i press the unlock button the lights dont even come on. I actually took it to work and had a look at the board. All seems good except the buttons have a type of black contact on the inside that makes contact with the black surface. Also when i press the lock and boot buttons, the LED with flicker but nothing happens with the unlock.
It will be senseless to buy another unit if the general module is busted!! So how do i know what frequency i am using?
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Discussion Starter #7
Rod, I had the same issue with my (non diamond) key, it locked but only unlocked on the odd occasion. Simply changed to a new (good) battery and problem solved! BTW buy a good battery not a crap brand as I tried and it still had the same issue :( Energizer (expensive but works)
Thanx i was thinking of that but i tested my battery last night and it reads 3.1V. It might drop of with the 'load' but i will look into it!! I will pick one up when i go to the 'city' in the nest few weeks!
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Discussion Starter #8
Just purchased a working second hand remote, swapped it out into my key, now i have a fully functioning remote!! Now just to get another key!!
 

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I am watching the thread and since it looks like educated people are talking I am posting a follow up question:
Can we conclude that we can reprogram the BMW E46 transponder from one car to another? My worry was that the transponder is OTP (one time programmable) and we have to buy a new transponder chip is we "transplant" electronics from one BMW to another.

If the Transponder is OTP, do you know the chip code? ...

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My understanding of the diamond shaped keys:

The battery is only for the remote functions. There are two separate circuits on the circuit board in they key.

1. Remote functions use a battery in the key and locks and unlocks doors etc... This can be easily programmed to work with your car as long as the frequency is the same (from same country I think).

2. Vehicle security system that uses passive RFID from the steering column and the EWS system. It does not use the battery inside of the key. The steering column reads the keys transponder chip and once verified it allows the car to start. It works by using two coils one in the key and one in the column. The valet key and the wallet key have the transponder and coil, but no battery or remote functions.

These two systems are totally independent except that I believe the coil also charges the battery while in the ignition.

I have read that the security system (EWS) is made with ten transponder chips and four came with the car when new. Two master keys, one Valet and one Wallet key. This leaves six available for a dealer to sell you new keys. I don’t think it’s possible or feasible to program a new transponder chip. If you have a non working master key it is possible to remove its transponder chip and transplant this to a working key, provided that the chip is functioning.

Sorry for the long winded reply, hope it makes sense, Mark
 
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