A quick followup on my issue..

well it would seem that a couple too many drops of my key cracked something in the remote.

I have some good solder gear at work, so I reworked the whole PCB in the key, and it's now working like a top..

I have replaced the battery in several of these remotes, so doing work on them is pretty straightforward now..

FWIW, if anybody has a remote with a dead battery, i'll be happy to put a new battery in cheap for you.. SIGNIFICANTLY cheaper than buying a new key (I was quoted $165 for a key from the dealer ):yikes::yikes:

I'm going thru the same process before I throw away $170 for a new "useless" key that won't start the engine. I don't think there are 2 separate circuits and the large battery will never get charged if there is not physical path between the metal part of the key and the PCB. The circuitry is isolated from the outside world. I don't see any "imbeded" chip in any part of the key. I checked for transmission of signals off the air, nothing, just when I press one of the bottoms (luck/unluck/back door). So I still wondering if that will fix my problem.

I believe you're wrong here.. there is no circuit between the rod of the key and the PCB. I've had many of these keys apart numerous times (I"m now doing battery replacement for folks and a local dealership).

The ignition assembly has an electromagnet which fires whenever the key is in and ignition set to 'run'. IN the key is a small coil/magnet assembly which in turns charges the circuit for the security assembly. This in turn fires back an electronic code to the engine. That's the extent of my knowledge on this.

There are two or three embedded circuit chips on the PCB, and any one of them could contain a bit of a signal code, enough to do the job. i don't have one handy or I'd show you (i'm at home tonight, and have my own keys closed up again). But i"m certain that at least in this instance, the information is accurate -- it does have a signal bit which is charged by the ignition and which in turn throws out a signal to the starter security circuit.

Another method to prove this is the fact that for a year after my batteries died (Before I got the nuts to figure out how to open these things), I was able to use both my own key and my wife's key to run the car, even though the battery was so dead it wouldn't open the doors. In addition, you could stick it in and it'd start, but even when running the car, the battery was too dead to lock/unlock/etc....

hope that clarifies things....

Quote."..I believe you're wrong here.. there is no circuit between the rod of the key and the PCB..." I'm just saying the same. How could any battery in the PCB be charged, or anything in between if there is not physical link?
My concern is the starting issue, not the lucking/unlucking since it is working, If you take the PCB out of the assembly(store it 5 miles away) will the core/metal still crank the starter? As far as I can observe there is not imbeded chip in the core...I still can not start the engine.

The battery in the key is recharged wirelessly... a coil in the black round part around the key hole charges up and releases causing a charge to build in a coil in the key, which charges the battery. Think of it as a small, low power version of an ignition coil. There is no physical link from the charging input to the voltage output.

And on a fully discharged BMW key it takes 48-72 hours straight to bring it back to full charge.

:iagree: Sorry if I wasn't more clear in this.. If you ever take a key apart, this coil assembly will be very obvious. It's a small rod assembly wrapped in copper wire. It produces the charge for the ignition circuit.

No, the unit will NOT start the car without the PCB. That's the nature of the security aspect. The key rod itself will only turn the ingition assembly, but the internal relays will not pass power to the starter motor unless the unlock code is produced by the security chip in the key fob.

old thread but it didn't seem to be resolved that yes QUITE in-fact there are two electronic systems in the key fob; one for the remote functions and one for the immobilizer.

The immobilizer doesn't use battery, probably similar to RFID or uses a crystal transmitter system of some type to report back a unique identifier code that must match the one in the car.

i've used my key with no battery, it will start the car. I've also tried to start the car when the key fob fell apart and it won't start, the guts are quite required.

my dad's buick would start if the key was within about 6" of the ignition (his lock cylinder self-destructed and i removed all the pins; you could turn the lock with a screw driver, but it wouldn't start without the key near the ignition, but on the seat under the wheel was close enough)

like wedge described; my key was the same; too many drops broke some solder joints loose; it only worked when i squeezed 'just right'. after re-flowing a handful of the solder pin and re-attaching the main little capacitor in the dead center at the bottom the key snapped right back to life.

Lasted a year and then wigged out; re-soldered and back-to-life however the rechargeable battery is shot so i have a non-rechargeable in there while getting the new one ordered.

I'm glad someone "corrected" the mis-information in this old thread! :thumbup:

The statement about it being impossible to use an aftermarket key is also wrong. You can buy an aftermarket key, get it cut to fit the lock, programme the car to allow it to open an close doors etc. (easy - no coding required) and also code the car to accept the key in the ignition (to start the car). This last step requires coding and like programming the remote unlock it requires you to have ALL with you when you do this programming, as all key data in the car is wiped when doing this task.

I've done this on other euro cars - its a mission but it can be done.;)

Hi guys.
I bought a spare remote fob key (an old e39 to program and use just the remote portion) and when I programmed it perfectly last night, now one of my 2 actual e53 O.E. keys stopped remote working but starts car perfectly...

as far as I know this is the first extra key I have programmed to the x5 so it should not have "kicked" another off the EWS...
anyone heard of their key stopped working remotely right after programming another key?

What your described is exactly how it is designed to work. You cannot "add on a key" you reprogram all keys at once. Any time you need to replace a key you need every key at the same time and the car forgets any old keys and learns them all fresh.

Re do what you did with all keys and you'll have them all working.

If the remote dies on an original key you can swap the guts from the spare eBay key if the 8pin chip with the imobilizer is moved over and get a replacement key that remotes and starts the car. You can even get a blank cut if needed.