Key Remote Fob Replacement

[cj10jeeper]

So where did I go wrong or what did I miss? I was being kinda smart and when my X5 key stopped opening the door I got a spare key off ebay having nearly died when BM wanted £62 per half hour to check the key then £100 for the replacement. Inc tax I was looking at a good £200.

Dissected the spare and got the electornics.
Opened my old key and pulled out the electronics
Dropped the spare electronics in the old key - so now I have correct blade an new internals
Ran a programming routine and it would open an close doors, set alarm however it would not start the engine.

Is there therefore some sort of transponder linked to the specific original key electronic module?

Actually it's really just curiosity as I found the fault on my old keys electronics and with a bit of deft soldering managed to fit a new microswitch in it from the spare..and believe me it is small

Rebuilt and the job is done and works perfectly....

[NINCHS]

Thats pretty smart thinking! What does the little microswitch look like? Pics? I have some old keys from a totaled 3er and wouldnt mind tearing them up if I need to fix a key.

[cj10jeeper]

Since you ask and I happen to have the internals and camera to hand...

You can clearly see the 3 microswitches from left to right for open, lock and tailgate. Not a lot of room to solder in there.





and for completeness the other side with battery

[NINCHS]

I got you now, so you used the old broken key and just replaced the broken part from the used key you purchased! Good thinking and way to save some money.

[ikennedy]

How did you get the remotes apart? I purchased a "new" remote key from an Ebay seller in hopes of doing the same thing you describe. It seems however that both the new and old key remote halves are permanently glued together.

[cj10jeeper]

I used fine bladed hacksaw and ran it all around the lateral groove between the upper an lower halves. Just cut deep enough to cut the lip off without penetrating the internals. The keys were so well plastic bonded they would not have opened otherwise.

It was easy enought to glue the 2 haves back together and silicone the groove to make it neat.

[ikennedy]

Great. I will continue my project when I get back into town. Thanks.

[cj10jeeper]

So back to the original post does anyone have any clue on what I missed regarding the engine imobiliser????

[Zulu95]

I remember reading about a "Chip" in the key that interacts with the alarm/security devices that immobilizes the ignition. No chip/not the right chip, no start. So something on the little ccb or in the eprom links to your vehicle.
I'm sure the dealer could link it to the vehicle as they do with any new key but there goes $100 for sure!

[X5 in AK]

Great work on taking the key apart!
I've got a key with a dead battery, it starts the car, but no remote locking. Does it look like a guy could just replace that battery in the key using the procedure you described to take the key apart?