Another key fob activation thread

[elm1304]

Hello all,

First post here! Have bought a 2005 Z5 2.0 coupe - really loving the car, it's in a wonderful condition and everything works well - fixed the roof motor that was already transferred in the boot so it was an easy job.

Now onto key fobs..... The car came with two keys, one that works perfectly (works = all buttons work and they what they should) and one with (I think) had a dead battery. I proceeded to change the battery in the second keyfob and knocked out a couple of components (read the warning about delicate opening only after)....

I proceeded to buy a cheap 433Mhz diamond key from Amazon, charged the battery, got it cut, and ran into issues trying to program the fob.... let me explain.

I try all 3 pairing methods with the working key, and the car responds as I expect it to (locks shoot up and down). When I try any of the methods with the new key (standalone or immediately after programming the working key), the car doesn't respond, zilsh, nada, nothing... and obviously the buttons do not work.

I am a little bit stumped because as a diagnosis, I think:
- GM5, wiring loom, locking mechanisms all work (as evidence by the good key getting a response)
- I triple checked the new key and the old key are on the same 433Mhz frequency
- the only thing i can think of is that the Amazon key is speaking a different language???? or that the car doesn't go into programming mode and just humours me with the locking/unlocking sequence

Does anyone have experience with those cheap keys and maybe any recommendations?

[Rockhopper]

Can't help you I'm afraid but I've never heard of anyone using an Amazon or non BMW key on their car.

[colb]

I bought an ebay Chinese key blank had the blade cut by a old style cobblers and key cutting shop then had to get a mobile locksmith to programme the transponder in the key to the EWS system, that was the costly bit. Original key and new key then paired to the car using the finger dance procedure which worked fine. The keys have to be synced immediately after each other so they work ok. Both keys have been working fine.

[enuff_zed]

As Colb suggests, if you haven't done anything with the transponder then it won't work. Needs to match the EWS.

[elm1304]

ok ok, that's interesting because I have to admit, I ignored the transponder bit for now as I (wrongly?) assumed the transponder and fob part worked independently of each other... but maybe that's where I am going wrong!

[colb]

There are two separate systems in a key, the battery only supplies power to the central locking functions within the key and has no connection to the transponder chip that is also inside the key fob. The transponder is read by the aerial that is around the ignition barrel and speaks to the cars EWS module, if the code in the transponder matches with the EWS module it releases the starter and fuel delivery so the car can start. The transponder has the fixed code and the car also gives it a rolling code each time the key is used so both codes have to match when read the next time the key is used. The central locking function inside the fob is all contained on the small pcb in the fob that has the key battery and the buttons on it. An uncoded key fob (transponder) will not star the car however the central locking function system in the key should be able to be set using the finger dance methods.

[elm1304]

That's what I had assumed as well so - in theory at least - the (Amazon) key fob I have should be able to be programmed via finger dance.... mystery remains.... have ordered a new one and will test that (in case I have a dudd), I can always return it if it doesn't work...

[elm1304]

For posterity, if anyone ever comes across this problem, the first Amazon key didn't work, the second worked.... from what I gather the PCB with the antenna that loops around the edge WORKS, the one with the visible coil DOES NOT WORK. Of course, it could just be my car.