E36 alarm wont disarm Urgent help needed.

[beefy]

Hi calling on some help please.

The story goes i have gone away for the weekend. Went to drive car this afternoon and the alarm wont disarm. I got in the car with the key and the alarm went off but the car started. So the battery is fine. The remote is ok as the led lights when i press the button and its bright so battery in that seems fine.

The problem must be with the alarm unit in the car but what and where the problem is i dont know.

Its a standard factory fit bmw alarm and the car is a p reg 328i sport.

I need to sort this asap as i need to drive it home 2moro. Any ideas?

[beefy]

I also dont have the key with me to turn the siren off at the back of the unit.

[B7]

Sounds like the fob has become alien to the code on the car. Had EXACTLY this fault on the convertible I'm selling at the mo.

1. Do you have the 5 (maybe 6) digit code in the history? If you have that the dealer can disarm it using the code and then reprogramme the remote. It can only be recoded if the system is in disarmed state.
2. If you don't have the code, BMW will tell you your f*cked! New unit needed as it cannot be disarmed in order to recode the remote! Works out about 400 quid if I remember correctly. HOWEVER, I have heard that virtually all dealers have a spare unit with matching remote. They replace the coding unit (its a seperate slot in part on the end of the main unit) in your car with their spare. They then disarm the unit. They then put your coding unit back in and recode the remote now that the alarm is in disarmed state. Apparently loads of technicieans have a spare 3g coding unit in their tool kits. You just need to find one.

You can disconnect the system and still use the car. I did it on mine. get your tools ready though and warn your neighbours. The unit is behind the glovebox. Strip the glove box out and locate the alarm unit (you'll see the seperate slot in bit at this point). Heres where I get a bit wooly. I can't remember which wires you need to disconnect but I seem to remember it was fairly obvious. If i found it the I'm sure you can. You should then be able to drive the car to the dealers. It was surprisingly easy to "hijack" the system really.

Good luck

[beefy]

Thanks B7 for the thorough and quick response.

I went to disconnect the alarm after warning the neighbours. Went under the bonnet with the alarm going off to stuff a rag in front of it to quiten it down a bit. Unplugged the siren to see if it went off but obviously didnt so just plugged it back in.

Got ready to pull the glove box out and thought ill try one last time. And it worked why i dont know? The only change i made was the unpluging and plugging it back in but cant see how that will of affected it.

[B7]

Good news. Ours got corrupted (we think) by the mother in laws Micra's alarm. Somehow the BMW picked up the same frequency.