BMW 320i SE key fob problems

Troglodyte

Hi, I'm having a bit of trouble with the the key fob for my '95 BMW 320. Recently, I dropped the keys, and the cap for the batteries fell off, causing the batteries to fall out. I put them back in and screwed on the cap. However, when I tried to remotely unlock the doors, there was simply no response. The range hadn't exactly been great recently, so I thought the batteries were simply clapped out. I bought new batteries, inserted them, and the key fob still won't work.

Does anyone here have any ideas as to what could be wrong? I'd be pretty relieved if this is a fairly simple problem to fix, as I've heard that key fobs can be pretty damn expensive to replace.

Thanks.

I've attached a few pictures of the key fob.

Anan1

Fors starters, I don't think that remote is a BMW one. Have a look under your bonnet, you should be able to see what make of alarm you have. Some remotes need a particular sequence of buttons pressed after changing the battery. Once you have the make & model of alarm, you could probably find this using google. If that doesn't work, i'd say the next stop would be to find a supplier for your make of alarm.

Andrewf20

Look thoroughly at the fob PCB, and watch for dry joints - where the solder may have cracked creating an open circuit. Old electonics can suffer from this.

JHMEG

That's a Sigma AC38 fob, which can be had on ebay for less than £15 (any more is too much).

You will need to get your alarm programmed to accept the fob. How that works depends on the model of alarm:
a) If you have a 10-digit keypad in the car, you need to enter (I think with the ignition turned on):
*17856 - The siren will Bleep
*91 - This is the programme code to programme radio keys
*X - This requires a value between 1 & 4 depending on how many radio keys you require to programme
# - The siren will bleep and you will now need to press each radio key in turn waiting for the confirmation bleep after each remote press

b) If you don't have the keypad, you need to get someone with an Sigma alarm programmer. Sorry, can't help you there.

[BTW, I'm not a Sigma specialist or anything of the sort.. I know the above because I bought and fitted a Sigma M4 to my Integra]

Troglodyte

Thanks for the replies. As regards getting my alarm reprogrammed, I don't have that 10-digit keypad, so that's out. Also, I clumsily managed to lose my spare set of keys a couple of months ago, so I can't gain entry to the car without the alarm going off, nor can I deactivate the immobiliser. This seems to make reprogramming impossible. Any ideas?

JHMEG

There is someone in Ireland who does Sigma alarms, I just can't remember who. A guick google turned up nothing, but I didn't search very hard.

If the installer was the guy above he usually puts a bypass switch somewhere in the car, usually under the dash. See if you can find that. It's a small toggle switch taped onto the end of a couple of black wires.

Your only alternative is to locate the alarm unit itself by following the cable from the siren. You can unplug the unit from the loom, but you will need to find where the immobiliser wires are patched in and "undo" them, and connect back up what ever they immobilise, ie ignition switch or fuel pump.