Removing BMW alarm

Post Sun May 20, 2012 7:51 pm

I'm looking at removing the original BMW alarm from one of my cars with a view to fit to another. Is it just plug and play and will it cause anything not to work (central locking) on the car it's being removed from as that's still a runner?

Cheers
Dave

Post Mon May 21, 2012 9:20 pm

Post Mon May 21, 2012 10:55 pm

All the connections to the original alarm can be used for the new one - all should be behind the glovebox area.
If the old alarm is simply removed, the car won't run, since there will be a break in the green ignition switched 12 volts + wire to the engine loom. IF the old alarm was installed as intended, the break will be between the two pins (both plain green wires) of a plug above the glovebox, near the middle. To restore power to the engine loom, simply link these two pins together with a suitable plug fitted with a short loop of wire.
There might even be such a plug and wire tied up to the loom nearby.

Post Mon May 21, 2012 11:04 pm

If I'm fitting a after market alarm is it the same procedure as above with the bmw alarm? My touring has a BMW alarm but it has been disabled or removed, I'm not sure exactly what was done.

Post Mon May 21, 2012 11:38 pm

Brianmoooore wrote:All the connections to the original alarm can be used for the new one - all should be behind the glovebox area.
If the old alarm is simply removed, the car won't run, since there will be a break in the green ignition switched 12 volts + wire to the engine loom. IF the old alarm was installed as intended, the break will be between the two pins (both plain green wires) of a plug above the glovebox, near the middle. To restore power to the engine loom, simply link these two pins together with a suitable plug fitted with a short loop of wire.
There might even be such a plug and wire tied up to the loom nearby.

Cheers Brian, I'll have a poke about and see whether i can find one. Would any E30 without an alarm fitted have that plug fitted?

Post Mon May 21, 2012 11:45 pm

The plug is present on all E30s.
Those that were fitted with an alarm from new will usually have the spare plug with a loop of wire tied up the loom close by.

Post Mon May 21, 2012 11:49 pm

Cool, I can just take it from another car if it's not there then

Post Tue May 22, 2012 4:37 pm

It depends entirely on which alarm it has - the old GR420 analogue system or the later 3T. On both the control unit should be fitted to the upper cover panel in the glove box. To remove it, you simply follow each wire from the control unit - on older systems there may be soldering but on later ones, there will be plastic collector plugs, one for each wire. You just unplug the alarm wire and reconnect the original loom wires. There will be wires going to the door switches, the boot switch, one to the hazards etc. Analog systems have a contact switch on a bonnet slam hook next to the fusebox and 3T systems have a push button type switch (similar to a door courtesy light switch) on the slam panel at the very front.
On the 3T, the engine is immobilised twice. Firstly via the fuel pump wiring - look for the fat green and violet wire where you'll find the connections to the alarm control unit. Secondly with the black/yellow wire from the ignition switch - you'll find the connection in the glovebox area.
They really are very simple to remove.