Which module are you thinking of ?
On our 2007 C5 I disconnected the alarm siren to check on a battery going flat problem, but made no difference. I then disconnected the alarm module and with the engine running the indicators flashed all the time but again did not help with the battery going flat. The siren is located in the left side of the boot in the wheel arch area and to remove it needs the boot left side lining removing and that side of the bumper releasing. The module is located in the left pillar area and needs the glove box removing to get to it.