My '03 XC70 has a 1.5A parasitic drain which kills the battery. I'm troubleshooting it and think it may be a malfunctioning siren module, door locks, or regulator causing the problem.

I don't know how to test the regulator (the alternator checked out OK by AAA and an indy mechanic). The door locks all seem to work latching and releasing properly. That leaves the siren/alarm as the likely culprit.

If I find the problem in the siren (using an ammeter), can I just pull out the fuse, disconnecting the power to the siren and leaving the siren 'dead?' Or will doing so affect the car's computer brain?

Also, if I disconnect the battery (using the procedures on this forum) do I need a radio code (it's an HU613)? I bought the car used and don't have the code. BTW- how would I enter the radio code anyway...?

Thanks.