hi, i have an 1991 e30 with bmw fitted 3t-e30 alarm which i believe is from the sigma sg-series. there is an electronic 'knocking' noise coming from the siren on an intermittant basis. kinda like the internal back up batteries are away ? does this system have them and can they be changed if it does ? any help would be much appreciated.

gibby, January 2009

hi gibby you will have to replace the siren i am afraid as the batteries in yours are now obsolete. hope this helps

subzero ice, January 2009