Volvo Anti theft alarm Relay controller Up for sale is a volvo anti theft alarm controller relay. Fully functional. This device performs a variety of functions in relation to the theft alarm and a faulty unit can cause a whole host of strange problems. Part number on this relay is 91 28 903 (9128903) / 89 8757 000 (898757000) . this is also a good part to keep as an extra, as it can go bad at any time! they are well over $100 at the dealer... Thanks for looking