B side cab door opened by itself. TC tried to close a few times but to no avail. Unable to isolate . Passengers detrained to platform. RS and LTOC informed. ~~~~~ 3660 "B" side cab door opened by itself. Level 3 TC tried to close a few times but to no avail. Unable to isolate. Passengers detrained to platform. RS and LTOC informed. L3 3660 B/S cab door fault able to duplicate in depot. 3660 B/S Magnet switch out of alignment - Readjust. Tested Cab door operation - OK. Checked all relays for abnormalities - OK. Checked all cab door operration - OK. Kana 44398