Exactly what it says on the tin...
you have a tamper problem. Either a cable has been damaged, a detector cover is loose, or the outside sounder has become insecure against the wall.
All cables to door contacts or detectors in an older/basic intruder alarm system contain two seperate cores which are your tamper circuit. This circuit is active even when the alarm is unset. If broken during the unset time then a local alarm will sound (internal sounder). If the external sounder is going then the problem is with that. Newer systems have a single circuit comprising the circuit and the tamper. It relies on resistors. If the circuit is complete then a certain resistance is seen by the panel, if circuit broken (tamper) then a different resistance is seen.
Bill T, November 2010
