S.A.B = your outside sounder, a generic term for Self-actuating Bell or Self-Activating bell or the more modern Siren, not bell - Outside box.
tr = Tamper Return
bho = Bell/battery Hold Off 12v - Pos & Neg
12v is sent from the control panel to the S.A.B to charge the on board battery. (2wires)
An additional Neg voltage is sent in a full alarm condition (3rdwire)
The tr (Tamper Return) (4th wire), is a Negative voltage sent back from the S.A.B. to the control panel and is connected internally to the Anti-tamper circuit 7.
It sounds as though your problem is with the outside sounder.
Panels of today do not have a 'Global tamper' as you have with the Itec, each Circuit / Zone (call it what you will) has its own separate tamper circuit and this will indicate individually. The S.A.B. will also indicate separately.
acorn
August 2008