Great info thanks -sure beats hard-wiring in a new bdi and horn haha

remove and inspect power contactor for terminal overheating. if terminal cooks,will melt into cap and tips will not make good contact. bdi will read empty and unit will engage lift interupt indicated by horn beep when lift buttons pressed. controller power supplied by separate wire at pos terminal input on power contactor if ac unit or ptc if pmc unit.

Thanks Mankymitts -the connector looks like new still but I haven't had the panel off to check the BDI. Battery voltage is correct and passes load test ok so yah it probably is the bdi or controller.

the horn sounding is the controller sensing that the battery is flat. maybe the BDI is faulty or the connector has come adrift.i,ve seen this happen when a truck is getting a lot of oppertunity charging. have the battery checked out fully also..