Great result on buzzer John.
Don't know if you saw the discussion on the fuel tank thread, but during posts I discovered our cars have dedicated separate ground/chassis connections for the micro-processor read fuel sensor circuit as well as dedicated +12 volt feed. This to alleviate the adverse effects of minute voltage drop in the cable from other devices pulling current through a shared circuit, particularly a ground connection (one contributor was having gauge changes when sidelights turned on).
It occured to me this would have been checked by B & C but should you have any issues in the future worth bearing in mind.
First came across this on external smart alternator controllers. There were two similar gauge black ground wires and instructions stipulated they had to remain separate although could be attached to the same grounding point. Reason was one carried the full field control return current whilst the other was the battery voltage sense return carrying no current.