The Australian market generally uses its own version of the European connectors, as well as its uniquely own contacts.

[1][2] The only connector used on the Australian market that is fully ISO standard conformant is the 7-pin ABS / EBS plug.

Pin 2 (54G) is in the Australian wiring standard the reversing light, which is a minor problem.

This means that you can connect a trailer with a 5-pin connector to a 7-pin socket or the other way around, but since the pins are wired in a different way the result may be far from what was expected.

Auxiliary power, breakaway sense or hydraulic brake pump should never be wired to pin 2, even if the trailer does not feature reverse lights.