CAR 42ZC entitles pilots to carry out maintenance on class B aircraft as per CAR schedule 7 & 8.
Schedule 7 lists what a pilot may not do including;
Part 4 Maintenance on electrical, instrument and radio systems
4.1 Maintenance of operational software and automatic test equipment software;
Schedule 6 also applies as it states the requirement to record all maintenance carried out on an aircraft in either the aircraft log book or aircraft documents (MR).
And finally this from the CAAP 179A-1(1)
GPS navigation database maintenance;
Quality control of the navigation database extends to the
maintenance activity associated with updating the database.
For some equipment types procedures are relatively
straightforward, however others may involve maintenance
that may only be undertaken by pilots with a maintenance
authority issued by CASA. CASA can provide more
information on the requirements applicable to particular avionics on request.