sounds like you have a short some where? or a bad earth..
check your earth points on the car. making shaw they are tight..
has the wiring been touched by any other people other than holden or an auto sparky?
ie has it had any aftermarket stuff put in to it? (lights, cd player, gages,neons, ect)
because some one could have taped in to the wrong wires some where causing unexplaned and weard things to happen.. like the parkers comming on when you dnt want them too.
but oversaly try the easyst things first as i said in the last blog... and if that failes call an auto sparky lol
hope it helps.. lol good luck.