Voltage Dropping

[Simsy2323]

OK, for some time ive had an issue with my car, started off with the engine light (been to holden and no codes show), then the airbag light comes on, I lose my fuel injection metre which sits at 0 when the problem comes, the problem comes and goes, but when it starts i get the littlecross on my aircon display screen, and my overspeed display, and if i turn my lights on i lose my taco, or sometimes just winding the window down causes voltage drop and i lose my taco.

Ive replaced the alternator because apperantly that was playing up, yet my battery keeps dieing still.

so, is something drawing all the voltage or am i not getting enough voltage and need to replace the battery now? loose wires or anything? any tips will do,

Its a VX Berlina 2000

[db_notso]

check battery terminals are tight
check under rhf kick panel (near your feet under dash) check if earth under here is tight

if not these you need an auto electrician... or someone on hand to find the bad earth
too many systems are being affected for it to be something small or an ecu so is probably a cheap fix at least