Hi I have an au falcon in what I presume is limp mode it's just a standard 6 futura series 2, she's in 3rd gear constant there no other forward gears available, so far I've tried testing battery which came up good this was replaced 6 months ago, have had a second transmission put in with no change I have used forscan lite available on Android and got the code P0748 line pressure control electrical at first I thought maybe the shift solenoid konked out but having another trans in with same issue makes me think otherwise, I'm not a professional mechanic but like to get my hands dirty and have done a fair bit of works to falcons, does anyone have any ideas what this could be
Also occasionally when shifted to park or neutral there's a bad buzzing noise ( hard to explain) coming from the transmission, I've tried new fluid also, any help is greatly appreciated