electrical mayhem

Got home from work today only to find that I couldn't remote-lock it, got back in & restarted the car, & checked stuff, with the engine running the headlights & rear lights permanently on (lightswitch has no effect) rear windows work, but not the fronts,suspension goes from mid to high, but not to low, no rear wipe or wash, fronts work, but wont park, no interior lights, tailgate button works, but nothing locks via the remote, & only the front door locks with the key. Tried hooking it up to my Rovacom, but it won't talk to the BECM, but the Rovacom WILL talk to the Diesel ECU!!
It has a new hi power battery, & starts readily, had ALL fuses & relays out, all seem ok, earths seem ok as well, I feel it points to the BECM, any ideas??

too many faults at once to be BeCM! recheck earths, disconnect battery for 5 mins and try again! maybe lucky, i had similar!

Thanks for that, but i'm petrified of disconnecting the battery, when I fitted a new one last year, I connected a small 12 alarm batt & a couple of test-leads to the car, simply to keep the electronics 'alive', with my luck, I wont be able to re-sync the fob to the car & be in even more trouble!

The car has bags of 'oompf, I starts easily, even with the headlights full-on, so the earths must be ok, also, I hooked up an extra battery to the main car pos, & the neg jump-lead to the engine, so it had a different earth connection, still the same.
BTW, every write-up I read says that the BCEM is under the LEFT seat, mine is under the RIGHT seat, with the fuse-door as well, under the left seat is the suspension & gearbox ecu's.

Just put a meter accross the big-main fuses & they ALL show that they are constantly 'live' with over 12v, is that correct?