Mine is also 2003 .You do not have a maple immobiliser at all, and so you can safely remove all of the box and wiring from under the seat, it really is very easy and you can be pretty ruthless with the snips as there is miles of wiring that you will no longer need.
Spanner Monkey; you da man! It's been bugging me for ages - last remnants of it being a commercial vehicle. Passenger seat now replaced with a captain's single with all the gubbins under that one in the bin. Now it's time for the driver's seat... now where's my snips? Thanks once again...A: Thanks for others' comments too...T:
Solid State box has now been removed with a little bit of rewiring to retain the use of the flouro lights. Haven't removed the wiring loom - too scary for me - so have bundled the wires together, sealed them into an old icecream container that has been sprayed matt black, and zip tied the box to the inside of the seat base. Nice and tidy, almost invisible, and leaves me with useful space under the seat. Before lobbing the solid state box, I removed all the fuses which I recon may come handy. Ta da!
You can do it either way but personally I removed the red anderson plug from the box which is the power supply and traced it back to the battery and removed the lot, It all depends if you have a use for yet another permanent live in your van, there are plenty to choose from in the fuse box already. I removed all of the Ex AA wiring as I dont like the idea of unused wiring hanging around in the van, if you strip your van out youll find it very easy to remove it all. if your van is an early one youll need to make sure you dont snip out the maple immobiliser though, dont know much about these as mine is a later one so Ive never seen one. hope this helpsT:
You could try pulling out the two big fuses under the bonnet near the battery as these are for the jump start solenoid and the ancilliaries so only the normal van wiring should be powered, hopefully this will stop your battery draining.