Parking brake warning light - or more?

[TD50below]

I have a 2005 TD5 90 that was parked up for a few months. When I got it back on the road the parking brake warning light stayed on. The parking brake is working and the brake fluid level is ok, so I borrowed a Nanocom and have found that I'm throwing a bunch of codes. Specifically 0,1) AC fan drive open, 0,3) Tacho drive open, 0,4) Gearbox/ABS drive open load, 0,5) AC clutch drive open, 4,1) AC fan drive open, 4,4) Gearbox/ABS drive drive open load, 4,5) AC clutch drive open. The truck drives and operates normally, but I can't get rid of those codes and that light won't go off.

Part of me thinks it could be the parking brake switch, part of me wonders if it's electrical (all the fuses are ok). Could it be as simple as the battery? Any insight or suggestions are much appreciated.

[landcrabmechanic]

Where are you?

[red90]

Sounds like a grounding issue. Check the main bulkhead ground.

[TD50below]

Thanks red90, that is what it's looking like. I'll do some further digging. Cheers.