Confusing wiring

[AlBundy]

Please help, novice DIY electrical work going on. I am currently in process of removing the unnecessary wiring and fuse board / split charge relay, and upgrading to a Sargent EC155 PSU and a new leisure battery. 

I am having some trouble identifying what 2 wires are doing, and need some suggestions. They run from under the dashboard, to behind the sink, which unfortunately I cant access (without damaging the interior that is). They are twin cable, red and brown, and may be either an earth cable, or they could be linking from the vehicle ignition to stop the tap working while the engine is on (these are my theories). 

I am pretty sure that one links into another earth cable, but the other links to a light on the sink (from feel, that's about as much access I have.

Neither wires are on the wiring diagram that I have, which looks like it shows everything else in the van (pretty much).

If these are wires that control the switch to the sink, I think I can cut them as the Sargent system will do that job now.

Please see photo's attached - has anyone seen this setup before and can point me in the right direction? The 

[Smiffo]

Stab in the dark.... Are they for speakers under the rear bench seat by any chance?
They look like speaker twin cable to me  

[AlBundy]

One of the wires runs to the back of the sink, I think to the small light at the back of the sink. See picture.

The other runs to what feels like a mini fuse box or junction box that is tucked under the bowl of the sink. The wiring there is all a bit of an unknown. The picture of the wires is what I can see from my phone, but not directly.

[AlBundy]

Update. One of the wires ran to a green light that came on when the tap switch is activated. No idea why it needed to run behind the dash, but it works, so not changing it.

The other was an earth cable for something behind the sink and tap switch, that works too so not changing that.

Still no idea why the need to go behind the dashboard, but it's all working, so leaving well alone.

[Robsey]

Maybe the previous owner kept driving away with the tap switched on.