Freelander 2 (LR2) Dash failure when braking.

My daughter and her fiancée have a 2010 Freelander TD4.
On Saturday it started to flash up loads of warning lights and the dash would occasionally loose power completely, with the instruments shutting down.
I put a code reader on it and got a number of low voltage codes, as well as a few relating to glow plugs etc. I cleared all of these with no problem. There was one relating to a clutch solenoid problem in the auto 'box but I couldn't clear this.
I checked the battery and it was down to 12.09 volts, with the engine running it was about 14.5 volts.
She took it to a garage today and they confirmed that the battery was on the way out and fitted a new one.
Unfortunately the fault is still there and it seems to happen when the brake pedal is pressed.
Anyone have any ideas? Is there a known problem with the brake light wiring on Freelanders of this age?

when you press the brake pedal then it is lighting up the brake lights all three therefor taking a lot of your battery, I would suspect a bad connection somewhere it does not have to be behind the dash but could be, has it been check with a multi meter for voltage , I can understand the garage thinking it might be the battery as it is same sort of thing, you really need an auto electrician if you are not capable.

IME, multiple faults of this nature are often caused by earth faults - I.E. there is no earth return for a given circuit, so the circuit tries to find a path to earth via an easy route - like through other circuits. If the brake lights are not earthed properly, then this could be your problem - start simple and work up. Of course it could be a massive ECU failure - but if you can read and clear faults then this is unlikely.

Your battery voltage doesn't sound too bad - and in any event, voltage is no indication of battery state. voltage drop under high load would be, but a static voltage check is more or less useless.

Just fixed an L322 "with a duff battery" - except it wasn't - it was the (standard) knackered final stage resistor draining it - a full charge off the vehicle, a new resistor pack... and bobs my auntie.. or something like that

I had something similar with a 2 year old Octavia and it was a bad connection in the fuse box area. I had called the AA out as it was a company car and he discovered where the problem was by pushing down hard on the fuse box. If I recall it took Skoda over a week to fix it properly as waiting for parts.