No probs mate.
Right... If you look behind the brake pedal you will see a white plastic tube about half way up with an electrical multi plug in the back of it. That's the brake pedal switch. It's secured in a metal frame.
You remove it by giving it a quarter turn while pressing the plunger that usually rests against the brake pedal leg. It may be stiff as it might have been in a while but it will twist.
Disconnect the plug and take it in the house where you can safely disassemble it without losing bits.
You will notice two little plastic lugs on either side. Press them in with a small screwdriver and prise the end cap off gently. Pay attention to what comes out in order. Iirc it's the plunger, a spring and then the contact head.
Borrow the wife's emery board that she files her nails with...(shhh, she will never know)
You will notice two small contacts that look like pin heads about 1.5 mm across in size each. They will look black but believe it or not they are actually copper. Give them a quick rub with the emery board, easy does it, just until they are shiny and then fit it altogether in order. give the plunger a quick spray of lubricant and refit back into its slot and twist... But don't forget to plug in the connector first, I didn't the first time and took me a lot of fumbling followed by a face plant moment when I realized I just wasted ten minutes when I could have plugged it in first
.. Job done and easily very DIY
For some reason even though the brake lights still illuminate as normal if these contacts are dirty they throw up plenty of brake fault codes...
I can only assume it's a high resistance reading across the contacts that throw the ecu off kilter a little, yet brake lights just need a voltage signal with less resistance.
if you are still have issues then it's time to investigate further at more expensive items but I would certainly try the most logical and free fixes first..... They often are the that simple.
That's assuming the wife doesn't catch you using her nail care products on the car.... then it's the most expensive fix in the world, if you get what I mean....
Most dealers and Indies will just replace them as the are about £ 12-15.... But I'm a tight 4rse and see no point replacing a serviceable item