On my XK8 2003 I got fed up with Check rear Brake and Cruise control disabled message. So I have modified the switch.
Firstly, you don't have to fiddle from under the bonnet or hood. With your head under the brake peddle, snip the cable tie holding the cable to the metal bracket, then slacken the top 8mm bold a few turns, then using a socket remove the lower nut, and hey it all comes away. 10 mins max, and putting it back up again is only a 10 minute affair, you can do it on your own! Don't forget to disconnect the white connector.
I bought TWO single pole change over relays from Maplin and a 3mm by 4mm cylindrical magnet.
See this link on the uk forum for the pictures. I can't seem to get them on this forum in the edit.

http://www.jaguarforum.com/attachmen...6&d=1444380791
Fix brake switch using magnetic actuation

I dismantled the switch plastic actuator and drilled a small holder to sink the magnet into the side, just above a little tag poking out. Then reassembled the switch. I removed the circuit board, and de-soldered the relays, and replaced with the reed switches, carefully bending the wires to give them enough lead to be switched by the magnet during operation.
Now the connections to the board with the black wires. The outer ones are NC and the two inner ones are NO. Normally Closed, Normally open. The reeds have one lead longer than the other. One is the Normally Closed connector and the other is the Normally Open connect, so you use the shorter on one read and the longer on the other.
http://www.jaguarforum.com/attachmen...7&d=1444381373

You need to check with a meter for the correct operation, but I hope that you can see from the pictures how to do this. One read using the outer two circuit and the other using farthest and the inner position on the circuit board. Make sure the reeds are the same way round and close together so they operate at the same time. Don't forget the in the rest position, the reeds will be activated by the magnet, being released when you press the peddle.
The result is that you will never have this problem ever again, since there is no physical action, therefore no strain on the joints, and the reeds are in inert gas, so they don't burn out.
Good luck.