2006 XKR 38,000 mi. The symptoms were no ACC and nothing in the window. After different lengths of time the check rear lights would come. Then sometimes everything was fine and then it got worse. So following the advice on this forum I started eliminating things. Discovered the check rear lights came on when only the brake lights came on. Took both light bulb modules out and did the cleaning and all. Buy the way I don't believe you need English light bulbs. Make sure they are the right replacements, 1157 and 1156 but also make sure they are the right wattage, this is stamped on the bulb and near the light socket on the board where it goes. No Luck. Next stop light switch. I ponied up the money at the dealer $153.00. Changed the switch by the forum recommendations, taking out the drivers seat is a must and two people can do it. Use a pad on the brake peddle and push it all the way with your head. Both problems fixed.
Thanks to this forum for all the ideas. This saved me about $600.00 or more at the dealer.