My 2005 CLK has just developed a fault with the lights. Regardless of the lighting switch position, both side and headlights come on when the car is started. The light switch works correctly when the ignition is on (ie auto, side, headlights, fog lights), but as soon as the car is started up, the lights come on regardless, even with the switch in the off position. I fitted a towbar recently, so thinking that may have upset the electrics, I disconnected it, but the problem is still there, so that doesn't seem to have been the cause. Any ideas anyone?