After finding out I had this on my car ( thanks to this site) I tried it out, first short trip, worked great on the way there, but nothing on the way home (same roads), or since.. Until yesterday. Reading other posts believe it may be controlled by speed, as well as light. If this is the case what speed does it kick in at? I have use mostly local roads ( dark & winding) where it would of been ideal, last night traveling back from Southampton mainly on A roads it suddenly kicked in and worked