My wipers and the tailgate wiper began operating whenever I turned on the headlights in my 240 wagon. I was convinced a switch was bad, but thanks to this forum, I was led to checking grounds. Using my trusty Bentley Manual to locate, I removed and cleaned the two headlight grounds under the hood-one on the fender behind the battery, the other behind the washer bottle, then the one on the trans tunnel to the rear of the dash brace bracket. All seemed a little bit in need, but not bad, but TAH-DAH!!...it worked. Thanks to those who took time to reply to the other post!