I have a strange problem. My 1987 240GL has recently started lighting up the yellow arrow that comes on when you click the control on the automatic transmission that prevents shifting from 3rd to 4th gear. When this happens, the light stays on in both positions of the toggle that activates that function. If I engage the fucntion I hear a buzzing sound coming from under the dash somewhere. If I click the control again the buzzing stops but the light stays on. Sometimes the car shifts fine into 4th even when the light is on and at other times it doesn't seem to be shifting. The light normally comes on when I turn on the ignition (as a test of the bulb, I think) but goes off as soon as the engine is started.But now, sometimes it goes out automatically on start up and at other times it doesn't.
Any ideas of what the problem might be? Does it sound expensive to fix? How do I troubleshoot the problem?
Thanks
John Merrimack, NH