Thanks to several posts in this newsgroup, I was able to identify the culprit behind the overdrive light sporadically coming on, one time while driving 70 mph on the highway, resulting in a sudden drop down to
50 mph! As I know many of you know, this has to do with a faulty overdrive relay (grrrr - not only a lousy design but dangerous as well!!)Anyway the newsgroup posts allowed me to locate the overdrive relay (behind the ash tray), remove it, and pry off the cover. Several posts suggested cleaning the contacts and resoldering the joints. These looked very clean to me and I solved the problem as follows:
In the center of the circuitry, there is a small magnet coil and a small switch relay attached to a spring. The relay is normally up when power is off. When the car is normally started, the magnet is activated and the lever pulled to the down position. This seems to be what turns off the overdrive. In my case, the relay sometimes seemed to get "stuck" and did not make contact in the down position. Since I NEVER use the overdrive nor would I ever want to, I simply permanently forced the relay to stay in the down position by wedging a small piece of wood between the upper contact and the upper surface of the relay. This seems to work great and -- assuming you don't need the overdrive
-- a fairly simple way to solve the problem.
I'd be interested if anyone has either tried this same solution, or knows of a problem that could result. Hopefully this might help someone else out someday!
Mark