My 1984 volvo 240 has electric overdrive controlled by the button on the 4 speed shifter. It once was operational (no problems) shortly after purchasing the car 4 years ago. At that time, an overdrive relay was installed by my mechanic and everything worked great. Currently, the demon has a mind of its own. It chooses to go into overdrive "whenever". Typically after cruising at highway speeds for a while. It sometimes "tries" to shift at around town speeds. Very disconcerting for your car to "seem" (at least it feels like) it's going into a higher gear at speeds of 20 or 30 mph. In frustration, I removed the OD relay but the problem persists. Could the transmission fluid be dirty or need topping up? If so, how do I proceed?
