I have noticed that the over-drive dash light (up arrow) in my 87 740 automatic sometimes becomes 1/2 or dimly illuminated. If I press the shift lever switch it fully illuminates and the trans downshifts if it is in 4th. Pressing the switch several times usually causes the light to go off completely. There doesn't seem to be anything unusual with the way the trans is functioning. Does a 1/2 illuminated light mean anything (I don't have an owner's manual)?
RHL