it means the overdrive is not on.
"Over Drive Off"
a malfuntion has been detected
There is a problem with the Overdrive. Seek professional help.
A malfunction has been detected
od light is the overdrive unit on the transmission. If you drive on the freeway you should have the overdrive unit on, on the streets the unit should be off. The light usually doesn't have anything to do with overheating. I would look for some other issue.
I have a 2002 F350 and my OD light came on, that was 3 transmissions ago... by default the fords are in OD, you have to turn it off when towing. Never tow without turning the OD off first. My experience was that the trans was burned up, and the light kept flashing, or You might be exceeding the speed for being in OD.
od light flashing on 1997 mercury montoneer
That's the overdrive off light
overdrive off
OD= Overdrive. There will be a switch to engage/disengage the OD located on the shifter, or on the console in close proximity to the shift lever. It should even have a marking on it.
The od light means that the over-drive is off. Pushing the little button on the shifter selector will turn it on (when the dummy light is not on) and off (when the dummy light is lit).