I have a 2002 Ford Ranger 4.0 2WD and automatic transmission. A couple of times recently my overdrive off light has come on. First time I turned it off. Second time it wouldn't allow me to turn it off but the next time I started it the light was off.
Any suggestions?

 

OD OFF light will flash if computer has set transmission OBD2 codes

The OD off button on the shifter is not an on/off button, its a momentary contact switch
When pressed it sends 12volts to the computer and computer "toggles" the OD status, i.e. if OD was on then its turns OD off, if OD was off it turns OD on, so each time the button is pressed the status of OD is switched on or off
When computer is restarted, key off and then on again, OD is set as ON so OD OFF light will be off on startup every time

There are 2 wires inside the metal shifter arm for the button, they exit the arm under the Clam shell cover on steering column and plug into a connector
The 2 wires can chaff where they exit the metal arm, if the 2 wires short momentarily its the same as pressing the button, so OD OFF light comes on, and then can go off all on its own if they sort again

With key on all the dash bulbs should light up, this is a BULB TEST to tell you if any bulbs are burned out, so OD OFF light should come on with the test but then go off a stay off unless you press the button

 

Thanks for all your help. Mine isn't flashing it just come on for no reason. Based on your information I guess I need to check the wiring under the clamp shell. Is this something I can easily replace?

 

You can get new shifter arm with boot like this: https://i.ebayimg.com/images/g/k4IAA...q3/s-l1200.jpg
About $70

But you should also test current wire first to see if it has a short
After clam shell is off start the truck, then watch the OD OFF light while you move that wire around, pull on it and twist it to see if light comes on
And push the button a few times to make sure light is working like it should