Transmission Overdrive

I have a 1997 Ford Explorer XLT control trac 4WD that is driving me crazy. When Im driving between 35 to 45 mph the transmission does not shift into overdrive. Then the over drive off (OD off) indicator starts flashing on and off indicating that the over drive is turned off. It will not go into over drive even when I get to higher speeds. But, when I park the vehicle and let it get cold, start it back up, let it run until it gets warm again the over drive turns back on and the transmission shifts perfectly. As soon as I slow down to between 35 and 45 mph and stay at that speed for a short period of time, say two minutes, it happens again. If Iam not accelerating or decelerating the OD OFF indicator will start flashing again and the over drive turns off and stays off until the vehicle gets cold. I have changed the transmission fluid and filter and it still does this.


Can anyone tell me what the problem could possibly be?

I don’t know if the auto parts store’s scanners are enhanced to pull transmission codes, but start there. Most do it for free. If they can’t pull tranny codes, then the vehicle has to taken to be someone who can.


Here’s another case of you should have read your owner’s manual.
A flashing over-drive light does not mean overdrive is off, a steady OD light means over-drive is off.
The owner’s manual says that a flashing OD off light means that there is a problem detected with the transmission and that you need to have it serviced ASAP as the fault may be causing more damage to the transmission.

It must indicate that the over drive is off because it will not go into over drive once it comes on. I have serviced the transmission.

Tester is right; the tranny computer is recording a trouble code when the light is flashing. The computer is also going into a “failsafe” mode (because of the trouble code)and locking you out of overdrive. You need to have the tranny computer scanned to see what the trouble code is.

I did have the ECM computer scanned the code was throttle position sensor. It was replaced but it did it again. Does the transmission have a seperate computer that can be scanned?

Yes, it would seem so. Or the scan tool wasn’t enhanced to enable it to get a transmission code. Seems like a strange way to do business to me.

Have a trans shop scan the computer with a real scanner. That flashing O/D light is just trying to tell you something.



"It must indicate that the over drive is off because it will not go into over drive once it comes on. I have serviced the transmission."
Solid on means the overdrive is off.
Flashing means there is a transmission fault. This fault is preventing the overdrive (and who knows what else) from working. A failed overdrive and an off overdrive are two different things.

It takes a Ford specific scan tool to read the transmission fault codes on your Explorer.