2008 Ford Ranger flashing O/D light

Three days ago while driving around 35 mph I noticed my truck was having trouble switching gears–the tachometer was revving but the speed was not increasing and the truck started to feel a heavy drag. I gave a little gas and it eventually shifted up appropriately but then started to severely drag again and the O/D light started to flash on the dash. I pulled over immediately with what little power the truck was putting out and turned the car off. My owner’s manual said to get the transmission serviced or risk damage. I took it to my mechanic and he couldn’t find anything wrong with it, kept it for four days and said it was fine and that they couldn’t recreate the problem and couldn’t find the solution. He also said that the computer was reading a code for a “5th gear incorrect ratio”. He said that I could take it home and that it would probably happen again and that I should take it to a trans shop the next time.
My question is, am I going to severely damage the truck if I keep driving it and wait for something to go wrong again or should I immediately take it in to the trans mechanic? And has anyone else experienced this problem with their Ford or know what this problem could be? I wanted to get some input before I take it to the trans shop and spend a lot of dollars trying to diagnose a problem my mechanic couldn’t find. Thank you for the help!

The lock up torque converter clutch may be slipping. When the OD light is on the transmission may be in limp mode and locked into 3d gear whenever shifted to drive. I would suggest servicing the transmission immediately.

Also, the computer won’t recognize the input to output speed deviation until the engine is fully warmed up and a series of prerequisites are recognized. Your mechanic may not have driven long enough or fast enough to duplicate the problem.

The ‘5th gear incorrect ratio’ code indicates that the transmission recognized that there slippage. If the light starts flashing again, stop, allow the transmission to cool, and limp home using 3rd or 4th manual gear selection.

If the fluid level has been okey and is okey, have the transmission technician do a line pressure check – especially when in 5th gear.

Thanks for all the feedback! I picked up my truck from the transmission tech yesterday. Unfortunately he said he couldn’t figure out the problem. His mechanics couldn’t duplicate it and didn’t pick up any codes that would affect the transmission. They cleared the codes and drove it numerous times and nothing came up. He said my transmission fluid looked really clean and not at all like the fluid of a car suffering transmission problems. So I have the truck back but was cautioned that I would probably be back in when the problem shows up again. Is this something I need to be very worried about or should I just boil it down to gear slippage and assume that the car is fine? After going to both my mechanic and the transmission guy I don’t quite know what more to do. Thanks

If it were mine I would drop the pan, replace the filter, refill with the proper fluid and add bottle of Trans-Medic… And hope for the best.

A flashing OD light on a Ford can be caused by a faulty speed sensor so it might not be a bad idea to check into that. In theory a fault code should be set; in practice it may not be.

I have a 2000 ranger and as i was coming home last night at a speed of 65 i hit a bump on the freeway and then i felt a clunk, thats when i saw the o/d light flashing so i try to get over to the shoulder,( people don’t listen to a blinker) and by the time i get over I’m doing 35 then as i pull off the freeway I’m doing 15. And after i shut the truck off i see some smoke! What can this be. Oh and now i have to take wife’s car to work.

@Celticman, you should start your own separate thread and when you report the issue report full info on the truck - such as mileage and maintenance history, especially that related to the transmission. And you’ll want to be a bit more descriptive - smoke? From where? Look and smell? How much? Then what? Towed home dead in the driveway? Did you pop the hood and look? Check the trans fluid? …