Just had a new transmission installed Monday,now my over drive light is blinking and emmission light is on.Stopped at Auto Zone they checked the code and said it was 720 speed sensor.It has 36/36 warranty guess I will take it back to Ford dealer Friday.It is a 2002 heavy duty 5.4 l crew cab.Don't under stand the emmission light being on thought someone might have had this problem before.

 

Search? Replace speed sensor. Light will go out.

 

I have the same problem, replaced the sensor, light still flashes, and the speedo doesnt work. I did replace the batteries, is there a reset switch?

 

Maybe the exciter(tone) ring in the rear.

 

Hi,

I have a 02 F250 Diesel with 33,000 miles, yesterday on the way back from Troy, NC my overdrive light starts blinking, everything else appears to be fine. I stopped the truck removed the key and restarted and the light went off, after a short period it came back on again. Any ideas were to start? Where's the speed sensor? My Speedo appears to be working ok.

 

I had Ford dealer repair mine because of the warranty.My problem was the Pcm had to be replaced.There are two speed sensors one on the rear and one on top of the transmission.I would take it to Auto Zone first and get a code.

 

Hello.
The OD light blinking is almost always on due to rear end speed sensor failier. If you get a CK engine light on at the same time it may be the sensor in the tranny or the internal sensors are picking up internal slippage. The are several conditions that can cause this.

 

My OD light was blinking because the throttle body in the transmision was bad.

 

I've got the same problem. Rebuilt tranny installed and a flashing OD light. The light will only flash when I am in Park, though. Once it is shifted to Drive it quits. My Mech. says he can't get a code from it. Also, I was looking around the tranny tonite and noticed a vacuum fitting on the transfer case near, what I am guessing is the electronic 4wheel shifter. There is no hose on this fitting. The fitting has the clean/dirty line on it which tells me there was a hose on it at one time. Does anyone know?

'99 F250 SD PSD automatic

 

If you can get a pic of where it is I'll go under and look for you.

 

This forum is Great! Thanks for all the info, I dropped my truck of at Dale Jerrat Ford today (warranty)
I will jump in again when the problem is fixed.
Hope all are having a great labor day weekend

 

I don't have a digital camera, sorry. Heck, we just got that there internet thingee on computers here Nebraska. Ha. Here's a better description. If you roll under the drivers side on your creeper and look on top of where the tranny meets the transfer case. It's about three to four inches back, darn near straight up from the electrical hookup on the transfer case. I'm guessing it's a 3/8" fitting that elbows up then toward the motor.

 

There is supposed to be a hose. It runs forward then into the engin bay. I can not follow it to where it goes. My guess it that it is the vaccume hose for the auto hubs. If you don't have ESOF then you might not have a hose but that would IMO need to be plugged? You should see the hose if there was one it is pretty long. Hope that helps.

 

F350 PS V8 Diesel CC.

My overdrive light started flashing and I took it in for diaognostics. They said it was the transmission solenoid. The part cost me about $215.

Gin

 

The OD light in my 2001 expedition started flashing. Dealer had to replace the transmission... under warranty thank god.