I know this problem has been brought up on many occasions but I have not found a post that is identical to my own issue. 2003 ex v10 4x4 with 148000 miles.

A year ago, I had an issue after rain, mostly. Rough idle, od flashing, truck dies and service eng light comes on. Was told the mas would get moisture and that is why the problem would go away after 5 mins of driving. Problem went away for 9 months until a few weeks ago.

Had a bad u joint so I replaced it. It has been bad for a while. I assumed there was just play in the tailshaft so it seemed. When the u joint got real bad, the sensor issue came up again. This time I had it checked because the check eng light stayed on.

After u joint was fixed, truck would not stay running. As soon as you put in gear the od flashes and the check engine light comes on, truck dies also at stop lights. So I checked the sensor in the diff and it was really dirty. I cleaned the sensor and the truck seemed fine for one day. Sure enough, the parts guy at Ford said to change all the sensors. I recently had to change the alternator and battery so I figured maybe the sensors went bad. After changing them, there is no change.

The truck won't even leave the drive way. I start it and when you hit reverse, it dies. Same old story. Cleaned connectors and not sure where to go from here.

Question, why did cleaning the sensor in the diff help for a few days, then not help at all? Is there a relation since this seemed to be the culprit? I know some folks have been through hell with same issue and if there is anything new on this issue, I would be very thankful. I am really in a desperate situation with this truck being my work vehicle.

Thanks, Billy

 

I don't see why you looked at the sensor in the diff if you have a P0720. That code is for the sensor on top of the trans at the rear of the trans, not the one on the diff.

If you have replaced that sensor (it's called the OSS - Output Speed Sensor) you need to investigate the wiring between the OSS and the PCM. Most likely there is some damage or corrosion. You'll need to check it electrically, not just visually.

 

Thank you Mark,

I will certainly do that. I spoke to an old friend that said these wires are prone to cracking. I will get a new pigtail, also.

I bought an extra sensor for the front of the trans. Should I replace that one, also? If this code has no relation to that sensor, I assume leave it alone.

I hope this will fix this issue. I remember when vehicles were so much easier to work on. My 1st car was a 70 Torino GT. Good times-good times.......

 

P0720 only relates to the OSS on the rear of the trans. No other sensor is involved.