Hey guys so I just bought my 2000 Ford excursion 5.4l with 87k miles. Got it for cheap because of this issue excursions seem to be plauged by. Read in one of the forums it could be the alternator so I tested it and sure enough it was bad. Replaced the alternator and everything seems to run great no more sputtering hard shifts etc all seems to be well. Only issue is OD light continues to flash after a few minutes and it still is giving me the p0720 code, now the guy I bought it from said he replaced the oss on the differential and changed the trans fluid. He also said he didn't see any metal shavings or gunk in the pan, lastly all the coil packs are brand new and I know there's always a possibility he could have replaced the sensor incorrectly or broke something but aside from that does anyone have any ideas how to fix this or what it could be ? Has anyone else experienced the same issue ? Any information would be greatly appreciated. And the alternator was just changed tonight and I took it on a 15 min drive stopped turned it off and started it again to see if the issue would return as off now no problems everything is running better than when I bought it hopefully this stays resolved

 

There is no OSS (Output Speed Sensor) on the differential. There is a VSS (Vehicle Speed Sensor,) but you don't have a code for that. The P0720 code is for the OSS, and that is on the output shaft side of the transmission, on the top. Since your problem seems to be intermittent I suspect the problem is a damaged wire between the PCM and the OSS.

 

Ok I will have to check that I drove it around all day today zero issues no rough idle hard shifting sputtering or anything changing the alternator seems to have fixed the issue I'm wondering if the guy who attempted to fix it prior messed something up when the problem was the alternator the whole time. The problems have went away but the flashing OD light and code still remain I'll get under the truck today and search for issues I'll let you know what I find

 

It's been a while, but when my '02 had the P0720, I replaced the OSS (at the output of the transmission). Also replaced the spark plugs and coils, just because it was time...but somewhere in all that, the P0720 was cleared and has not returned.