1997 F150 XLT 4X4, 4.6 automatic, floor shift transfer case. bone stock

I am getting the P0720 code, "output shaft speed sensor circuit". Speedometer is also acting crazy, it shows maxed out at over 100 while actually going 30 mph. below 30 it drops smoothly according to speed, just very high reading. (10mph reads about 40 for example).... VSS reading with scan tool shows the same speed as the speedometer. i have the 4R70W transmission (door code "U"). i have already replaced the sensor on the output shaft of the transfer case as well as the one on the side of the transmission. i have not replaced the ABS speed sensor on the rear axle, but have read that the 4R70W uses this for the speedometer. but why would i be getting a code the output shaft speed sensor and not getting any codes for the ABS speed sensor, nor an ABS light? transmission shifts fine for the most part. somewhat hard at times, and occasionally slow to shift. but with 200k+ miles.........I dont expect it to shift perfectly.

 

The rear sensor (ABS) is the sensor the for VSS with 4R70W transmissions.. I'd change that out. That helped my 98 straighten out the speedometer. My 98 has a E40D with the VSS on the side, and that wasn't the problem. The rear checked out ok, but I had another rear end, so i swapped the sensor. Damn thing started working correctly. Researching it out, It reads the rear ABS ring for information.

97-98 have problems with the cluster also. THere is a small motor, which runs the gears to the odometer. If the gears wear they do all sorts of weird crap. The stepper motors are a soldered ribbon group. If you should need anything inside your cluster, PM me. I have 4 torn down sitting in a pile. All are tach/speedo type. 1 cluster is perfect, so I won't disassemble that. I have the clear plastic holder that breaks also, if necessary.

 

Usually when this code appears, it is also accompanied by a flashing OD Off light on the end of the shifter. Is that flashing as well? Doesn't matter either way, that sensor needs replaced. Don't be surprised if it is coated with little metal chunks when you pull it out.