speedometer quit working today and automatic shifting was very rough, on 1999 Ford F-250 Super Duty

also abs light comes on. What is causing this? Thanks

3 answers 6 comments
agree with double for sure. poss fill a large lake
Scan test!!
rear differential speed sensor.I could fill a swimming pool with all of them that I have replaced over the years.
I thought that sensor was just for ABS, did not know it affected spedo. operation.
Good to know!
mine is doing the same thing speedometer stoped working shifted hard till the abs light came on and then shifted fine I changed the speed sensor in the rear diff. plus the connector still did it it is up a ford now they changed out the abs control moduler. but it is still doing it and its still at ford they don't know what is wrong with it
Ain't always what ya think it is for sure.... What fixes one just might not fix the next one!!!
my truck speedometer worked fine but was shifting really hard
replaced rear speed sensor and the abs light stays on and is still shifting really hard (late shifting). (before the abs light would come on and off).
what should i do next
99 f250 superduty bone stock
Have the throttle position sensor (TPS) checked for erratic signal with a scanner... or DVOM.... Have the ABS scanned also!... Good scan test is much better than 'anybody's' guess!!!
the only code that pops up is the veical speed sensor and ia have changed it out twice with luck. what would be be next step