Was pulling my 5th wheel back from the mountains at 65mph,on interstate,I have a 6sp stick,so on long uphill grades,I"ll push the off button on the cc and downshift to "hi"(1 to 1) then back to OD and 6th and hit the cc,when I did that,the speedo went to "0" then back up to "65" about 3 times,then the ABS light came on.Truck runs fine,ran great all the way home,but integral trailer brake wasn't working right after that,if you shut truck off and restart,ABS light will stay out for about 10 seconds then come back on,I disconnected battery when I got home and reconnected,didn't help,I know a lot of Fords run the speedo off the excitor ring and pickup in the rear end,(I have a rear end shop),I checked wire going to pickup,seems fine,truck only has 40,000mi,any ideas? I've got a buddy with a shop and all the code readers,that's probably next,any help would be appreciated,Thank,Jack

 

Mine did the same thing. Noticed the speedo would drop every once in awhile and then the ABS light started coming on. Replaced the rear speed sensor and never had the problem come back. Easy fix, one bolt and the sensor comes out. Has an o-ring seal, so no gaskets or sealer to deal with either.