First, THANKS for all the info here that helped confirm my repair needs!

I just replaced the Output Speed Sensor on my transmission. ('05, F150, 4.6, automatic, RWD) MY speedometer was VERY erratic: sometimes dropping to 0 and then popping back to 70 mph. Also, my transmission would slip into neutral at highway speed: less often, it would not engage after sitting at a stop light. When the tranny would act up, I would put it in park and restart the engine, then it would run fine...sometimes for days, thereafter. Lately, though, it was happening every 15-30 mile.

I just replaced the OSS, plugged in a code reader and drove 60 miles with no issues!

 

That's great!

 

Thought I had this fixed, but it did again! The speedometer became erratic, and the transmission slipped into gear from dead stop a couple times. The transmission never went into neutral at highway speed during this 60 mile trip, just slipped going into first like you were slowly releasing a clutch. The tranny problems only happen when the speedo is acting up.

Any suggestions?

('05, F150, 4.6, automatic, RWD)