OK guys, here is a brain teaser fro you. Driving down the hiway at 60mph, towing the 5th wheel, and on hour 7 of the drive. 10 miles from the house the speedo goes from 60 to 40 then back to 60, but truck does not slow down, and at the same time the ABS light comes on. Get to the house, turn off the truck, light comes back on, shut down, and restart the light stays off. What the hell is up with that?

 

Sounds to me like the truck is pissed at you for ending your trip.

 

My buddies 05 used to do this randomly. It eventually just stopped doing it. A lot of times it's simple, you can just remove the sensor on the top of the rear-end housing, and clean it up. Really easy to get to and do. It is magnetic and collects the little metal shavings from the rear diff. Try that and see what it looks like.

 

Speed sensor on top of the rear axle. I cleaned mine a few times and it never helped for long so I just replaced it a couple months ago. I think it was 90 bucks from the ford dealer. I'd change the fluid too so you can check out stuff inside and clean it all out. I've heard of people knocking teeth off of the gear it reads off of from debri in the fluid.

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And my truck use to only do it on an hour or longer drive. When I replaced the sensor it was to the point I couldn't even get a half mile down the road and the truck was going in and out of overdrive.

 

I will have to take a look at it and see what it looks like, don't have the time today, but will get to it as soon as I can.

 

My truck was doing the same thing. Replaced the speed sensor. Worked for about 5 miles. then back to flopping all over. One time I closed the door of my truck and the speedo bounced. So i tapped the dash and it did it again. So I tore into the dash and checked all the snap fittings. Worked for a few days. Took truck to FORD. the replaced the speed sensor that I just replaced. This was about 2 weeks ago. It worked great till today. Now its flopping all over again. And just a little FYI.. If the speed sensor goes. The odometer work work either. Happened in my truck. Drove about 450 miles and the odo only flipped 48 miles. One time it had completely stopped for about a week. And another time the odo was flipping miles at a rate of 3 or 4 per one mile. So IM going to unhook my speed sensor and let my warranty last forever.

 

by unhooking the speed sensor will it actually effect any of the mechanics of the truck

 

Nice... haha .. I agree with the above. my truck loves to work, work, work....

 

Only things that will be effected would be the Speedometer wont work which will make the cruise control not work. And the Odometer will not work. Ford tech told me that the Odo is connected to the Speed sensor. Thats why mine had quit working. But its a catch 22.. Cause when mine quit working it started flipping miles off really fast. Like at a rate of 4 miles per 1. Then it started flipping 10ths. I had went on a trip to teh coast with a trailer in tow. Trip total is usually about 450 miles. But my Odometer only flipped 48 miles. I even took vids with ym cell to show proof to teh Ford Tech what it was doing. Only had the truck since march and my late july I ahd put on 10k miles. Seemed very odd as I have never driven more then 13k in a whole year. So Im about 4 ot 6 k miles over what I should be at. Yet Ford wont do anything about it. So gotta find someway to monkey with the Odometer.