Yesterday taking the boat down to the lake i noticed my truck was idling up and down about a couple hundred rpm when i would accelerate and hold a constant throttle. I assumed the tc was taking a crap on me so i babied it the rest of the morning.When i got home i jumped on here and discovered it could be the ABS wheel speed sensor. So i took it out of the rearend and cleaned it up. Hooked it back up and took it down the road. After that my speedo started going goofy bouncing all over the place but it is shifting good again. So i stopped by the auto parts store and got one. Changed it in the parking lot and down the road we go. Hmmmmm....still doing the same thing, speedo going goofy. I had some chores around town to run so i went and done them and on my way back i noticed my brakes were getting really stiff and pulsating a touch. Shortly after the abs light came on. Then the O/D light began flashing. It wouldn't hardly shift without giving you whiplash. So i stumbled home and took it back out and looked at the harness and it looked like maybe the connector isn't worth a crap and will need a new harness. So i removed the end and made a homemade connector and plugged her into the sensor and took her for a test drive. Starts off great no flashing lights no whistles or alarms. On my way back to the house the abs light came back on and shortly after the O/D light did too and back into limp mode. I'm now wondering if the new sensor is prehaps bad also? Or is there anything else i can check? Any help would be greatly appreciated as it is my primary vehicle right now.

 

Oh and my truck it a 97 f350 dually. Thanks

 

Update: On my way to work as soon as i applied the brakes a few times the abs light came on and stayed on til i shut the truck off at the gas station. I also noticed til the light came on the speedo worked great and after the light came on whenever the brake pedal was pressed the speedo would go crazy, and any big bumps i hit after that would make it jump around. But at the very least it was shifting ok. I wonder if it got a defective sensor? I may take it back and try another. But when hitting bumps why would it make the speedo jump around? Bad connection? Crappy harness? Any help would be appreciated!!! Thanks in advance!

 

Check the sensor in the top of the rear end (VSS or RABS?) for corrosion, humidity, bad connection and debris. Just my 0.02

 

You can pull that sensor out and clean it off and it might help some. It's a fairly common problem on these trucks.

 

Thanks for the speedy replys. I got a pig tail with the connector from my local dealer and when i began to cut back the plastic shielding that covers the wires i seen a spot that was wore through from rubbing something on the rear end and it wore the wire almost completely into. So i spliced in there and took her down the road. Runs like it did before. Thanks for all the help fellow posters.

 

You are welcome, any time.
Glad to hear you figured out.

 

I only figured it out with direction from you guys.