So my 95 f150 has been having a problem where the speedometer starts jumping around at higher speeds, the engine starts running rough, and the check engine light comes on. After some research, I figure that this is the vehicle speed sensor. My only problem is that all of the auto part stores list two vehicle speed sensors. I found the one on the rear differential, but where is the other one? I bought both just in case. It is an XL, 5spd Manual Trans, 6cyl motor. Thanks for any help.

 

So further research is showing me that the auto parts store may have given me the wrong part. I got the right part for the sensor on the rear differential housing, but I think the second sensor they gave me was for an Auto transmission vehicle. There is a sensor on the tail cone by the rear drive shaft, but the part on my truck looks nothing like the part the store gave me.

This is the sensor on the tailcone that looks like the one on my truck:
http://shop.advanceautoparts.com/p/d...=speed+sensor#

This is the sensor the part store gave me:
http://shop.advanceautoparts.com/p/c...=speed+sensor#

does the sensor the parts store gave me go anywhere, or is it the wrong one?

 

One on the diff, one on the trans. Looks like they may have given you the wrong part. Change the diff sensor anyway, that's usually the first one to act up, you may not need the other one.
Sometimes you just have to clean the diff sensor (and change your fluid) but if you're replacing it, general concensus is MOTORCRAFT ONLY.

 

I found this for Jeeps as well. I have been a jeep owner for 10 years, and when ever a sensor goes, the only ones that work well are MOPAR. If I bought aftermarket sensors, they were always messed up. I feel like Motorcraft is to Ford as MOPAR is to Chrysler/dodge/Jeep. I found a Motorcraft sensor for about 30 bucks on Amazon, ordered it today so I should be able to install it in a week or so. I will post how things work out. I will change both sensors to be safe, they aren't too expensive.

 

So after a long process of troubleshooting, I found out that my model truck actually only has one speed sensor. The Vehicle speed is determined only by the sensor in the rear Diff. I changed the sensor, and the problem didn't get any better. After more research....The only other possibility was the PSOM (little computer behind the spedometer). I changed it and problem was solved. I found this link from another thread about the issue for changing the PSOM. It was really helpful:

http://www.harleyhummerclub.org/PSOM/index.html