Well I thought I had it. My O/D started to blink again, as soon as you start to drive. Out of nowhere my Check Engine light came on at the same time I noticed my speedo, odometer, and trip didn't work at all. I've replaced the VSS twice to no avail. The code that was pulled from the CEL was PO500, VSS fault/malfunction. I can't seem to figure out why 2 new sensors dont help solve this.

Can anyone help me out?

 

My 2000 F150 had the same thing happen over 2 years ago and the speed control sensor on the transmission was bad. Check the electrical leads on your transmission; it may have fallen off the speed sensor.

jeff

 

Check the speed sensor on the rear differential. Measure the resistance across it if you've got a multimeter, it should be something like 1000-1800 ohms if I remember right, most times when they fail, they show infinite resistance.

 

Hey 97f150f/s, is your truck a 4x4? If so you should be looking at the speed sensor that mounts in the extension housing of the transfer case. The one in the rear diff is for the abs on your year of truck.

Did you check the condition of the plastic gear inside the transfer case where the vss goes. I have seen many that are loose(erratic signal) and worn down (no signal). Many times when the gear is loose it will cause codes intermitantly but not all the time.

It sounds like your vss drive gear is worn down/damaged.


Hope this helps
Cya

 

xplorer, thats what I was kinda thinking. That it might be shot inside. How can I fix that? I mean i replaced the sensor 3 times and still nothing works. Tranny shifts fine and drives fine. Its just that dam CEL and OD light. I have a multimeter so i'll check them again.

 

Ok i just took the vss off again and checked inside the whole that it goes in. I didn't feel anything inside that would be similar to the pink speedo gear or to make it move. Its all smooth inside. I did however feel something move or fall out of the way and can't touch it anymore. Is there something similar to the speedo gear inside the tail shaft?

 

If you reach in the vss hole, you should feel the vss drive gear. It goes around the output shaft and is a larger gear than the one on the vss.

If you cannot feel it or its that loose on the shaft, you are going to have to remove the transfer case extension housing (it is a 4x4 right?) If its a 2wd it is a different set up.

On the 4x4 you have to remove the rear driveshaft, then the six(?) bolts on the extension housing and tap the housing with a deadblow hammer to loosen the silicone seal. After that the vss drive gear is obvious.

The original gears get loose or swell on the shaft because of water contamination in the transfer case. So you should drain and refill it at the same time. Your transfer case has the plastic little hockey stick looking vent, if so get rid of it and run a piece of hose up to the top of the trans.

This doesn't apply of course if your truck is a 2wd.

Post back what you find
Cya

 

The gear that drives the VSS gear is built into the output shaft. Here's a picture of an output shaft, the spiral cut gears are the ones that spin the VSS gear. It's highly unlikely that they are damaged becuase they are steel and the VSS gear is plastic.

 

pheww, thats helps alot. Thanks for that pic.


But I still dont get why i can't get it to work.

 

Disconnect the VSS harness (VSS should be located near the rear section of the transmission).

With the engine key ON (engine not running) check the VSS harness voltage. It should read 5 volts.

If it does not have around 5 volts then have the PCM checked out by the dealer.

 

Hi guys, not trying to cause a problem, but LEPEW's picture is similar to what a 2wd 4r70w output shaft looks like.The picture looks like a 700r4/4l60e shaft.

The output shaft in the transfer case for a f150 has a removable plastic drive gear for the vss that mounts on the shaft.
The 2wd shaft has the vss drive gear cast into the shaft the same as the picture. Your truck is a 4wd or 2wd?

I have replaced way too many of these drive gears on 4x4's to count, that's why I was saying if the truck is a 2wd it is a different setup.

I am not saying that this is the problem, but it is very common.

Just my .02

Later

 

my bad guys. Mines the 4x4. Since you said there is a plastic gear on the shaft. Im wondering if thats what i felt move and couldnt feel it anymore.

Be honest with me. Is this something i could takle myself or should ford do it?

 

Good call Xplorer, I'm a 2wd guy myself.

And you're right about the output shaft too, it's some type of GM unit. I posted it because the VSS drive gear is shown clearly.

 

Well it turned out to be a $2 part inside the tail housing. Completely sheared away. Thats why my speedo didn't work. But my O/D still comes on. So im ordering the speed sensor for the rear axle and going to replace that one and the vss in the tranny tomorrow.

 

So you will do it yourself? Let us know if it is easy to do.