I bought a truck. 1993 f150 4x4.

Speedometer doesnt work, odometer doesnt tick abs light is on and shift rather hard, the overdrive off light is not on or blinking.

-I bought a new vss on the rear end. Installed, and no change.

-I then checked all the fuses and swapped a different one in for the #18 just incase it was broke and I couldnt see it. Still no change.

- I then pulled the abs controller out from behind the glove box, still no change,( re-installed)

-I then perform a speedo test(?) Where you push the reset button and turn the key forward and the needle runs all the way up and then back down. (it isnt exactly a smooth motion on the way up, but its not really noticeable)

- I then realize the previous owner had unplugged the warning buzzer under the dash, Plug it in and still no change.

What is my next move? Push it in the ditch? Thanks for the help.

 

"Bad wiring in my opinion"

Check that wire that goes from that Sensor all the way down to were it stops. Run a new one if you have to.

Speedometer broke and needs to be replaced.

For the hard shifting problem that is probably that sensor you replaced, but since you have bad wiring most likely coming from that sensor it will not fix the problem. I replaced that VSS sensor in my truck and made the problem worse for me. I just stuck the original one back in and kept going. I think I have a bad speedometer on mine.

I'd recommend checking to see if you have any error codes. You can do a self test, buy or borrow a reader from most major parts stores.

Fuel Injection Technical Library » How To Run a Self-Test

 

Did more reading......about 3hours worth

Im gonna pull the 4wabs module from my old truck, and 96 that got wrecked, and trade it for mine, and see if that fixes it.

Ill let you know how it goes.

 

The VSS sensor on the rear end very seldom goes bad, everybody changes it but that only makes thing worse or no help with the problem. If it has junk stuck to it and you do not break it taking it out then you can try wiping it off and that some times works for a while but that means you have rear end problems.

If you unplugged the RABS module and that did not help then changing it out with another truck will not help either. It is out of the system with it unplugged.

You more than likely have a bad rear end with bad bearings and that is letting the gap be too wide between the tone ring and the VSS. But check the wiring first between the VSS and the RABS plug. This is twisted wiring so replacing with a wiring that is not twisted may not work either.

The Speedometer head and Odometer are more than likely OK. You may have a problem with the PSOM that the Speedometer head and Odometer plug into. If it is holding the VSS generated AC voltage down that could be your problem also. Try unplugging the PSOM and plug the RABS module back in and see if the rabs light is still on. If it goes out you have a bad PSOM.

 

Hey subford,

I didnt get to read the post you made until now.

What I did today was. Took the gauge cluster out of a truck. (I was driving the parts truck until it was totaled, I drove it to the body shop and to my shop, so I know the speedo and odo works on it)

Took the parts truck cluster, and put into the new truck. and nothing changed.(put stock one back in)

I check the wiring for the vss. I put a lead from my ohmeter on the red/pink and the lightgreen/black wire at the rabs plug, and got no resistance reading. And went from those two wire to a ground and got no reading.
I got those wire from this post of yours.
https://www.ford-trucks.com/forums/1...ml#post9537130


What is next? replace the wires to the vss?

At all costs I do not want to replace the speedo-odo, because this truck has 23,800 miles and its a 93!!!

 

Sounds like you have a open in the wiring from the RABS plug to the rear end speed sensor (VSS).
A 1993 should have the same wiring as the 1992 for the speed sensor, the VSS is called a DSS in the diagram below:


/

 

OH YEAH!!!!!! (kool-aid man style)

Thanks subford, I started to trace the wires this morning, about 3 foot of wire from the vss right by the rear shock, was a red and pink wire out side of the loom, well I pulled on it, and it came out. So I dug into the loom pulled out the other end, soldered them together. Now Im back in the hunt.