I have a 1994 F-150 with a 5.0L V8.
My brakes are really tight when I first start driving, but then they go back to normal when the ABS light turns on. The whole time the speedo is going crazy.

I replaced the RABS sensor and that didn't help at all.
Just curious as to what in the world is going on.

 

reset the computer.

unhook battery for 15 minutes or more

 

Cool...
it's unplugged as we speak.
Hope it works

 

Speedo going crazy, as in needle bounces all over the place? If so it's probably the PSOM (if you do a search there is tons of info in here on the PSOM). That doesn't explain your brake problem though... don't know what to tell you on that one.

 

Yeah it just bounces in a 20 mph range of how fast I'm actually going...
I don't like these kind of problems...

 

The battery thing didn't work...
My brakes are a lil better but the Speedo is still epileptic...

 

Don't quote me on this, but I believe there are two more speed sesnros, one on each front wheel. I would give them a check out.

 

that is not right, no front sensors.

the psom on the back of the speedo is the next thing to suspect.

 

Nope. If anything they would be ABS sensors.
You need to swap your PSOM- its the little computer behind the speedo that takes the signal from your RABS sensor and sends it to the speedo- it also sends a signal to the PCM. It's a pretty easy swap, just find a new cluster from a truck the same model year as yours and swap them. If you don't have a tach, now is the time to find a tach cluster and swap it in (no additional wiring needed). The bad thing is that the PSOM stores the mileage, so how ever many miles the donor rig had will now show on your truck. You can get clusters for about $50 or less. When I swapped to the tach cluster in my 95 because of a PSOM problem I paid more ($125 shipped) because I found one within 200 miles of what my truck actually had.

 

Are you sure about that? Everthing I've seen says the two front wheels each have an ABS speed sensor. A 01' F-250 I saw the other day had a wire running to each hub too. It makes sense too if you think about it, how is the ABS computer supposed to know if the tires are locking it up if there is only one speed sensor

 

Well if it's the same as my '90 it only has rear ABS Beautiful thing about the '90 is it still has a mechanical Speedo

If the brakes don't get better after swapping the PSOM you may have a vaccum leak in the booster.

Oh could also be a short, I'd chase the wires first before spending money.

 

RABS still needs to know how fast the front tires are going

But yeah, thats a good point that the booster could be shot, you may also some how got some air in the lines.

 

we are not talking about an '01 are we?

this series has no sensor on any of the wheels.

it has only one sensor that reads the revs of the ring gear.

 

So thats how the mileage on my truck got off...... interesting. Either way my ABS light still comes on every now and then. But your Vin should tell you if you have ABS or RABS. All 91-96 for sure were all RABS. and some earlier models.

 

only broncos had 4 wheel abs.