1994 Ford F-150 Speed Sensor

My speedometer/odometer (Electronic Dash) went out and now the
transmission shifts hard. I narrowed it down to the vehicle speed
sensor, but I can't find it. There is a sensor on the rear
differential, but it completely different from the new VSS I have in my
hand. I assume it is an ABS sensor. I looked on the rear of the
transmission, but couldn't find anything like it. Anybody know the
exact location of this little gem?

Thanks,
John

1994 F-150; 4.9 I6

I do believe your speedo and ABS and ECM input all come from the RABS
sensor you saw in the top of the rear diff. I would suggest that the
new VSS is for a different application. Test the output of the RABS
sensor and make sure the reluctor ring on the ring gear inside the diff
isn't loose, cracked, missing teeth bent, etc.

If you don't have ABS problems (like the ABS light on all the time)
then suspect the speedometer module that is behind the combination
meter. It gets the RABS sensor signal too, and uses it directly to
operate the speedometer, and it also produces a unique output signal to
the ECM for feul, spark and shift management.

Toyota MDT in MO

On 17 Jan 2005 13:29:23 -0800, "
> wrote:

>My speedometer/odometer (Electronic Dash) went out and now the
>transmission shifts hard. I narrowed it down to the vehicle speed
>sensor, but I can't find it. There is a sensor on the rear
>differential, but it completely different from the new VSS I have in my
>hand. I assume it is an ABS sensor. I looked on the rear of the
>transmission, but couldn't find anything like it. Anybody know the
>exact location of this little gem?
>
>Thanks,
>John
>
>1994 F-150; 4.9 I6
it is the one in the rear diff...the parts people sold you the wrong
one....the one that takes a gear, correct???
mike

Yeah, it looks nothing like the sensor on the rear differential. I've
included a link that shows it exactly:
http://www.smpcorp.com/web_app/catalog/images/SC46.jpg

-John

Well I have no idea where the 'speed sensor' goes that the parts guy
sold me, but I think I found the RABS sensor you guys were talking
about. Part #: F85Z-2L373AC

Thanks for your assistance guys!

is it not on the transmission housing?

On 19 Jan 2005 08:34:16 -0800, "John Manner" >
wrote:

>Well I have no idea where the 'speed sensor' goes that the parts guy
>sold me, but I think I found the RABS sensor you guys were talking
>about. Part #: F85Z-2L373AC
>
>Thanks for your assistance guys!

Nope, not anywhere I could see. I looked all over the transmission for
anything remotely like the sensor I bought, but couldn't find anything.
Unless it is on the very top of the case, which I doubt.

John Manner wrote:
> Nope, not anywhere I could see. I looked all over the transmission
for
> anything remotely like the sensor I bought, but couldn't find
anything.
> Unless it is on the very top of the case, which I doubt.

And you won't find it. The RABS sensor is all your truck uses. The
speedo module I was talking about previously is a PSOM, programmable
speedometer odometer module. I checked on the component name after my
last post. Its part of the instrument cluster and as far as I know
needs to be replaced as a unit if bad. The PSOM failure would explain
bad speedo and ECM/transmission control issues without an ABS problem.
You can diagnose it by checking all of the inputs to it at the cluster.
One of the PSOM functions is that it allows you to enter a number
based on a formula given in the factory shop manual of tire size, axle
ratio, etc. to calibrate the speedo based on your specific vehicle. It
can have the calibration procedure performed 6 times before it locks
you out of further calibrations.

Toyota MDT in MO

The ABS light isn't on, and it passes the start-up light up test. So
now I'm thinking I'm looking in the wrong spot because if the RABS
sensor was bad, the ABS light would be on right?