anyone know what would cause this to happen? fuse? this happened suddenly...was working fine before

Thanks

 

>anyone know what would cause this to happen? fuse? this
>happened suddenly...was working fine before
>
>Thanks

A little info about your vehicle would help.

 

sorry...1999 PSD auto 3.73LS 143,000 miles all stock

Thanks

 

Ddi you try replacing the speed sensor located on top of the rear diff? It is only around 12-15 buckaroos. It gices the computer the actually road speed of the truck. Don't know if it will fix it but it's a rather cheap place to start...


<on edit>

Are you experiencing any drivability concerns?

If not, then I probably wouldn't suspect the sensor, since the computer also obtains "tuning" parameter input from it.

 

I can't remember where, but I've also read where a guy had problems with the ground strap to his dash. You might check that also.

 

>anyone know what would cause this to happen? fuse? this
>happened suddenly...was working fine before
>
>Thanks


first thing, check all fuses. inspect all light and repair if needed.
I had a 94 f150 that this happen to and the problem was the third brake light/cargo light just above the rear glass. when the factory installed the light a wire was pinched between the light housing and the metal body and grounded out. If the speed sensor was out I think that your service light should be on. Check your owners manual to see what other devices that maybe involved with the speedo circuit.
good luck
over and out
gseeders

 

>If the speed sensor was out I think that your service light should be on.

Most of the time the light does not illuminate for the speed sensor.

Checking all the electrical connections is a great idea!

 

Thanks for all the ideas...I didn't think they were all interconnected but this all began after the batteries were drained...after charging the batteries, the service engine light,abs came on and the overdrive light began flashing... after driving the truck awhile, I then noticed the speedo and odo were not working...I was trying to tackle on problem at a time...I should have given all this info before

Thanks

 

How did you charge the batteries? I hope you didn't somehow get a voltage spike and zap the ECU. You might try disconnecting the batteries for a few hours to reset the ECU and go from there.

 

Where is the ECU? Can you describe what it looks like? How much to replace? Is it easy to swap?
Thanks

 

 

my dads 1999 did that when it was fairly new it was probably in 2000 but would have had about 50000 mi and i cant remember what it was but i think thaqt it was a common problem. they told him it would probably be recalled but i dont know if it ever was

 

I vote for the speed sensor.

 

Abs light, overdrive light flashing, no speedo, all common syptoms of a bad speed sensor. As stated before less then $20 from Ford and about a five minute job to remove and replace. I would start there before chasing electrical gremlins.