What in the world is wrong?????

My 1999 Mercury Sable has some problems. When I am driving..usually highway speeds.. The speedometer will start to bounce around,the o/d off light starts flashing,and then the service engine light comes on. When the speedometer is bouncing around the car kinda cuts in and out. I am now driving it with the servicing engine light on and so far no problems....Any ideas what I should do/look at. One mechanic hooked it up to the computer and it said it was a problem with the cruise control,however the last time it happened the cruise was not on. Lastly, If you shut the car off and start going again it runs fine for 15-20 miles then starts all over again. Any ideas PLEASE help.


Craig

Could you get the mechanic to tell you which code(s) came up? Then post 'em here? AutoZone will read the codes for you, too. If you have an AutoZone handy.

Would it be a problem related to the engine finally getting warmed up? Where is the temperature guage running?

Temp is running normal at all times

Your mechanic may be right. All these things are interconnected. You most likely have an electronic speedo (there is no cable). You do need to know the code to fix it.

You problem is most likely the VehicleSpeedSensor, (VSS), which is located in the transaxle.
I had the same problem with an older Taurus. It would shift in iand out of OD and the speedo would jump all over the place. The part was about $30 and it fixed my problems.

You problem is most likely the VehicleSpeedSensor, (VSS), which is located in the transaxle.
I had the same problem with an older Taurus. It would shift in iand out of OD and the speedo would jump all over the place. The part was about $30 and it fixed my problems.

I got to this forum by Googling for that exact problem in my 99 Taurus -- it happened for the first time tonite: speedo went all erratic, the "O/D Off" light flashing, but no "service engine soon" light.

So here it is several months after your post... is your Taurus still behaving? I'd really like to believe that a cheap part could save me a lot of grief!

I got to this forum by Googling for that exact problem in my 99 Taurus -- it happened for the first time tonite: speedo went all erratic, the "O/D Off" light flashing, but no "service engine soon" light.

So here it is several months after your post... is your Taurus still behaving? I'd really like to believe that a cheap part could save me a lot of grief!

Paul,
Actually the Taurus was sold and is still working fine, this post was about my 99 Sable, which is still working fine after changing the VSS.
It's a pain to get at if you don't have the car up on a lift.
I jacked it up and it took me about 10 minutes to find it because it is covered with a piece of insulation to keep the heat from the exhaust pipe from toasting the VSS. The insulation has some tin foil like covering on it.
The angle you have to work from is kind of difficult unless you can get the car up on a lift. Good luck.