Why does my speedometer needle occasionally drifts while idling

I have a 2002 Taurus SES with vulcan engine. Occasionally when idling at a stop light my speedometer needle will begin to drift between 0 and 15 mph or so. As soon as I give it gas to take off it's fine again. Is this a sign of some problem or just a random non-issue event?

Is your check engine light on?

Does your cruise control work reliably?

-Rod

CEL does not come on. Last I used cruise control it was fine, but I don't use it very frequently. I'll check it out. This happens very infrequently, maybe I'll notice it 1/month or less. Other than that the car seems to be running fine. I thought last time that I noticed the idle a bit rough when it was doing it, but it could have been my imagination.

It's just one of those wierd things. Doesn't appear to cause me any problems that I can see, but on the other hand makes me wonder if it's a sign of some future problem. Overall it's been a great car.

Tried the cruise control and it operates properly.

Does the needle just drift slowly or does it jump? Also, check the battery connections and make sure they are clean and tight.

You also may want to have the battery load tested. A weak battery can cause all kinds of strange issues on modern cars. At idle, the alternator output is low. You may want to try putting the car in park and taking your foot off the brake pedal sometime when it acts up and see what happens. If the drifting stops, then I would definitely suspect a charging system issue. If not, try revving the engine a bit and see if that has an effect. A weak battery/charging system would help explain the roughness that you think you've experienced a couple of times.

If you can in no way tie the battery or charging system to the issue, then you may have a grounding problem in the instrument cluster, but I would expect that to cause the needle to jump rather than drift.

-Rod

I just replaced the battery a month ago and it did it before and after. I suspect you are correct, that its a grounding issue somewhere in instrument cluster. At this point in time I'll leave it. It may be an occasional intermittant problem that never gets worse. In any event an intermittant ground would be nearly impossible to find. I'll see if it eventually opens permanently. It is by the way not a sudden movement, but more of a slight drift up and down until I give it gas and it goes away. Thanks for the comments.

Rod is lying he doesn't have the heart to tell you that Henry Ford(who was heavy into satanism and voodoo before his death) embeds a portion of his soul into every car. Shoddy maintenance or bad habits anger him causing his tortured soul to be invoked.....


I am serious this a know fact, why do you think Gigolos always died in Pinto explosions in the 70s and 80s and Crown Victorias in the 90s? They were good cars the rear-end explosions were just bad karma, I drove a Ford Pinto around for about 8 years and it never exploded but I was a good person and kind to my car...........yeah I am probably going to hell.....


Anyways, does anybody know if the speedometer on the Taurus is digital or analog?

Anyways, does anybody know if the speedometer on the Taurus is digital or analog?
I assume by this you mean electronic or mechanical. According to the service manual, the speedometer in the 2002 is electronic (no mechanical cable driving it).

"Speedometer/Odometer The speedometer and odometer provide speed information based on a speed/rpm pulse signal from the powertrain control module (PCM)."

-Rod

Ha, I owned a 1980 Pinto Runabout. Of course I was protected though by the plastic shield that was strapped to the gas tank. List of Fords I've owned:
80 Pinto, 86 Tempo (car from hell), 95 Sable, 94 Windstar (minivan from hell, Ford liked this one so much they bought it back from me), 2001 Windstar and 2002 Taurus. The late model cars are infinitely better than their older stuff. I've driven the new Fusion, and if I were in the market, would be very interested in the V6 model, but I digress..