Last week while driving home on the interstate I hit a bump at about 70 mph and it knocked my cruise off. I reset it and kept going and when I got ready to take my exit I tapped the brakes and let it decelerate and while doing so I noticed my speedometer dropping and rising rapidly. I noticed that everytime I decelerated this happened.

Now its gotten to the point that the hand is fluctuating nearly all the time, never above the speed I'm actually going though, and I cant set the cruise for more than a few seconds because everytime I do, the speedometer will drop soon after and knock it right back off. For the past two days while going up hill at a constant speed my speedo dropped and the rpm actually started to drop and rise for about 5 seconds, and I could feel it jumping, it didn't get too high or too low though, it fluctuated in the range of 1500-2300 rpm.

To be more clear, when the speedo fluctuates, it has no affect on my car or the actual speed im going but it seems like the rpm did.

Hopefully its a speed sensor, anybody have some advice or an educated guess on the problem?

 

if you have a 6th gen then dont be so surprised. the instrument clusters are known to go nuts

 

If the speedo wet way too high, then it is the speedo. Nothing in the cable or drive can make the needle go that high. Probably something inside the head is slightly warped, and bumpsthe needle and sendsit to the stop. You need a speedometer.

 

yeah, ive felt instabilitys in the cruise control, i dont believe their electrcial system is very solid, its the acilys heal of this car. in fact, this car along with the grand am, the impala, and a couple others are knowen to completely break down in the electrcial system or computer and not even start. youre going to have to flip a buck and have a certafied car electrician look at it, i think your cruise control unit is tied into your console, so i imagine its somwhere between those two circuits.

 

could also be the motor dying.

bbengineer:

http://www.bbengineer.com/cars/impala/store.htm

 

lets hope not :O