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Speedometer Fluctuation with 2007 Chevy Impala

Hi Everyone,

My 2007 Chevy Impala has developed a brand new problem today. Driving down the block to the store, the speedometer started fluctuating wildly. I was going a consistent speed of about 10 mph in my parking lot and when I braked to a stop the speedometer started swinging all over the place, from 10 to 35 mph. It then gave me a message on the dash saying “Speed Limited to 107 MPH” and somehow killed my accelerator because the gas pedal no longer did anything. I restarted the car and the accelerator worked again for a bit and then pulled the same problem again. The speedometer is now fluctuating wildly the entire time I drive, including while stopped, but so far the message seems to have kicked on and disabled my accelerator only when slowing to a stop and accelerating out of a stop (it happened three times).

I know that the Impala’s governor is set to 107 mph so I can guess why that message exists, but I wouldn’t think a governor would actually kill the car even if it kicked in at the right speed.

It wasn’t that long ago that we had to have our pedal position sensor resynchronized and the mechanic had mentioned that it was possible the sensor was going bad, but I don’t think that would be the problem here as it seems like the car would actually have been accelerating sporadically, whereas in my case just the speedometer is swinging around despite an even speed.

Any thoughts on what the problem is here or how much it might cost?

My first thought would be excessive ripple from the alternator. Unplug the alternator so it’s not charging and see if that fixes your problem.

Did you figure out what was wrong with your car? My car is doing the same exact thing.

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It seems like other people have asked about this same problem in other threads, not for this car in particular but in general. The most common reason seems to be the speedo’s actuator is faulty. Motorized gadget. Part of the instrument cluster.

You do realize you can buy the actuator motors separately . . . :smiley:

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