Bad speedometer in '04 Impala?

Hello all,

Wondering if anyone can help me.

This summer, my wife drove my car for an errand. When she came home, she said, “What’s wrong with your speedometer? It’s reading like 20 mph faster than you’re driving!” I went out to the driveway and sure enough, the needle was stuck on 20, even though the engine was off and the car still. I got in, started it, and the needle went down to 10. Gauge showed about 10 mph faster as I drove (ballpark). Did an errand, got back in the car, and the gauge (which had been at 10 when I turned the car off), went down to zero. Problem solved!

Weeks went by, and no other instance of this. I wrote it off as a fluke. I did find, though, that right about in this time, my cruise wouldn’t work. Just arbitrarily wouldn’t turn on. 90% it worked though.

Late August, we were driving on the highway, and I noticed that I was being passed by everyone. I looked down and it showed me going 90! Within 15 minutes, the needle went all the way to 120 (the max), and then beyond. I got home, turned the key, and the needle went to 0.

Took it to a mechanic near my work (not my regular guy), who suspected a bad speed sensor. He ran tests and found nothing.

The problem hadn’t occurred for months, and then started again about two weeks ago. One day, I noticed the gauge was high, and when I came to a stop, it showed 35 mph. I turned it off, turned back on, and it dropped to 25. Rinse, repeat, 15, rinse repeat, 5, rinse, repeat 0.

Took it to my normal mechanic last week, and he tested it. There has not been any Check Engine light activity, and he plugged in his machine and found no trouble codes. He did a ‘swing test’ with his machine on the gauges, and could get the fuel gauge to go to Full and then back to Empty, and then could get the Temp gauge to swing to full and then Cold, but he couldn’t get the speedometer to do anything.

He said that he’s never seen a problem like this, and is looking for a used dash cluster for me.

Any thoughts on what this could be?



The OP posted this back in January and is probably not hanging around waiting for an answer still. However, my mom’s '04 Impala with about 60k miles recently started doing the exact same thing. While she’s driving, the needle will keep creeping up until it’s lodged on the pin past 120. If you shut the car off and turn the key to aux, it will drop a little. Do it about 50 times and it’ll reset back to 0 for a week or two until it happens all over again.

I checked for TSBs and found one that could be relevent - NHTSA 10006362, which says “IPC, tachometer, speedometer, gauge needle noise. SIT bulletin 1457611.” No idea what that means.

Anyone have any brilliant ideas for me? The mechanic my parents use thought it’d be too expensive to throw parts at, so instead my mom drives the car around, sometimes uncertain just how fast she’s going. Thanks!

Is the odometer still working correctly? If so, it seems very likely that this is a problem internal to the gauge cluster. Replacement is probably the only solution.

I suspect this is turning into a trend for that model. A co-worker has the same problem. It is the actuator for the gauge and most want to replace the entire cluster to fix it.

Yes, the odometer is still working.

Thanks for the info, TwinTurbo. I’ll let her know.