My Speedo Has a Mind of Its Own Sometimes. - Chevy Cobalt Forum / Cobalt Reviews / Cobalt SS / Cobalt Parts
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post #1 of 4 (permalink) Old 08-20-2013, 05:51 PM Thread Starter
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My Speedo Has a Mind of Its Own Sometimes.

So I have a very intermittent problem with my speedo. It will jump all the way up to ~60 mph while at a stop, while idling, and drop back down to 0. Its only happened like 3 times in the year I've had it but I was wondering if someone might know what could cause this weirdness.

Also, probably unrelated, but sometimes when I am slowing down almost to a stop, my rpms will drop to ~500 almost stall, then go back up to the normal ~800, then drop back down to 500. It will do this about 5 times before it settles down back to normal idle. I think it happens more when it's quite cold outside.

Any ideas on things to check?


2007 Cobalt Ls Manual Coupe
Kenwood Excelon X996, RF T3 Components, RF Power 6x9s, Sundown Audio SA10, RF Power T600.4, Alpine MRP-1000, Kinetic HC-1800, Black headlights, FX-R HID 55W, Custom led tail lights, Led reverse lights, Airbox mod.
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post #2 of 4 (permalink) Old 08-25-2013, 10:16 AM
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I had the issues like you have with the RPMs. I cleaned my throttle body and the decrease in RPM stopped.

As for the speedo, I have that issue randomly after I shut off the car, the needle will jump. My guess is a stray current somewhere. Maybe a loose ground, or a worn through wire.
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post #3 of 4 (permalink) Old 08-25-2013, 11:38 AM
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^^ The speedo twitching after shut off
is perfectly normal for these cars...
they all do it.

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post #4 of 4 (permalink) Old 08-28-2013, 09:03 PM Thread Starter
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Mine does it while it's running, and it's not a twitch, it's almost a half sweep of the needle.


2007 Cobalt Ls Manual Coupe
Kenwood Excelon X996, RF T3 Components, RF Power 6x9s, Sundown Audio SA10, RF Power T600.4, Alpine MRP-1000, Kinetic HC-1800, Black headlights, FX-R HID 55W, Custom led tail lights, Led reverse lights, Airbox mod.
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