Speedometer Troubles

About 5 months ago I started noticing the speedometer on my 2004 Chevy Cavalier started acting funny. I would be driving and suddenly it would be stuck at 40 or 50 mph even after I had stopped. Initially it would reset itself but over time it would stick at higher and higher mph and is now all the way around the meter past 100 mph pointing straight down with no movement whatsoever. I’m uneasy driving without a speedometer and I’m dreading the day I get a speeding ticket. What do I do? Is this an “easy” fix or will I have to take it in and get hosed?

What year Cavalier? Is it a electronic display or mechanical?

Could be as easy as swapping out the dash unit with a salvaged dash unit with a similar mileage. Or, as easy as removing you dash unit and cleaning all the contact points with electrical contact cleaner. Very, very rarely will the wiring between the ECM and dash unit go bad to cause these issues

These dash units are all electrical. There is no mechanical connection between the speedo/odo to the transmission. They read from the VSS (vehical speed sensor) filtered through the ECM.

Thanks. I’m not sure I’m confident enough to take the dash unit out myself but I’ll take a look and see.

This is common to the 2004 Cavalier. It’s not isolated to your speedometer. Next, your fuel or temp gauge will go. Or maybe your tachometer. On my Cavalier the speedometer started acting exactly as you described way back in the summer of 2007. They’ve all died and now currently none of the gauges work. Heat somehow screws them up–heat from the sun or heat from your heater going through the vents. Anyways, I just went out and bought a Scanguage II. Plugged it into my OBD port and mounted it on the steering column.

If your tachometer still works (assuming your car has a tachometer), you can figure out the approximate speed at different rpms. WIth the automatic, this isn’t the best system, but you can make it work.

Years ago, I used to ride an intercity bus from home to my college campus. The comany was a small company and ran Flxible (yes, the spelling is corredt) bodies on GM chassis. The bus didn’t have a speedometer, but there was a tachometer and it had a different mph scale for each gear.

Do you have a smart phone? Mine is an Android. The I-Phone is another. I’m sure there are more, but those are the most popular types. If you have such a phone, there are apps available that will give you a true speed readout. Some of those also include genuine GPS with voice directions. I use a strictly MPH app as I test drive many cars weekly. I don’t trust ANY of their speedometers.