Faulty Tach Reading

Having posted here before on Chevy truck issues, I was hoping I could get some information regarding my 2004 Chevy Impala. The other night I was traveling on the interstate at about 70 MPH. The tach was reading about

2100 RPM. A short while later I noticed that the indicator needle had fallen to about the 5 o'clock position. The indicator still seemed to try to track RPM, but it certainly wasn't in the proper position on the guage. The cruise control continued to work fine, and there were no sudden surges or anything like that. I've used the car several times since then, the needle is always in the 3 to7 o'clock position and does move with RPM fluctuations. Anybody know what drives or provides the tach signal these days? Or is this more likely to be a faulty instrument panel cluster? All other gauges are working properly. Any thoughts would be appreciated. The factory warranty has expired. I need to research if this is something that the extended warranty would possibly cover. Thanks!
Reply to
Gary Picha
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My 2003 TrailBlazer tach does the same thing. Eventually it resets itself. Don't know what causes it but I think it's mechanical and not the signal being sent to it because in my case at least, the tach stays stuck even with the ignition off.

Reply to
Meat Plow

I think your tach and speedometer are stepper motor type. Watch the needles when you turn on the key. If they drive down to zero and then bounce up, I'm right. Look on ebay for "gm stepper motor" and you'll find them.

Al

Reply to
Big Al

I think all the gauges are steppers. They all make the same noise, kind of like water trickling when the ignition is turned on and the zero.

Reply to
Meat Plow

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