Intermittent fluctuating RPM's

2006 CHEVROLET SILVERADO
255,000 MILES • 6.0L • V8 • 2WD • AUTOMATIC
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MAINTTECH0625
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I have the truck listed above 2500 HD. The truck idles like normal and runs normal, but intermittently the RPM gauge on the cluster will read 0-100 rpm's. No codes have shown up. This just started a few weeks ago. What do I need to check to remedy this? Cluster, TPS? Any info would be greatly appreciated.
Oct 21, 2020 at 5:28 PM
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KASEKENNY
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I am attaching the testing that we need to run through. More then likely this is a connection issue at the cluster or the cluster itself. Your tachometer runs off of a message from the PCM so it is not like there is a cable or speed sensor that could be faulty. The PCM gets the engine speed from the crank sensor and send it to the cluster to display.

If the truck runs fine then I suspect it is just a cluster issue that is showing up on the gauge.

Let's run through this testing when it is acting up and then go from there. Unfortunately you will need a scan tool that can see the RPM.
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Oct 21, 2020 at 6:01 PM