1. The Obvious Checks (Easiest First):
* Fuse: Check the fuse related to the instrument cluster. Your owner's manual will show you the fuse box location and diagram.
* Instrument Cluster Lights: Do *any* of the lights in the instrument cluster work (e.g., fuel gauge, RPM)? If none work, the problem is likely with the cluster itself, a fuse, or a power connection to the cluster. If some lights work but the speedometer doesn't, the problem is more likely within the speedometer mechanism itself.
* Cable (If Applicable): While less common on later models, some vehicles use a physical cable to connect the transmission to the speedometer. If your Tahoe uses a cable, inspect it for damage or disconnection. (However, the 2000 Tahoe Z71 is more likely to use a Vehicle Speed Sensor (VSS) electronic system.)
2. Electronic Issues (More Complex):
* Vehicle Speed Sensor (VSS): This is the most likely culprit in a vehicle of this year. The VSS is located near the transmission. It sends a signal to the instrument cluster. A faulty sensor will prevent the speedometer from working. You'll need to locate it (your owner's manual or online resources can help), inspect the connector for corrosion or damage, and potentially test the sensor itself using a multimeter (or have a mechanic test it).
* Instrument Cluster: A malfunctioning instrument cluster is another possibility. This could be a faulty speedometer mechanism within the cluster, a wiring issue within the cluster, or even a damaged circuit board. Replacing the entire instrument cluster is a relatively expensive repair.
* Wiring Harness: Inspect the wiring harness leading to the VSS and the instrument cluster for any breaks, chafing, or corrosion. A damaged wire in this harness could interrupt the signal.
* PCM (Powertrain Control Module): In some cases, a problem with the PCM can affect the speedometer. This is less likely, but possible. Diagnostics would be needed to confirm this.
3. Next Steps:
* Check the Owner's Manual: This will give you crucial information about fuse locations and diagrams.
* OBD-II Scanner: Use an OBD-II scanner (available at most auto parts stores) to check for any diagnostic trouble codes (DTCs). These codes can point to the specific problem.
* Professional Mechanic: If you're not comfortable working on your vehicle's electrical system, take it to a qualified mechanic. They have the tools and expertise to properly diagnose and repair the issue.
Remember safety first! Never work on your vehicle while it's running. Disconnecting the battery's negative terminal is a good safety precaution before working on the electrical system.
