* Faulty Instrument Cluster Bulb(s): The most likely culprit is a burned-out bulb or bulbs within the instrument cluster itself. The fact that only half the lights are out suggests a problem isolated to that section of the cluster's lighting circuit. You'll need to access the instrument cluster (likely involves removing the bezel) to inspect and replace the affected bulbs.
* Loose or Damaged Wiring: A loose wire connection within the instrument cluster or its wiring harness could interrupt the power to specific bulbs. Check for any loose or broken wires, especially in the area supplying power to the tachometer's lighting.
* Faulty Instrument Cluster Circuit Board: Less likely, but possible, is damage to the printed circuit board (PCB) within the instrument cluster. This often manifests as intermittent issues or problems with multiple components. Repairing a damaged PCB usually requires specialized electronics expertise.
* Faulty Ground: A poor ground connection can affect the entire instrument cluster, or parts of it. Check for a clean ground connection to the instrument cluster.
Troubleshooting Steps:
1. Visual Inspection: Carefully examine the instrument cluster. Try gently tapping around the area where the lights are out (while the ignition is on). A loose bulb might make a rattling noise or show signs of movement.
2. Bulb Replacement (Most Likely): Access the instrument cluster and replace the suspected bulbs. Consult a Corvette repair manual or online resources for specific instructions on how to remove the cluster and access the bulbs. Note that bulb types and sizes vary, so you'll need the correct replacements.
3. Wiring Inspection: Carefully examine all wiring connections to and within the instrument cluster. Look for corrosion, broken wires, or loose connectors.
4. Ground Connection: Check the ground connection for the instrument cluster. It should be a clean, tight connection to a good ground point on the chassis.
5. Professional Help: If you're not comfortable working with car electronics, take it to a qualified mechanic or auto electrician. They have the experience and tools to diagnose and repair the problem efficiently.
Remember to disconnect the battery's negative terminal before working on any electrical components to avoid short circuits or injury.
