* Blown Fuse(s): This is the *first* thing to check. Your owner's manual will show you the fuse box location and diagram. Look for fuses related to tail lights, instrument panel lighting, and potentially the body control module (BCM) if it's fuse-protected. Replace any blown fuses *with the correct amperage fuse*. Using a higher amperage fuse is dangerous and can cause a fire.
* Faulty Body Control Module (BCM): The BCM is a computer that controls many electrical functions, including lights and the instrument cluster. A malfunctioning BCM can cause a complete loss of these functions. Diagnosing this requires a scan tool or specialized electrical testing equipment.
* Wiring Issues: A break or short in the wiring harness could interrupt the power to the taillights and dash lights. This is harder to diagnose and may require tracing the wiring circuits. Look for damaged wiring near the taillights, under the dashboard, and in areas where the wiring harness might be rubbing against metal. Corrosion in connectors is another possibility.
* Bad Ground Connection: A poor ground connection can cause erratic electrical behavior. Check for clean, tight ground connections near the taillights and the instrument panel.
* Ignition Switch Problem: While less likely to affect *both* taillights and dash lights simultaneously, a faulty ignition switch could interrupt the power supply to certain circuits.
* Alternator/Battery Issues (less likely): A completely dead battery or a failing alternator could cause a power loss, but usually you'd see other symptoms like the engine struggling to start or other electronics failing.
Troubleshooting Steps:
1. Check the fuses: This is the easiest and cheapest step. Replace any blown fuses.
2. Check the ground connections: Make sure all ground connections are clean and tight.
3. Inspect the wiring: Look for any visible damage to the wiring harness, particularly near the taillights and the dashboard.
4. Test the bulbs: While less likely if *all* taillights are out, ensure your taillight bulbs are still functional.
If checking fuses and looking for obvious wiring problems doesn't solve the issue, you'll likely need to take the car to a qualified mechanic or auto electrician for proper diagnosis. They have the tools and expertise to test the BCM and other electrical components. Mentioning "no taillights and no dash lights" will help them focus their diagnosis.
