1. Faulty Headlight Switch: While you mentioned the switch is new, it's still worth checking. Ensure the switch is properly installed and making proper contact. Try testing the switch with a multimeter to ensure it's functioning correctly.
2. Wiring Issues: Inspect the wiring harness for any loose connections, breaks, or damage. Pay special attention to the connectors behind the headlight assemblies and the fuse box. Ensure all connections are secure and free of corrosion.
3. Headlight Relay: Most Ford trucks have a headlight relay that controls the power supply to the headlights. A faulty or damaged relay can prevent the headlights from working. Locate the headlight relay (usually in the fuse box) and check for any signs of damage or corrosion. If needed, replace the relay with a new one.
4. Fuse Box: Double-check all the fuses related to the headlights in the fuse box. Sometimes a fuse can blow even if it looks visually intact. Use a multimeter to test each fuse for continuity. Replace any blown fuses.
5. Headlight Ground: Ensure the headlights have proper grounding. Check the grounding connections on the headlight assemblies and make sure they're clean and making good contact with the chassis or designated grounding points.
6. Multi-Function Switch: In some Ford models, the headlight switch is part of a larger multi-function switch that also controls other features like turn signals and windshield wipers. If this switch is faulty or has loose connections, it may affect the headlights' functionality.
If none of the above steps resolve the issue, it's recommended to have a qualified mechanic or an auto electrician diagnose the problem, especially if it involves complex electrical systems or specific components like the solenoid fuse box.
