1. Check the obvious:
* High beam switch: Make absolutely sure the high beam switch on your steering column is actually engaged. Sometimes it can feel like it's clicked, but isn't fully activated.
* Wiring and Bulbs: Inspect the high beam headlight bulbs themselves. They may have burnt out. Also, check the wiring connections at the bulbs for corrosion, damage, or loose connections.
2. Fuse Check (Multiple Possibilities):
While there's no single "high beam" fuse, there are several fuses that could affect the high beam circuit. You'll need to consult your owner's manual to locate the fuse box diagrams. Look for fuses related to:
* Headlight Circuit: This fuse often protects both high and low beams. A blown fuse in this circuit would affect both.
* Headlight Relay: The high beams might use a separate relay (an electrical switch). The fuse protecting the relay would need checking. Again, consult your owner's manual for relay locations.
3. Multi-meter Check (If comfortable):
If you're comfortable using a multi-meter, you can test for power at various points in the high beam circuit. This involves checking voltage at the switch, relay, and bulbs themselves. Caution: Always disconnect the battery's negative terminal before performing electrical tests to prevent accidental short circuits.
4. Relay Testing (More Advanced):
High beam relays can fail. If you find a potential power issue with your multi-meter, you might have to replace the relay.
5. Multi-Function Switch (Steering Column Switch):
The switch that controls your high beams is often integrated into the turn signal and wiper stalk. This switch can wear out or become internally damaged, preventing the high beams from activating even if the low beams work. This is a more involved repair, potentially needing replacement.
6. Wiring Harness Issues: This is a less likely possibility, but damage or breaks within the wiring harness running to the headlights could affect only the high beam circuit. This is difficult to diagnose without specialized tools.
In short: Start with the easiest checks (bulbs, switch, fuses). If the problem persists, consult your owner's manual for fuse and relay locations and diagrams. If you're not comfortable with electrical work, take your Expedition to a qualified mechanic. They'll have the tools and expertise to diagnose the problem accurately.
