1. Check the Bulbs:
* Access: Open the hood and locate the high beam headlight bulbs. They're usually the inner bulbs on each headlight assembly. Consult your owner's manual for precise location and bulb type (H4 or 9004 are common possibilities).
* Inspection: Carefully remove the bulbs and inspect them closely. Look for a broken filament (the thin wire inside). If you see a break, replace the bulb with a new one of the correct type. Always handle bulbs by the base to avoid touching the glass.
2. Check the Fuses:
* Location: Your owner's manual will show the fuse box location (usually under the hood or in the dash). Find the fuses related to the headlights (often labeled "Headlights" or with a headlight symbol).
* Inspection: Check each fuse visually for a blown filament (a broken wire inside). If found, replace it with a fuse of the same amperage rating.
3. Check the Headlight Switch:
* The switch itself is less likely to be the problem, but worth considering. The switch might be failing internally, causing intermittent or no high beam function. This is usually diagnosed by testing with a multimeter and is best left to a professional unless you have electrical experience. Replacing the switch is a moderately difficult job that will involve some dash disassembly.
4. Check the High Beam Relay (if applicable):
* Location: Some vehicles use relays for high beams, while others use the switch directly. Again, your owner's manual or a wiring diagram will be crucial in identifying if a relay exists and its location. The relay is usually a small square or rectangular component in a fuse box or under the hood.
* Testing: If you locate a high beam relay, you can try swapping it with another relay of the same type (if you have one that's not critical, for testing purposes only). If the high beams work after the swap, you've likely found the faulty component.
5. Check the Wiring:
* This is the most difficult to diagnose without electrical testing experience. Problems in the wiring harness (broken wires, corrosion, loose connections) can cause intermittent or complete high beam failure. This requires careful visual inspection of the wires running from the headlight switch, through the relay (if present), to the headlights. A multimeter is necessary to check for continuity and proper voltage.
6. Multi-meter Diagnosis:
* Using a multimeter to test the voltage at various points in the circuit (at the switch, relay, and headlight connectors) is the most effective way to pinpoint the issue. However, this requires a basic understanding of electrical circuits and safety precautions with automotive electrical systems.
Important Considerations:
* Owner's Manual: This is your best resource for locating fuses, relays, and bulb types.
* Wiring Diagram: A wiring diagram (available online or at auto parts stores) can be invaluable for tracing the electrical path of the high beams.
* Safety: Always disconnect the negative battery terminal before working on the car's electrical system. Headlights are hot when in use; allow them to cool down before handling.
If you're not comfortable working with car electrical systems, it's best to take your LeSabre to a qualified mechanic for diagnosis and repair. Attempting repairs without the proper knowledge and tools can lead to further damage or injury.
