- 1). Check your headlight operation. Crank the engine, turn on the headlights and stand in front of your Ranger to determine which headlights are nonfunctional. If your headlights work but flicker, you likely have a faulty headlight switch or a wiring problem. This will require professional repair. If only one of your headlights is nonfunctional, you probably have a faulty bulb or relay. Turn on your high-beam ("bright lights") headlights to check their operation. If they work but your low-beams do not (or vice versa), you probably have a faulty bulb or relay.
- 2). Inspect the bulbs. Remove the bulb sockets from the rear of your headlight assembly and inspect their filament. If the bulb is bad, the filament will be broken; if it's good, the filament will be connected. Check your high-beam and low-beam bulbs. Replace the bulbs if necessary. If you do not know how to identify a faulty bulb, see Resource for examples of "good" and "bad" bulbs.
- 3). Check your headlight relays for continuity using a multimeter. The process of checking the relay will depend on the type of relay and the number of coils and switches in the relay. If you do not know how to use a multimeter, let a professional handle this--or consider replacing the relays once you've eliminated other possible problems (relays are relatively inexpensive). Replace the relays if they are bad or if you've eliminated all other possible problems. Most Ford Rangers contain two headlight relays: one for the high-beam and one for the low-beam. Use your engine-bay fuse box as a guide; relay type and location will depend on the year model and engine size.
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