“One Tail Light, Low Beam, High Beam, or Daytime Running Light Works? Learn How to Check the Bulb and Fuse.”
If your car or truck has one headlight not working, such as one high beam or low beam not working, one tail light working, or the daytime running lights are not working on one side, there might be a problem with the bulb or the fuse. If one light just won’t work or you replaced the bulb and the light still doesn’t work, this article explains how to check the fuse and what else might be the cause.
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How to Check a High Beam, Low Beam, Tail Light, Daytime Running Light, or One Headlight Not Working
How to Test the Fuse
Steps for Testing a Headlight, High Beam, Low Beam, or Running Light Not Working
- Locate the Fuse
Find the fuse box for the faulty light. Remove the fuse box cover and find the fuse on the legend.
- Connect a Test Light
Connect the test light to the negative battery terminal. Touch the positive terminal with the test light to test it. If the test light is working, it should turn on.
- Test the Fuse with a Test Light
Check for power on both sides of the fuse with a test light. If the test light does not illuminate for one of the sides, remove the fuse.
- Inspect a Fuse with No Power
Remove the fuse with no power and inspect it. If the wire inside is split or broken, like in the picture below, the fuse is defective.
How to Test Headlight Bulb
- Remove the light not working from the vehicle
- Inspect the bulb for signs of wear like cracking or burning
- Find a bulb of the same type and insert it into the bulb socket
- Turn on the lights and see if the new bulb works
If One Headlight Is Not Working, Check the Headlight Switch
Sometimes a faulty headlight switch or multi-function combination switch is the cause of one headlight not working. If one of the modes like high beam or low beam is not working when selected, the problem may be the switch, especially if there is no problem with the bulb, fuse, or the electrical power to the switch.
Read more about the difference between high beams, low beams, and running lights.
This video shows the basic steps for replacing the multi-function combination switch.
Check the Wiring for the Headlight Not Working
Sometimes wiring can melt, tear, or break. Check the headlight socket’s wiring and electrical connector for damage. If the wiring has been chewed or is broken, or if the electrical connector has discoloration or no power, replace it.
Read more about how to replace an electrical wire.
Related Content
- How to Fix a Broken Wire
- How to Replace a Headlight Socket
- What Are Low Beam Headlights?
- Why Are My Headlights Dim?
- Is It Illegal to Drive with a Headlight Out?
- What Type of Headlights Do I Have?
- How to Test a Fuse with a Multimeter
- How to Tell if a Relay is Bad in a Car, Truck, or SUV
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Hey just wondering about what might be wrong i put new bulbs in about 3 months ago and today might right fog light won’t turn on and my right headlight doesn’t work on low beam but it works on high and park any thoughts on what this could be cheers
Either bulb or fuse more than likely.