Low beam headlights not working: How to fix

Troubleshooting Low Beam Headlight Issues: A Complete Guide

When they malfunction, it can be both a safety hazard and an inconvenience. If your low-beam headlights aren’t working, this article will help you examine and fix the common issues that cause the problem.

Start your inspection by checking for melted plastic, a broken wire or corrosion in the headlight socket

Disconnect the electrical connector from the low-beam headlight bulb and examine its condition. Look for melted plastic, corroded pins, or any sign of overheating.

Melted low-beam headlight connectors

If you find any indication of overheating, STOP and skip down to the testing portion of this article.

Test for battery power and ground in the headlight connector

If your vehicle has only one headlight bulb on each side of the vehicle, the bulb contains two filaments, one for the high beams and one for the low beams. The electrical connector will have three terminals: a separate power wire for the low and high beam filaments and a shared ground wire.

With the headlight switch to the ON position for low beams, use a digital voltmeter to test for battery power. Connect the negative meter probe to the battery negative terminal or a good ground spot. Then, the positive meter probe was used to check for power in each of the terminals of the headlight connector. If you see a full battery voltage on the low beam terminal, power is getting to the low beam headlight. Leave the positive meter lead attached to that terminal and move the negative lead to the ground terminal in the connector. You should read the same voltage. If you don’t get full battery voltage, you have an open in the ground connection. If you get a voltage reading but it’s not the same as when the negative meter lead was connected to the battery, then you have high resistance in the ground circuit. Follow the ground wire to its termination point clean the ground connection, and retest.

If power isn’t getting to the low beam headlight

• Check the fuse(s)— Some vehicles have a separate fuse for the left and right low-beam headlights. Refer to the fuse box diagrams in your owner’s manual and check the fuses.

• Check for relays— If the fuses are good, check if your vehicle uses low-beam headlight relays. If so, swap the headlight relay with another relay in the fuse box with the same number. If that still doesn’t work, you’ll have to get a wiring diagram for your vehicle and find out which device switches power to the low-beam headlight relay.

In older vehicles, it’s usually the headlight switch. But in newer vehicles, it can be the generic electronic module (Ford), Body control module, Intelligent power module, front control module, etc.

If the low beam headlight connector is melted

Replace with a ceramic pigtail

©, 2016 Rick Muscoplat