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Ford Mustang V6 and Mustang GT 1994-2014: Why Don't My Headlights Work?

Every car needs headlights, especially a Ford Mustang GT. If you can get from here to there in a flash, you better be able to see what you're doing. Read on to learn what to do about those pesky headlight issues.

By Ben Mannino - September 23, 2015

This article applies to the Ford Mustang V6 and Ford Mustang GT (1994-2014).

If the headlights in your Ford Mustang aren't working, the good news is that the steps to getting to the root cause of the problem are fairly straightforward. Save yourself an expensive trip to the repair shop by following this simple troubleshooting guide.

Materials Needed

  • Multimeter
  • Screwdriver
  • Socket wrench
  • Plastic gloves
  • Bulb or ballast replacement
  • Silicon

Step 1 – Does either headlight work?

If you have one working headlight, then you can use it to test the other. The most common problem with a faulty headlight is the bulb, and you can easily swap one out for the other to test it out. If the light turns on, you found the problem.

  • Some headlights have a single bulb with two filaments for low and high beams, while others have one bulb for each. Be sure to test both and swap bulbs as necessary.
  • For HID headlights, the ballast can also go bad, so be sure to swap that as well if switching the bulb doesn't do it. Bulb or ballast, this is the place to start your troubleshooting steps.

Pro Tip

Avoid touching any part of the glass of an HID bulb, as this can shorten its lifespan significantly.

Step 2 – Are both headlights off?

In this case, you most likely have no voltage getting to the headlights due to a wiring problem, bad fuse, relay, or switch.

  • The first step is to locate the headlight fuse and check to see if it has blown. If so, replace it and try again. If it burns out again, you must have a short somewhere in the headlight circuit that will need to be identified.
  • If the fuse is OK but you still have no lights, check for 12 volts on the power side of the fuse. If you don't have power, there has to be a wiring problem between the fuse block and the battery. Check your Mustang's circuit diagram and check connectivity along the harness.
  • If the fuse is good and you do have power, then you will need to check the headlight relay. Chances are you have a bad one, and replacing it should solve the problem.
  • If you have tried all of this and still can't get power, you may have a defective headlight switch. As simple a part as this might be, it could be challenging to replace and might warrant a trip to the dealer.
Figure 1. Locate the blown fuse, relay, or switch.

Step 3 – Are the headlights working but not very bright?

In this case, there could be moisture on the inside lens cover, dirt or discoloration on the outside cover, or the lights are not aimed properly.

  • Moisture can be a pain to get out, but sometime it can be done be drilling small vent holes to allow the moisture to escape. Of course you will need the vehicle to be in a dry spot, preferably in direct sunlight, to allow the water to evaporate. Then, seal the holes with silicon and it should be a big improvement.
  • Dirt or discoloration can vary from one headlight to another, but there are plenty of cleaning compounds that can do a good job in removing most of the dirt.
  • The aim of your headlights can be adjusted by turning the adjustment screws on the back or top of the headlight. It helps to have the car facing a garage door or wall to find that optimum position.

A little detective work can go a long way to getting your headlights working in top condition.

Featured Video: How to Replace Ford Mustang Headlights

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