Here is another of our maintenance publications, this time about the reasons for the brake light not working but bulb is good. This is a safety concern that needs to be fixed before you get the car safely on the road again.
In a situation like this, even if you replace the bulb, the brake light will not work, but the tail light will work. You would think you have a bad bulb and have to buy another pack. The chance is that you will get the same result of the brake light not turning on.
You will notice this problem when you press the brake. The brake light will stay off but turning the tail lights on will light in the same bulb light.
Brake light not working but bulb is good: causes and fixes
This section of the publication compiles possible causes and fixes recommended by experts or mechanics. Some of the problems may be fixable by you but others require an experienced mechanic.
Below are the reasons and fixes for your brake light not coming on though the tail light works:
Failing light bulbs
We know that your bulbs are not the cause but for some people, the bulb could be faulty. So, let’s begin by addressing the bulb as the possible reason for the brake light not working.
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The tail lights of a car engage when you turn on the headlights or the parking brake is on. Brake lights immediately light up when you match the brakes.
The tail lights are mostly red but the brake lights are a more luminous red in most vehicles.
If the light bulb is blown out, it could be the reason. In an older vehicle, for instance, depressing the brakes without the brake lights lighting up immediately could even be a mechanical fault damaging the bulb.
How to fix
Perhaps, an inspection or repairs would fix the problem. This is left for the mechanic to determine since there could be faulty components causing new bulbs to get blown.
You could always try using the bulb on a different vehicle after it refuses to light in your car to know if it is indeed blown.
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If inspection shows the bulb is blown and a fix is made, remove the back cover of the taillights back cover and replace it.
Damaged fuse box and light switch
Wires responsible for supplying electricity to the electronic equipment of the vehicle run through a fuse box. In a modern vehicle, you would have two fuse boxes to inspect.
If the fuse is broken, your brake light will stop working, even though the bulb is good.
You would need to locate the brake light fuse. Refer to the automaker’s manual to know the correct steps.
How to fix
The solution to the damaged fuse box is to get a new one for replacement. Ensure to verify the amperage of the new unit to be sure it is the same as the previous one to permanently fix the problem.
Faulty electrical ground
A ground point in a vehicle acts as the conductor between negative and positive terminals. How your car uses electrical circuits is similar to those in your home. The closed-circuit system of a car is energized by the battery.
If the electrical ground is faulty, your brake light will no longer work even though the bulb is in good condition. Typically, the taillights still work, only the brake lights do not. You will also notice that the brake light switch is still operational.
How to fix
To fix a brake light that won’t work, though the bulb is good, inspect for bad electrical ground. Typically, this results from corroded or broken wires.
If the brake light turns on after you connect the light switch to a good ground and press the brake pedal, the ground connection needs to be repaired.
Loose or corroded wiring
If your light bulb, fuse box, and electric ground are functional, corroded wiring could be the reason for the brake light not working but the bulb is good.
You want to inspect the wiring to the brake light switch from the fuse panel. Also, inspect the wiring to the bulb sockets from the switch. If broken or corroded, the wiring is the reason for the brake light problem.
How to fix
You can fix this issue by ensuring that the loose connections or corroded bulb housing is fixed. An experienced mechanic is in a position to find and fix these problems.
Failing turn signal switch
The turn signal switch is a lever mechanism usually affixed to the inner part of the steering column. It controls the blinkers. It is also commonly known as a blinker switch or turn signal arm.
In some vehicles, the same circuit powering the turn signal light also powers brake lights. As such, if the turn signal light is faulty in your car, this can cause the brake lights not turning on.
How to fix
The solution here is to get a replacement turn signal switch or the wire connecting the turn signal and brake lights. You may need the services of a trusted mechanic to fix this issue.
We have addressed the major issues stopping your brake light from turning on. Note that the possible causes highlighted above pay attention to the fact that the bulb is still working and the tail light functions properly.
While trying to fix the problem yourself, have your automaker’s manual handy for reference. You could always refer to your automaker’s online resources to fix issues.
A trusted mechanic is always the go-to solution nonetheless. A mobile mechanic can even trace your location to have the tail light fixed to ensure safe driving and minimize the likelihood of road accidents.