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Brake Lamp Bulb Fault (Causes & Fixes)

Updated: 14 hours ago

✔ This article has been fact checked.


A brake lamp bulb fault can occasionally occur on your vehicle, if this happens your brake lights will not turn on in response in you pressing on the brake pedal. This issue can be very dangerous if left unfixed.


There are many causes of a brake lamp bulb fault. Blown bulbs, faulty brake light switch, damaged or loose wiring, blown fuses, and malfunctioning relays and modules can all cause this fault.



It's most commonly a blown bulb or fuse that causes this issue, but it can be any number of things.


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brake lamp bulb fault warning message on car dashboard

What Does It Mean?

Some vehicles have a built in system for detecting blown bulbs and issues with exterior lights, this can cause a warning light or "brake lamp bulb fault" message to appear on your dashboard.


In general, this warning refers to the brake pedal not illuminating the brake lights. Not all vehicles will see this warning message, and it does not always occur.


This alert that appears on some cars is only a warning and you should visually check all exterior lights to see if they're working properly.



Causes of a Brake Lamp Bulb Fault

There are a multitude of possible causes for a brake light fault, including the following.


  1. Blown bulbs

  2. Faulty brake light switch

  3. Damaged or loose wiring

  4. Blown fuses

  5. Malfunctioning relays and modules


Blown Bulbs

Brake light bulbs, as well as most other bulbs, don't last the life of the vehicle. They will ultimately stop illuminating since they deteriorate with age, lose their brightness, and eventually stop working completely.


The brake lamp bulb may flicker or not illuminate at all due to a blown bulb.



Some brake light bulbs last a lot longer than others, halogen bulbs typically last the shortest amount of time and LED bulbs will last the longest.


Note that some cars may throw a CANbus error if you replace a halogen bulb with an LED equivalent.

a car with its brake lights illuminated

Faulty Brake Light Switch

Only when the driver hits the brake pedal do the brake lights illuminate. When you press the brake pedal, a brake switch activates the brake light lights.


This switch is located by the pedals. Sometimes it may be electronically controlled by a brake pedal position sensor, in which case this would be the issue.


A faulty brake light switch is another common cause of a brake lamp fault.



Damaged or Loose Wiring

Sometimes the issue may damaged or loose wiring, it could be caused by an animal chewing through wires, corrosion, vibration causing a wire to be damaged or it could be a connector that has come loose.


You could check all the brake lights for any wiring issues, or it could be the wiring related to the brake light switch, fuses and relays, etc.


Any damage to the wining or connection that has come loose can result in a brake lamp bulb fault, it may also cause flickering of a bulb.


damaged car wiring

Blown Fuses

Fuses protect components from electrical surge and prevent too much power going to them.


The majority of fuses have two terminals, and these terminals are connected by a thin piece of metal. It will not send electricity to the primary component it is protecting if the metal strip breaks or the fuse burns.


When a fuse to a brake light bulb, brake pedal position sensor, or brake switch, blows you will likely encounter a brake lamp fault.