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Troubleshooting Brake Light Failure

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Are your break lights working?

Are your break lights working?

So, Your Break Lights Are Out

While my car computer tells me a lot of things about the condition of my car, it ironically did not indicate that my brake lights were out. Both of them! Kind of strange, but it was not until another driver told me this. Luckily, no police patrols had seen this as I know I would have been stopped.

The brake lights are supposed to come on whenever you press on the brake pedal to slow or stop. There is nothing to indicate that the brake lights are indeed working (unlike when you turn on your headlights). These same brake light bulbs also function as turn signals. Most brake lights also are used for emergency lights; when the emergency light button is pressed, both brake lights will flash. The same brake light bulbs are also used for turn signals. The backup lights use a different bulb and are on when the car is moving in reverse. It is entirely possible that all of the above is working fine, but the brake lights still won't turn on (as in my case).

Troubleshooting No Brake Lights

If you find out that your brake lights are out, you can do a few things to diagnose.

  • Replace the bulbs for your car model.
  • Locate and check the car brake light fuse by pulling it out and making sure the internal filament is still connected.

After doing the above, do the brake lights come on when the brake pedal is pressed? If they don't, but the turn signals and emergency lights work fine, then the fix is something more serious, but if it's the brake light switch you may be able to fix it yourself.

Brake light switch

Brake light switch

The most common problem, if you have gotten this far, is the brake pedal switch, or brake light switch, that most cars have under the dash. The switch will activate the circuit when the brake pedal is pressed, making the car's rear brake lights will glow. When the pedal is not pressed, the circuit is cut to the rear lights and they are not lit. This can easily be seen by a non-mechanic. In some cars, like mine, the switch also controls the gear shifter mechanism for protection.

The switch may appear to be working normally when in reality the internal switch is stuck inside in the OFF position. Unless an engine code is pulled, it is hard to know. In my case, the code was 68-11. This indicates the switch has failed to work and needs to be replaced.

Depending on your car, this switch may or not be easily replaced without specific knowledge. Once the switch IS replaced, the brake lights should work (as long as the bulbs are new or good). If the brake lights are still not working, then your problem is an electrical issue, with broken or corroded wires or connections that need replacement.

In my case, the cost to replace the switch (including diagnostics) was:

  • $135 in labor
  • $11 for switch part
  • $6 for new bulbs

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.