• Brake
• Brake lights
• Cause
• Issue
• How to fix
• Car
• Vehicle
• Mechanic

Nothing is more important than the driver's safety, especially when driving at night; and one of the things that can guarantee your safety on the road is making sure that your brake and tail lights are doing their job.

Driving in bad weather or in the dark, without any of these lights could be dangerous and might cause accidents. 

However, it may take a while to notice when the brake lights or tail lights are not working since you have limited access to the backside while driving. Most often, the driver won't be aware until someone else notices and points it out. 

When this happens, the main cause of the issue cannot be determined right away, but there’s always a way to diagnose and fix it.

Here’s a more elaborate list of why your brake lights do not work but tail lights do, and how to fix them: 

Brake Lights vs. Tail Lights 

Brake lights and tail lights are different. 

Brake lights are a more luminous red in color on most cars; while the tail lights are just the normal, duller red. 

Brake lights turn on immediately when drivers apply pressure to the brakes to notify the motorists behind that they need to slow down accordingly; while the tail lights are engaged when the headlights are turned on and when you hit on the parking brake. They don't light up as bright as the brake light since it's designed for heavy rain and night time. 

Causes and Fixes

Faulty Light Bulbs

Blown or faulty bulbs is the most common reason why brake lights are not working and the tail lights are. This is especially true with older cars. 

The brake light and tail light often share the same bulb, but inside it are two different circuits. It's possible that one circuit is working, and the other one is burnt.

Checking or replacing the bulbs shouldn't require professional help. What you can do is read references or manuals on how to change a bulb. 

Open your car trunk and remove the tail lights back cover. Push the bulbs and turn them counterclockwise to remove from the socket and check if it has blown out.

If you see the bulbs darkened or the filaments are blown, then it's time to replace them. Make sure that the replacement bulbs are of the same type and wattage. 

Bad Brake Light or Turn Signal Switch

In some vehicles, the brake lights are powered through the same circuit as the turn signal light. So if your turn signal light is not working, then there's a big possibility that the brake lights aren't working either. 

The brake light switch is crucial in making your brake lights work. Your brake lights won't work if the switch is broken or damaged. 

You can use a multimeter to test the brake light switch. Check to see if you get a connection when the brake switch is released and no connection when you press or vice versa, depending on the brake switch type. 

If you're confident enough, you can also check the wiring diagram. Find the single wire which connects the brake light and turn signal switches. Access the electrical connector on the turn signal switch, press the brake pedal to activate the brake light switch then back probe the wire with a test light. If the test light doesn't illuminate, then you have to replace the wire. 

If you know how to replace the wire connecting these two, go ahead and do so. If not, you may need to seek assistance from your trusted mechanic. 

Broken Fuse or Fuse Box

Another way to check why the brakes are not working is by inspecting the power distribution center (PDC), or what we call, the fuse box. Any issues with the fuse box will affect the brake lights. 

Most cars have two or more fuse box and they are often located below the dashboard and under the hood. The fuse box supplies electricity to all electronic equipment in a car through wires.  

It's usually easy to notice the blown fuse just by looking at the plastic box. But if you want to be sure, you can use a digital multimeter. It can confirm if you can still use the fuse or not. 

Once you have identified the blown fuse, replace it with a new one. Make sure that the amperage is the same as the old one.  

Bad Sockets and Connectors

It's also best to check the pins and plugs of the brake light and tail light connectors. There may also be rust or corrosion in the sockets where the light bulbs are installed.

Make sure to clean them or use an electronic spray and install them again. 

Broken Wire

If all the parts mentioned above are functioning well, then there's one more thing to check to find out why the brake light is not working -  the wiring. 

Car wiring usually extends from the front to the rear of the car. The wiring to the brake light switch from the fuse panel and the switch to the bulb sockets and lights may be loose, broken or corroded. 

Be sure to replace the mentioned parts right away if you find any issues or damage.  

Electrical Ground

This is one of the things you should also check if either the brake lights or tail lights are not working. 

There could be several causes for bad electrical ground but the two main reasons are:

• Loose connection with the wire 
• Damage or corrosion of the wire ends

To fix this, connect the light switch to a good ground with a jumper wire or cable. Then, press the brake pedal. You have fixed your ground connection issue if the brake lights come on. If not, then you need to take your car or reach out to your mechanic.

Final Word 

There can be a number of reasons why your brake lights fail while your tail lights are functioning. If ever you encounter this, you may use this as a guide to aid you in identifying the source of the problem. It's still advisable to refer to your vehicle's manual or have your car checked by your trusted mechanic. 

Remember, it's your responsibility as a car owner and a driver to ensure that your brake lights and tail lights are working to avoid accidents and for safe driving.