HomeTips & GuidesHow to Wire a Brake Light Switch?

How to Wire a Brake Light Switch?

How to wire a brake light switch? 

Do you check your brake light regularly? Any dysfunction in the brake lights can be dangerous for you and the people driving around you.

Before you run directly to a professional, you may want to investigate the problem yourself. 

Sometimes, it may be an easier fix than you think, especially when there is something wrong with your brake light switch.

Table of Contents

Brake light switch wiring understanding:

Brake light switch is common in modern trucks, including Ford, Chevrolet, and others. As a part of the brake pedal assembly, it is under the dash. Sometimes, you can also find it near the pedal lever top.

The wiring of this switch is not very complex, and you can easily replace it. In this wiring system, one end has bulbs in sockets connected to the harness, while the other has a brake switch.

Pressing the pedal creates a contact, completing the circuit and lighting up the brake lights. This brake light switch system draws power from the car’s battery.

Earlier, hydraulic pressure was used to drive the brake system, but it was more prone to failure. So, manufacturers opted for the brake light switch mechanism over time as it was more reliable.

In this modern mechanism, a low-volt control circuit operates the main power source switch with the help of a relay. As a result, the whole system becomes highly reliable and long-lasting.

This whole circuit comprises a network of wires, which runs from the battery to the fuse block, from there to the switch and from the switch to the brake lights.

Some of these wires also go to the body controller. You can find all these wires bundled in a harness, running through the entire vehicle.

Checking the brake light wiring harness 

Checking the brake light wiring harness 

Repair or replace a faulty brake light switch:

Here, we mainly discuss analog brake light switches and not the digital sensors in modern cars. 

Indicators of brake light switch failure:

  • The brake lights do not work even when you press the brake pedal
  • Brake lights are ON irrespective of whether you press the pedal or not
  • Brake lights are working intermittently

Troubleshooting brake light switches that don’t go off:

Try operating the pedal with your hand and check how the pedal movement affects the light switch operation.

  • Disconnect the connector to adjust the switch. 
  • Now, rotate the brake light switch, moving the sensor contact away and near the brake pedal. Place the sensor contact in such a position that you need not press the brake pedal too much to turn ON the lights. The lights should turn on even when you slightly press the pedal.
  • Also, check if you can adjust the switch position. For this, shift the brake light switch in the front or back, changing it according to the pedal position.
  • If you cannot find any of the above issues, there can be a problem with the internal switch mechanism. In this case, you must call a professional or refer to the manual to replace the switch.
The brake light switch under the pedal car

The brake light switch under the pedal car

Replace the brake light switch:

If you find a problem with the switch, you must replace the switch at fault with these steps:

Prepare for the safety measures:

No matter how small a component is, you must follow the safety procedure. So, disconnect the switch from the power source if it is connected to the electricity. With this, you protect your car’s components from blowing out due to any potential short circuit.

Look for the switch position:

The style and location of the brake light switch may vary according to the vehicle. Some switches are on the pedal lever, while others are near the bracket. Also, some switches are present beneath the dash. Mark the position of the brake switch so that you do not need to adjust the new switch too much.

Choose the switch:

Brake switches are of different types, including hydraulic ones. You must get a switch that is suitable for your vehicle. Before you buy a switch, note down your car’s model, make, and year so that you can tell the seller and get the right switch for you.

Remove the old brake switch:

  • Disconnect the harness and place it safely.
  • Unclip and unbolt the switch and remove it.

Install the new switch:

While installing the new brake light switch, follow the reverse order of removing the old switch, i.e., first mount the switch, secure it properly, and then connect the pigtail to the switch connectors.

Lastly, adjust the switch position precisely and connect the battery cables to start the power supply. 

Test the new brake light switch:

Press the brake pedal and see if the brake lights are turning ON and OFF accordingly. The brake lights should go ON and OFF with a slight movement of the brake pedal, mostly between ¼ and ½ inches. However, the specs may vary according to the vehicle. So, check your service manual for it.

Now, it’s time to test drive your vehicle. Ensure that the shift lever moves only when you press the brake pedal.

If the brake light switch wiring has a problem

Sometimes, the switch has no problem, but you must connect the brake light switch to the circuit for repair. The process will start at the fuse block.

Look for the fuse block’s hot side and connect a power wire either from the second pin of the fuse block or from the terminal of the brake light fuse. This wire connects to the brake light switch.

Now, the switch is connected to a plug wiring harness, so you must splice the power wire to the plug’s power wire. You can refer to your vehicle’s wiring diagram for the exact wire. With this, the switch will start getting power. 

Connect the switch’s output wire to the brake light wiring harness.

If you remain careful, you may need not replace the whole wiring circuit. Just look for the damaged wires or any damaged components and replace them.


If you follow all these steps carefully, things are way easier than you think when fixing the brake light switch.

However, diagnosing the problem before you start repairing anything is equally essential. There is no point in adjusting the brake light switch or sensor if the real problem lies in its wiring or the connector. 

If you need to replace the brake light wiring harness, Cloom is here to help you. We deal in all automotive wiring harnesses and provide custom designs to fit seamlessly in all modern trucks and vehicles.

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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