What a brake light switch does and why it fails
Your brake light switch is a small electrical component mounted under the dashboard near the brake pedal. When you press the brake pedal, the switch closes an electrical circuit that tells your brake lights to turn on. When you release the pedal, the switch opens and the lights turn off.
A brake light switch fails when the internal contacts wear out or corrode, or when the plunger that the pedal pushes against gets stuck. When this happens, your brake lights may stay on all the time, stay off all the time, or flicker unpredictably. Some vehicles also use the brake light switch signal to set up the brake warning light on your dashboard or to unlock the steering wheel when you press the brake.
Replacement is straightforward on most vehicles and takes 15 to 45 minutes depending on how accessible the switch is under your dash. You do not need special tools beyond a basic wrench or socket set and a screwdriver.
Key Takeaways
- The brake light switch sits under the dashboard near the brake pedal and closes an electrical circuit when you press the brake.
- A faulty switch causes brake lights to stay on, stay off, or flicker, and may trigger a warning light on your dashboard.
- Replacement involves disconnecting the electrical connector, unbolting the old switch, and installing a new one in the same position.
- A replacement switch costs between $15 and $75 depending on your vehicle, and the job takes less than an hour on most cars.
- If your brake lights do not turn on after replacement, check that the electrical connector is fully seated and that the new switch is positioned correctly against the brake pedal.
Locate the brake light switch under your dashboard
The brake light switch is mounted on a bracket directly above or to the side of the brake pedal arm, under the steering column. You will need to lie on your back or crouch under the steering wheel to see it. Use a flashlight to locate the switch — it is a cylindrical component about the size of a AA battery, with an electrical connector on one end and a mounting bracket on the other.
The switch has a plunger that extends toward the brake pedal. When the pedal is at rest, the plunger is pushed in by the pedal arm, keeping the switch in the open position. When you release the brake, a spring pushes the pedal back up and the plunger extends, closing the switch.
If you cannot locate the switch, check your vehicle's service manual or search online for "[your year, make, model] brake light switch location." Some vehicles mount the switch in slightly different positions, and a few older models use a switch mounted on the master cylinder instead of under the dash.
Disconnect the electrical connector and remove the old switch
Once you have located the switch, unplug the electrical connector by pressing the release tab or clip on the connector and pulling it straight away from the switch. The connector should come free without force. If it is stuck, wiggle it gently side to side while pulling.
Next, unbolt the switch from its mounting bracket. Most switches are held in place by one or two bolts or a single clip. Use a wrench or socket to remove the bolts, or squeeze the clip to release the switch. The switch should slide out of the bracket once the fasteners are removed.
Before you install the new switch, inspect the mounting bracket for cracks or corrosion. If the bracket is damaged, it may not hold the new switch securely. A damaged bracket should be replaced at the same time as the switch.
Install the new brake light switch
Position the new switch in the mounting bracket so that the plunger faces the brake pedal arm. The switch should sit at the same angle and distance from the pedal as the old one did. Slide the switch into the bracket and find it with the bolts or clip you removed earlier. Tighten the bolts firmly but do not overtighten — you only need enough pressure to hold the switch in place.
Reconnect the electrical connector by pushing it straight onto the switch until you hear or feel a click. The connector should be fully seated and should not come loose if you tug on it gently.
Before you test the switch, press the brake pedal several times to make sure the plunger moves freely and that the pedal does not feel different than before. The plunger should extend and retract smoothly without binding or sticking.
Test the brake lights and dashboard warning light
Start the engine and have someone stand behind the vehicle while you press the brake pedal. The brake lights should turn on when ready and stay on as long as you hold the pedal down. When you release the pedal, the lights should turn off when ready.
If the lights do not turn on, check that the electrical connector is fully seated on the switch. If the connector is seated but the lights still do not work, the new switch may be defective or you may have installed it backward. Disconnect the connector, remove the switch, and reinstall it, making sure the plunger faces the brake pedal.
Also check your dashboard for a brake warning light or ABS light. These lights should turn off once the engine is running and the brake lights are working. If a warning light stays on, the vehicle's computer may not be recognizing the new switch signal. This usually means the switch is not positioned correctly or the connector is not fully seated.
Choosing the right replacement switch for your vehicle
Brake light switches are not universal — the connector type, plunger length, and mounting bracket vary by manufacturer and model year. Before you buy a replacement, confirm the part number from your vehicle's service manual or from an online parts catalog using your vehicle identification number (VIN).
Replacement switches are available from auto parts stores, online retailers, and dealerships. Aftermarket switches from brands like Standard Motor Products or Motorcraft typically cost $15 to $40. OEM switches from your vehicle's manufacturer cost $30 to $75. Both types are reliable, though OEM switches come with a longer warranty.
Some vehicles have multiple brake light switches — one for the main brake lights and a separate one for the brake warning light or transmission lock. Check your manual to confirm whether you need to replace one switch or more than one.
When to seek professional help
If you are not comfortable working under the dashboard or if your vehicle has limited space under the steering column, a mechanic can replace the switch in 30 minutes to an hour. Labor costs typically range from $50 to $150 depending on your location and the shop's hourly rate.
You should also have a professional diagnose the problem if your brake lights are not working but you are not sure whether the switch is the cause. A faulty switch is the most common reason brake lights fail, but a blown fuse, a wiring problem, or a bad bulb can also cause the same symptoms. A mechanic can test the switch with a multimeter to confirm it is defective before replacing it.
If the new switch does not fix the problem, or if your brake lights flicker or behave erratically after replacement, have the wiring and connector inspected for corrosion or damage. Corroded wires or connectors can prevent the switch from working properly even if the switch itself is new.
Frequently Asked Questions
How do I know if my brake light switch is bad?
The most common sign is brake lights that stay on all the time, even when the engine is off and the brake pedal is not pressed. Other signs include brake lights that do not turn on at all, lights that flicker when you press the brake, or a brake warning light on your dashboard that stays on. You can test the switch by pressing the brake pedal and listening for a clicking sound under the dash — a working switch makes a distinct click when it closes.
Can I drive with a broken brake light switch?
If your brake lights are not working, you should not drive the vehicle on public roads. Brake lights are a safety feature that warn drivers behind you that you are slowing down. Driving without working brake lights is illegal in most places and puts you and other drivers at risk. If the switch is stuck in the on position and your lights stay on, you can drive carefully to a repair shop, but have the switch replaced as soon as possible.
Will replacing the brake light switch affect my transmission or steering?
On some vehicles, the brake light switch also sends a signal to the transmission to prevent shifting out of Park without pressing the brake, or to the steering column to unlock the wheel. If your new switch is not positioned correctly or the connector is not fully seated, these functions may not work. Test the transmission shift lock and steering wheel lock after replacement to make sure they work normally.
What if the new switch does not fit in the mounting bracket?
This usually means you ordered the wrong part number for your vehicle. Double-check the part number against your VIN and your vehicle's service manual. If the part number is correct but the switch does not fit, the mounting bracket may be bent or damaged. Inspect the bracket for cracks or dents and replace it if necessary.
Do I need to bleed the brakes after replacing the brake light switch?
No. The brake light switch is an electrical component that does not interact with the hydraulic brake system. Replacing it does not require bleeding the brakes or any other brake system maintenance. If you are bleeding the brakes for another reason, you can replace the brake light switch at the same time.