Brake lights are an important part of a car's braking system. The brake light serves to warn other drivers that you are slowing down so that a faulty brake light can result in an accident. If the brake light stays on even if you don't step on the pedal, it's possible that the switch is faulty or the fuse is blown. Check each light to make sure the brake lights are working properly before returning to driving.
Step
Method 1 of 3: Checking for Damage to the Brake Light Switch
Step 1. Disconnect the battery
Before working on the electrical system in a vehicle, you should always disconnect the battery. Thus, you are safe from electric shock or other damage while working. Use a wrench to loosen the grounding wire with the negative terminal on the battery. Set the cable aside and tuck it against the side of the battery.
- You can find the negative terminal by looking for the word “NEG” or the minus symbol (-) on the battery.
- The positive terminal connection does not need to be disconnected.
Step 2. Wear eye protection
In this project, you will be required to look under the dashboard so you need to protect your eyes from falling debris. You don't need gloves, but feel free to wear them to prevent puncture of the wires.
- Goggle-type eye protection (aviation glasses) will provide maximum protection.
- Eye protection goggles are sufficient for this project.
Step 3. Locate the brake pedal switch
The brake pedal switch is a button located along the stem of the brake pedal, above the foot pads. When the pedal is pressed, the brake rod presses the button that turns on the brake light.
- If you do not find the brake pedal switch, consult the vehicle's user manual.
- The switch has a pigtail cord and will ride directly behind the brake pedal.
Step 4. Disconnect the pigtail wire from the switch
The pigtail wire for the switch will be held in place by the plastic case. Press the release clip on the plastic housing so that the pigtail is disconnected from the switch, then pull on the plastic part of the pigtail to release it.
- Do not pull on the cable yourself as you could break it from the pigtail restraints.
- Work very carefully so as not to break the plastic clip.
Step 5. Look and check the switch wires
Look inside the pigtail restraints for signs of burning or melting. If the cable overheats, the pigtail may be damaged and the brake light will continue to flash. Any signs of damage to the pigtail cable can cause brake light problems.
- Damaged pigtails must be replaced in order for the brake lights to function properly.
- You may need to order a light switch pigtail from an agent if it is not available at an auto repair shop or shop.
Step 6. Test the switch back motion
The switch itself is a long button that is pressed when the foot hits the brake pedal. While still under the dashboard, press the pedal or on the button itself and watch if the button rises back up when released. If not, it means that the "sticky" button is in the on position.
- If the button is attached to the ON position, the brake light will always be on.
- Have your friend stand in the back of the car and look at the lights when you press and release the switch.
- If the button doesn't affect the light, either a fuse has blown or the switch itself is faulty.
Method 2 of 3: Installing a New Brake Light Switch
Step 1. Make sure the cable restraint connection is disconnected
Before removing the brake light switch, make sure the pigtail is disconnected. If the connection was disconnected before checking for damage, leave it hanging while you release the switch. If not, disconnect now by pressing the plastic release and pulling on the plastic case.
- Unless they need to be replaced, the pigtail restraints will return with a new brake light switch.
- If the release is damaged, use cable tape to secure the pigtail during reassembly to avoid buying a new one.
Step 2. Remove the switch from the brake pedal latch
Different vehicles, different linkage (linkage) the light switch to the brake pedal. If it's not clear how to remove the switch from the pedal, consult the user manual for the year, make, and model of your vehicle.
- The switch should be held in place by 1-2 small screws.
- Be careful not to lose the rider hardware. This device will be reused when installing a new switch.
Step 3. Slide the new switch into place
If the old switch has been removed, install the new switch exactly where the old switch was. Use the previous rider hardware to close the new switch like the old one.
Replace the screw that secures the switch if it breaks when removed
Step 4. Reconnect the switch to the hook and restraint
Connect the brake light switch pigtail to the new switch and reattach all previously disconnected connections to remove the old switch. The switch should now be behind the brake pedal rod and connected to the vehicle.
- Reconnect the battery and start the vehicle.
- Have a friend stand in the back of the vehicle while you test the new brake light switch and make sure it works.
Method 3 of 3: Replacing Blown Fuses
Step 1. Locate the fuse box in the vehicle
Most vehicles have two fuse boxes in the body. Usually one of the boxes is located under the hood, and the second box is on the driver's side of the cab. Refer to the user manual to determine which fuse box contains the fuse for the brake light.
- You may need to remove the fuse box cover or interior trim to gain access to the fuse box.
- If you don't have the user manual, try visiting the vehicle manufacturer's website.
Step 2. Identify the brake light fuse
A broken brake light may be caused by a stuck lamp in the on or off position.
There may be more than one fuse for the brake light. If so, you should check one by one
Step 3. Remove the fuse and check for damage
Use sharp-edged pliers or plastic tongs to remove the fuse from the box. Look at the fuse if it has a clear receptacle. If the metal is damaged or burned inside the fuse, the component needs to be replaced.
- If you can't find the fuse inside, check for damage or burn marks on the tip.
- Most vehicle fuses have clear covers so you can see inside. If the cover itself is damaged so that the contents cannot be seen, the fuse is most likely damaged.
Step 4. Replace the damaged fuse with a new fuse of the same amperage rating
Find out how much amperage your brake lights need by looking at the chart. Most vehicle fuses use a current of 5-50 amperes, and the number is listed on the top of the fuse. Put the new fuse in the place of the old fuse in the box. If so, reinstall the box cover and any interior parts that were previously removed to gain access to the fuse.
- Reinstall the battery and start the vehicle.
- Have a friend stand at the back of the car to see if the brake lights are working properly.
