After brake switch & assembly replacements, brake lights stay on

The brake lights on my van are staying on. Twice, I have replaced the brake switch plus the brake assembly and switch. Each time I replaced those parts the car would perform well for only about two days. What is the problem that is causing the replacements to not keep working well after only two days? Thanks.
Experienced mechanics share their insights in answering this question :
Hello. This sounds like you may have a short in the wiring that goes to the brake light switch. I would recommend having a qualified professional use a digital multimeter to test the brake switch circuit for excess resistance. If the resistance in this circuit is out of specification, there is most likely a short in the wiring somewhere. Finding this short would require tracing the wires through the car and testing resistance in different locations to determine exactly where the short is located. Once the short is found, it may be repaired or the whole harness may require replacement depending on the extent of the damage.

How to Identify and Fix Common car Problems ?

Our sources include academic articles, blog posts, and personal essays from experienced mechanics :

The most common cause your brake lights stay on is because of a faulty brake light switch or sensor. It can also be caused by a faulty brake pedal or a malfunction in the electrical system. If you recently replaced the rear light bulbs when it occurred, you may have installed the wrong light bulbs.
You can see your brake light switch by looking under the dash, near the top of the brake pedal. The brake light switch is usually attached to a small bracket that holds the switch, activated when the pedal is depressed, in position.
The stop light switch (Fig. 22) is an air-signaled electrical switch which is turned on any time a brake application is made. The switch is usually connected to a double check valve and can be plumbed anywhere in the application side of the circuit.
The brake light switch on your vehicle serves an important safety function. When you press the brake pedal, it supplies power to the signal lights at the back of your vehicle to warn other drivers you have slowed.
Brake tail lights are the lights on the back of the car that turn on when you press the brake pedal. This is important for safe driving conditions because it provides specific notice to other drivers behind you when your speed is likely to change.
You only need a Brake-Lite Relay if you`re installing a supplemental towed vehicle braking system that pushes or pulls the brake pedal. With the engine off, step on your brakes. If the brake lights do not illuminate, you do not need a Brake-lite Relay.
A brake pedal position sensor is a device that detects the movement of the brake pedal in a vehicle. It is attached to the brake pedal lever underneath the dashboard. One job of the sensor is to turn on the brake lights to alert drivers to the rear of the vehicle whenever the driver presses the brake pedal.
Brake lights are available as LED or halogen, usually in P21/5W and P21W fittings.
Braking ratio is defined as the ratio of braking force against a car`s wheels to the car`s weight (Ref.
The control center for your car`s brake system is the master cylinder. At the most basic level, the master cylinder converts mechanical energy into hydraulic pressure that applies the brakes at all four wheels.
The brake fluid reservoir sits on top of the master cylinder. The reservoir has a sensor that triggers the brake warning light when the fluid level falls too low. On most cars, it is found directly in front of the driver`s side of the car.
The switch simply opens (off) or closes (on) the connection between the two terminals on the switch. When the switch is on, current flows along the black wire through the switch to the light, and then returns to ground through the white wire to complete the circuit.
The national cost for a brake pad wear sensor replacement in 2023 is between $19 and $148 with an average of $58.
Not every car is equipped with brake sensors, so to some this is still the only solution. For everyone else, this is the down and dirty on how brake sensors work. The brake sensor is normally attached to the brake pad itself.
The brake light switch sensor lets the ABS module in your car know when you`ve applied the brakes and indicates that it`s time to start the ABS hydraulic pump. That`s why if your ABS warning light comes on, there`s a chance that your faulty brake light switch is the culprit.
What color is brake fluid, or more importantly, what color is healthy brake fluid? Healthy brake fluid should be nearly clear with a yellow tint, which should be pretty close to the color it was in the bottle before you initially poured it into your car`s reservoir.
Also, called safety brake lamp or high-level brake lamp, the third brake light helps fellow drivers in knowing when you hit the brakes. It is useful when their view of the left and right brake lights is interrupted by other vehicles.
A third brake light provides an extra signal to distracted drivers—and studies confirm that it reduces automobile accidents.
A relay valve is an air-operated valve typically used in air brake systems to remotely control the brakes at the rear of a heavy truck or semi-trailer in a tractor-trailer combination.
Blown Fuse

If your lights don`t illuminate on either side and your brake light switch is good, then the next thing to check is the brake light fuse. Locate your vehicle`s fuse box, which is usually under the hood or on the kick panel inside the passenger compartment.

The brake light wiring system in most cars is not overly complex. At one end, you have the lights themselves: bulbs in sockets connected to a wiring harness. At the other end is the brake switch, where the pedal presses down and creates contact that completes the circuit. The system draws power from the car`s battery.
It`s super inexpensive to get a brake light bulb replacement done because a replacement bulb usually costs around $5-$10. Add to that the labor charge may be between $10-$20, depending on your locality. However, do remember the light bulb prices for some can be higher depending on their designs.
The most common method of testing brakes is to take the vehicle on the road, bring it up to speed, and then slam on the brakes! We can then measure stopping distance or use a decelerometer to measure the stopping forces created in %G.
On many cars, the brake pad can be seen through the wheel. Look at it to determine its thickness. If it seems very thin, less than ¼ inch, it is likely in need of replacement, according to J.D. Power. Some brake pads have a slot in the center that serves as a wear indicator.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

EPC light on 2004 Jetta. Code said brake switch faulty, but brakes lights worked. Replaced brake switch, now no brake lights.
ANSWER : Hi there. The first thing that pops in my mind beyond of what you have listed is perhaps the electrical harness attached to the brake switch. Perhaps the harness itself is damaged or you have an exposed wire, loose ground wire somewhere. You might want to have a professional mobile mechanic come to your location and complete a brake lights not working inspection to help you diagnose this issue.

I replaced the brake light switch. Gear lever unlocked because it had locked. Now the brakes feel hard.
ANSWER : Hi, thanks for writing in. You need to check the brake switch install adjustment. You may have the switch adjusted too tight and it is holding the the brake pedal partly down. This will cause the brake master cylinder to not release the brakes when you let off the pedal. Readjust the switch away from the pedal until you feel some free play again in the pedal. This should fix the problem. If you would like help, consider having an expert automotive technician from YourMechanic come to your home or office to inspect and diagnose this issue for you, and make or suggest any repairs as needed.

After brake switch & assembly replacements, brake lights stay on
ANSWER : Hello. This sounds like you may have a short in the wiring that goes to the brake light switch. I would recommend having a qualified professional use a digital multimeter to test the brake switch circuit for excess resistance. If the resistance in this circuit is out of specification, there is most likely a short in the wiring somewhere. Finding this short would require tracing the wires through the car and testing resistance in different locations to determine exactly where the short is located. Once the short is found, it may be repaired or the whole harness may require replacement depending on the extent of the damage.

Brake lights are not working. replaced brake light swtch still no brake lights. the third brake light the connection was melted at
ANSWER : The first thing to do is to repair third brake light and replace the brake light fuse and then see if the third brake lights work and the lower lights start working? If only the 3rd brake light starts working then you may need a further checks on the turn signal flasher or switch could be bad.

I have no brake lights and third brake light I have checked all fuses and brake pedal switch and the switch is fine and I’m still
ANSWER : Hi there. Well, you’ve listed most of the usual suspects including the brake switch, fuses and tail light assembly. However, one item you might want to also check is the accessory electrical relay. In some cases, the relay that supplies power from the brake switch to the tail light assembly will cause the issues you are describing. I always recommend that home mechanics purchase a service and repair manual for their vehicle to have a schematic accessibly, so it might benefit you to purchase one online to locate this relay or feel free to have one of our mobile mechanic some to your location and complete a brake light inspection, so they can help trace this issue for you.

When I put my foot on the brake my back left brake light goes off, when I take it off the brake the brake light comes on
ANSWER : I would suggest trying to disconnect and reconnect the wiring to the rear lights. I have seen these older Toyota vehicles rear lighting short out on the lights themselves due to the way the light circuit was made on the lamp housing. Look at the housing circuit on the light to see if one is touching another, and that could tell you why it is malfunctioning. There could also be a problem with the brake light switch. If you are not comfortable dealing with wires, I recommend getting in touch with a certified mechanic who can look at your brake light issue for you to see what’s going on.

Abs light, emergency brake light, steering wheel assist light, engine light, EPC light, traction control light
ANSWER : Hello, thank you for writing in. The vehicle does utilize a lot of the same sensors for these systems. Are there any other codes that are coming up when this code appears? If so you will want to take these into consideration when processing the repair and making a diagnosis. The module may be bad, and replacing it should fix the problem. The lights should turn off once the main computer recognizes the new module and the sensors sync up. If you believe the sensors need to be cleaned you may do so. Do as minimal as possible to make sure you are not damaging the sensor or disrupting the wiring inside. A bad connection would make the lights stay on. With so many lights that are effected by the module being illuminated, the module is likely bad or does not have a connection. Check the connection first and then resort to replacing the unit. For more help with these electrical tests, contact our service department.

Stuck in park no brake light I replaced brake light switch with no luck.Fuses good .Someone said their is another switch besides
ANSWER : You need to look to see if you are getting brake lights? If no lights even after replacing switch and checking fuses then you most likely have a broken wire at the brake light switch connector. Replace connector at brake light switch if you find the wire broke in connector by pulling on wire.