Brake light switch continuously fails

My brake light switch has failed more than five times in the past few months. It always seems to fail when the car is parked in the driveway and it is raining but not every time it rains. There seems to be no apparent correlation between switch longevity and weather patterns. I hit a deer over a year ago and replaced the front clip myself but had no issue for about a year. I have been all over looking for shorted wires and have been unsuccessful. Help please!

My car has 136000 miles.
My car has an automatic transmission.

Experienced mechanics share their insights in answering this question :
Hello. You may want to check the connections at the terminal as it is not uncommon for these to get very hot and melt the plastic inside and corrode. This may also be a rusty ground which can also cause the switch to short out when too much power is drawn. If you need some extra guidance by an expert, a certified professional from YourMechanic can come to your car’s location to diagnose your brake light problem and move forward with the appropriate repairs.

How to Identify and Fix Common car Problems ?

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

A bad brake light switch is typically caused by wear or damage to the switch itself, the wiring or connectors leading to the switch or the brake pedal mechanism that activates the switch.
Bad Switch: One common reason for the Parking Brake light to stay on is a failing or failed switch. This can be checked easily by jiggling the handle after it is down. If the light turns off (or turns off and then back on), the switch is the most likely culprit and will need to be replaced.
Pull up on the brake pedal and if the lights go out, switch mis-alignment or pedal position error is the likely cause. The final possibility is a wire shorted to power. Unplug the brake-light switch and if the lights stay on, a short circuit is the case. Finding such a shorted-circuit, is best left to a professional.
If one or more of your brake lights aren`t working properly, it could mean one of three things: The brake light system fuse is blown, the brake light bulbs are burned out or the brake light wiring switch is broken. All these issues are easy to troubleshoot.
The worst-case scenario for a brake-by-wire system is a complete loss of electrical power, but these systems typically maintain a backup hydraulic connection between the pedal and the brakes themselves. Even if everything powers down unexpectedly, the driver can still stomp the brake pedal and bring the car to a stop.
Brake System Warning Light

Indicates that the brake fluid level is low or the brake system is malfunctioning. This light also comes on when the parking brake is not released. If the light turns off after the parking brake is fully released, the system is operating normally.

Toyota`s Stop & Start Engine System monitors your brake pedal operation to stop your engine when you`re stopped. When your speed descends to 0 mph and you have depressed the brake pedal, the system stops the engine.
A P0504 code means that the engine control module has diagnosed a fault with the brake light switch signal control.
Learn how to test it and determine when to replace it. 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.
Place the sensor on just one of the two wires and hold the brake pedal down as you do so. Then test the other wire. If power is connected and the switch is working properly, the test bulbs will illuminate. If it doesn`t light up, the brake light switch is faulty and will need to be replaced.
The brake warning light comes on when there is a fault in the braking system, just like the check engine light comes on when there is an engine malfunction. The light warns the driver of an issue, but further investigation is needed to determine the cause of the problem.
The Light Control Module (LCM) is an important component of a vehicle because it controls all of the car`s lights, as well as the horn function.
The brake light system is a simple on and off exterior lighting system which is controlled by a brake light switch located near the top of the brake pedal. A simple wiring circuit is connected to the car`s BCM and then onto the rear brake lamps (older cars do not use a BCM – body control module).
The three main types of brake-by-wire systems are: electronic parking brakes which found widespread acceptance due to ease of implementation; electro-hydraulic brakes (EHB) which are compatible with, and easy to implement alongside, legacy hydraulic brakes; and electro-mechanical brakes (EMB).
The first wire is the ground wire, which is typically black. The second wire is the power wire, which is typically red. The third wire is the brake light wire, which is typically white.
On most vehicles, the tail lights are red and the brake lights are a more luminous red. Your rear lights also include back up lights, which are white.
A brake light switch is an electrical switch that turns your brake lights on when you hit the brakes. It`s an integral part of your braking system and lets the driver behind you know that you`re slowing down. It also has a direct influence on your ABS, cruise control system, and more.
If you have a modern car, you`ll have to look for two fuse boxes. Locate your brake light fuse with your car manual. Brake light problems can be caused by a blown fuse. If it`s blown, replace it with a new one.
Common Reasons Brake Lock Up

Using the wrong brake fluid. Damaged or broken parts (calipers, brake pads, pistons, rotors, or others) Defective ABS components. Broken parking brake.

Any loose, frayed, damaged, or otherwise faulty wiring in your tail light system will usually not affect your brake lights because they are powered by different wiring systems.
The brake switch B circuit allows the cruise control system to be disengaged by tapping the brake pedal, as well as ensuring that the torque converter lock-up system disengages when coming to a stop.
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.
A car with a faulty brake light switch is UNSAFE to drive. In most cars, the brake light switch is installed right above the brake pedal. Inside, it has a one- or two-way electric switch. The most common symptom of a faulty brake light switch is when brake lights don`t come on or stay on all the time.

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.

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.

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.

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.

Gear stuck on park. Brake lights dont turn on. Brake light switch has been changed the problem still remains.
ANSWER : Hello, thank you for writing in. The vehicle is likely having a connection issue somewhere around the switch. Since you have a voltmeter or test light, you will want to test for power leading up to the fuses, and then after the fuses. If you have power when pressing the light after the fuse (this means the power is making it through the fuse), continue to trace that voltage until you find where it stops. This voltage drop is most likely going to be at an electrical connection or terminal, a broken or frayed wire, a faulty switch, or a bad ground connection. Currently the vehicle is in a safety mode, and tracking down the cause of the brake light switch issue needs to be the main focus. For more help resolving the issue, contact our service department to schedule an appointment.

No dash lights, back right tail light is out, no parking lights. Brake lights work though as does head lights.
ANSWER : Hi there. In many cases, when you have electrical problems like you’re describing, it’s caused by multiple electrical component failure. It’s likely that a few electrical relays are not working; especially if you have systems that utilize the same components (such as your brake light and tail lights). I would recommend having a professional mobile mechanic come to your location to complete an electrical problems inspection first, so they can pinpoint what is damaged and recommend the right repairs.

Brake light does not work.
ANSWER : Use the power wire from the brake light switch to activate the rear brake lights. By having an alternate power supply, ;the brake lights have no control without a switch, so the module is on but not functioning for the brake lights on the rear of the car. If you need further assistance with your brake module, then seek out a professional, such as one from Your Mechanic, to help you.