Brakes not working
The car's brakes don't work.
Experienced mechanics share their insights in answering this question :
There are many reasons why brakes stop working. Low fluid level, leaking master cylinder, air in the lines, bad brake booster, etc. Since brakes are a safety concern, I suggest seeking out a professional to help you properly diagnose your brake issue in order to have the correct repairs done.
How to Identify and Fix Common car Problems ?
Our sources include academic articles, blog posts, and personal essays from experienced mechanics :
Air in the brake line(s) is the most common cause of a soft/spongy brake pedal. If air gets into the brake lines, it can prevent brake fluid from flowing properly, causing the brake pedal to feel spongy or soft. If the brakes are soft or spongy, this is a good time to change or flush the brake fluid.
The most common cause of failure is a leak in the brake lines. The brake fluid will slowly drain out, until there isn`t enough left to transmit the pressure from the pedal to the tires. The brakes can also fail when the discs or drums wear out, so they can no longer put enough friction on the wheels to stop them.
When brakes are not as responsive as what they should be, or if the brake pedal “sinks” down to the floor, this is a possible indication of a braking system leak. It could be a brake fluid leak, or a brake hose air leak.
Pressure Differential Switch
The valve/switch kicks in and blocks off pressure to that line, reserving pressure to either the front or rear brakes, allowing you to maintain one or the other so that you can safely come to a stop.
Air in the Lines: The number one most common cause for pumping your brakes to get them to work is air in the lines. This may be because your brakes were recently serviced but not bled correctly.
Brake Pedal Pulsation: Warped Brake Rotors
If the brake pedal pulsates and you can feel your vehicle shudder and shake when you press the pedal, that often indicates a problem with your vehicle`s brake rotors. On most modern cars, the brakes function by the caliper clamping down onto the brake rotors.
One of the most common reasons for your brakes touching the floor would be an issue with your brake fluid. Your fluid being low or air reaching the brake line will prevent the fluid from flowing properly, resulting in a spongy pedal. A bad brake booster is another common cause for a malfunctioning pedal.
The classic symptom of a failing master cylinder is a brake pedal that “dives” or sinks slowly to the floor while pedal pressure is being applied. Another sign to look out for is any leaks around the master cylinder. If a seal is worn out, it may leak past the seal and onto the pushrod that attaches to the brake pedal.
One common reason is a buildup of air in the brake lines, which usually means your vehicle`s brake fluid needs to be flushed. A lack of brake fluid due to a leak (often caused by rust) can also result in an unresponsive brake pedal.
Performing a Front to Rear Pressure Test
Place the gaugeʼs memory needles on zero. Start the vehicle. Apply the brake first using light to moderate force as if making a normal stop. Note the pressure readings, under this pedal force the front pressures should not be over 500psi in most vehicles.
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.
1) Line pressure can only be increased by either increasing the mechanical pedal ratio or by decreasing the master cylinder diameter. In either case the pedal travel will be increased. 2) Clamping force can only be increased either by increasing the line pressure or by increasing the diameter of the caliper piston(s).
Air in the System
The most common reason for a soft brake pedal is simply air still in the system. The easiest way to diagnose this problem is to pump the brake pedal gently a few times. In doing so, the pedal should become firmer with each gentle press of the pedal.
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.
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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.
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Low brake pedal and anti-lock brakes are not kicking in.
ANSWER : The brake pedal is working to stop the vehicle, but there may be air in the controller unit causing the ABS brakes to not function. I recommend bleeding the brake system from the farthest location from the master cylinder to the master cylinder including the ABS unit. If the brakes are still spongy after a full bleed, then the controller will need to be replaced. If you need further assistance with your brake pedal being spongy, then seek out a professional, such as one from Your Mechanic, to help you.
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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.
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Supportive bar attached to brake pedal interrupts proper braking process
ANSWER : It’s possible to have someone alter the brake pedal or adapt a brake pedal from a different vehicle. You may call around to some customization shops to see if anyone is interested in taking on the project. But first, I would try reaching out to the selling dealer with your concern – especially since it is a new model. Good luck.
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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.
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Okay so when I turn my lights on at night my brake lights do not work, when I don’t have my lights on they work fine.
ANSWER : Hi there. Based on your inquiry, it’s highly probable that you have a damaged light switch or some electrical fault inside the turn signal relay. However, it’s also possible that the brake switch above the brake pedal could also be the source of your problem. Due to the fact that multiple electrical components might be causing this issue, it’s a smart idea to first have a professional mobile mechanic complete a brake lights are not working inspection, so they can determine what’s causing all of these issues and recommend the right repairs.
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Brake lights on trunk not working
ANSWER : For some reason, when consulting the wiring diagram, I don’t see a trunk mounted brake light listed. I only see the high mount (one in the rear window) listed. Regardless, if the trunk bulb is not working with a new bulb, there is a problem with the circuit. Check for both power and ground at the bulb. Once you’ve determined which is lacking, you’ll have to trace the circuit to determine where the problem lies. Since you said all of the other brake lights work, the cruise control is likely unrelated. Electrical diagnosis can be difficult, so I suggest you have a trained professional tackle the problem with your brake lights for you.
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