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Why Does a Cars Brake Warning Light Come on and Then Go Off While Driving?
Why Does a Car's Brake Warning Light Come on and Then Go Off While Driving?
Have you ever experienced a brake warning light in your car that seems to comes on and then goes off while driving? If so, you might be wondering what's causing this. In this article, we'll explore common reasons for this issue, particularly in vehicles like the BMW with an early system. We'll also provide steps on how to diagnose and potentially fix the problem.
Common Causes of the Brake Warning Light Behaving this Way
For a car like your father's BMW, the brake warning light coming on after starting and then going off is typically a signal that the car is performing an internal check on the brake lights. This is often done before the first use of the brakes to ensure they are functioning properly. If the brake lights are working correctly, the light will reset.
Possible Fault in Components
However, the brake warning light may also indicate an issue with the master cylinder or brake booster. Both of these components are critical for your car's braking system. If you encounter a problem with these parts, it's essential to address it as soon as possible. A mechanic or an experienced amateur can usually diagnose and resolve the issue easily.
Understanding Brake Lights and Their Function
It's important to note that brake lights do not stop your car. The actual stopping is determined by the brake pads and brake discs or rotors. Brake lights are activated by a pressure switch that engages when you step on the brake pedal. Naturally, like any other electronic component, brake lights can malfunction and fail to turn on or off as expected.
When such issues occur, it's where you might want to start your diagnosis. Often, a malfunctioning brake light can be related to electrical components, and if that's the case, this is where you should begin looking.
Reasons for a Brake Fluid Level Warning
One frequent reason for this phenomenon is a low brake fluid level. Brake fluid is a crucial component of the braking system, and it's designed to maintain a specific level within the system. The fluid level can fluctuate slightly as the car moves, and if the fluid goes below the minimum sensor level, the warning light will turn on. Conversely, when the level returns to above the minimum sensor level, the light will turn off.
Checking and Servicing Your Brake Fluid
To check the brake fluid level, first, ensure that your brakes are functioning properly. If you're not comfortable working on your car yourself, it's a good idea to have a professional mechanic inspect it. However, if you know your brakes are still working, you can perform a few checks and services yourself.
Identifying and Fixing Low Brake Fluid
Brake fluid is contained in an airtight system to prevent moisture from mixing with it. Moisture can degrade brake fluid, leading to a buildup of mud and muck, which you might notice underneath the reservoir cap. Over time, the fluid can also get low as brake pads wear down, requiring a fluid top-up. If the brake fluid level was never corrected and you decide to add some, make sure it blinks when you make sudden changes in the car's attitude. Otherwise, check for a potential brake fluid leak, which can be extremely serious.
Brake Fluid Bleeding Process
When bleeding brake fluid, always start by checking the fluid level. If needed, add fluid to bring it back to the appropriate level. Ideally, you should push brake caliper pistons to squeeze the old fluid and then replace it with clean fluid. To achieve this, you can use a vacuum tool to pull out any air from the master cylinder reservoir and use clean, fresh brake fluid.
Additional Steps and Considerations
Some anti-lock brake systems (ABS) require a scan tool to bleed the system correctly. It's crucial to never run the system completely out of fluid, as this can introduce air into the ABS actuator, which can interfere with the performance and safety of your braking system.
In summary, the brake warning light coming on and then going off while driving can be due to several reasons, including malfunctioning brake lights or low brake fluid levels. Regular checks and maintenance of your brake system can help you address these issues before they become more severe.