Brake Light Comes On When Accelerating [Possible Causes and Fixes]

If your brake lights come on while driving and accelerating, you have to find the cause and fix it as soon as possible. Because it indicates issues with your braking system.

So, why does the brake light come on when accelerating? The reasons are as follows. 

• Your packing (emergency) brake is partially engaged
• Your car is low on brake fluid
• You may have a defective brake fluid sensor
• Your parking brake sensor is defective
• Your brake pads are worn out.

You must diagnose each of these possible culprits independently to know what caused the brake light to turn on when you press the pedal. Without more ado, let’s find out the reasons and get their solutions. 

What Causes Brake Light Comes On When Accelerating?

Properly functioning brake lights offer essential communication to motorists, increasing road safety. When the brake lights on your vehicle’s dashboard illuminate unexpectedly when accelerating, it understandably causes concern. 

Any indication that something may be awry with the braking system is a reason for scrutiny. It could interfere with the safe operation and control of the vehicle. The following are a few common culprits of the brake lights erroneously activating in such a situation.

Partially Engaged Parking Brake

A partially engaged parking brake is the #1 cause of this problem. Typically, the parking brake is a mechanically linked secondary braking system in most cars, especially the manual types. 

Even slight engagement activates brake pads against the rear braking surface. Friction builds heat, risking brake fade or damage. More critically, uneven braking disturbs vehicle stability and control.

Solution:

• Safely stop the vehicle in a safe location off the road. Once stopped, shift into the Park (automatic) or engage the parking brake (manual).
• Locate and manually disengage the parking brake lever or button. This will release the mechanical linkage.
• Inspect the brake pads and rotors for signs of heat damage before continuing to drive. Also, perform a complete parking brake system inspection as well.

Low Brake Fluid Level

Another common cause of the brake lights coming on during acceleration is low brake fluid. The brake master cylinder houses a sensor to monitor the brake fluid level. 

Brake fluid is essential to generate hydraulic pressure when brakes are applied. As the fluid level drops below the sensor’s threshold, it engages the brake light as a warning. 

Low fluid indicates leakage within the brake lines or calipers. This raises the pedal and reduces braking power progressively. Continuous driving risks total brake failure. Even minor leakage must be addressed.

Solution:

• Check the fluid level in the brake reservoir. There are two markings showing the maximum level and the lowest level. You want it in between the two marks. Also only add the specified type of brake fluid if below the minimum. 
• Clean the reservoir cap and surrounding area before removing it. Add fresh brake fluid until the level reaches the maximum mark. Do not overfill.
• Inspect brake lines and hoses for leaks or cracks that may be causing fluid loss. If you find any issue, replace the leaking.

Here is a video showing how to check for low brake fluid and how to refill it:

Defective Parking Brake Sensor

Similar to the fluid sensor, the parking brake sensor is calibrated to detect low-level engagement status. Electrical or mechanical degradation results in spurious signals not reflecting the parking brake’s actual position. Misreading full disengagement when it is partially engaged is hazardous.

Braking ability is compromised from unintended residual contact. Reliance on this safety backup becomes misplaced with a defective sensor. Only timely remediation can prevent potential accidents from flawed braking interaction data.

Solution:

• Inspect the parking brake cable and mechanism for worn, corroded, or damaged parts that could cause incorrect sensor readings. Replace any faulty components.
• Check electrical connections to the parking brake sensor for loose, corroded, or shorted wires. Clean contacts or repair/replace any problem wires.
• Calibrate the parking brake sensor according to manufacturer specifications. This resets the sensor’s baseline for engaged and disengaged readings.
• Replace the parking brake sensor with a new OEM or high-quality aftermarket sensor if inspection and calibration do not resolve inaccurate detection.

Worn Brake Pads

Brake pads grind rotors or drums to create friction for slowing and stopping the vehicle safely. Natural wear over time reduces pad thickness, diminishing braking force progressively. Before metal begins contacting braking surfaces, it indicates replacement needs.

Continued use risks overheating or lack of braking during emergencies. Low pads also change the interface mechanics, potentially confusing sensors regarding fluid volume or brake status. Replacement must occur when wear indicators reveal minimum specification.

Solution:

• Inspect brake pads and measure thickness. Replace if worn down to the wear indicator grooves or minimum specification.
• Remove old brake pads from the caliper assembly. This requires compressing or releasing the piston to create space for new pads.
• Install new brake pads with the correct specifications for your vehicle’s make and model. Insert pads fully so they sit properly in the caliper.
• Test drive the vehicle gently at first to allow brakes to bed in. Apply light to moderate braking force a few times to seat the new pads against the rotors or drums for full contact and performance. Avoid aggressive stops until fully bedded.

If none of the above solutions fix the brake lights coming on when accelerating, you need to take your car to a technician for a thorough checkup. It’s only through a complete scan and car inspection that you might find the underlying problem. 

Noticing your brake light turn on while accelerating can be quite unsettling for many drivers. While exploring this phenomenon, it’s also beneficial to be informed about other related brake light issues. One common problem that perplexes drivers is when the brake fluid light remains illuminated even though the fluid reservoir is filled to the appropriate level. Another peculiar behavior to be aware of is the intermittent flickering or activation of the brake light on the dashboard, where it toggles on and off. Knowledge about these varied symptoms can be crucial in ensuring your vehicle’s safety and maintaining optimal performance.

Frequently Asked Questions (FAQs)

Below are two common questions that many people with brake light comes on when accelerating problem are asking:

Conclusion

Driving with a brake light illuminated can lead to dire consequences. Therefore, it is essential to identify the cause for the brake light to come on while accelerating and address it quickly. 

Diagnosing each of these requires a close examination, and the repair process depends on the root cause. 

Most of the time, it comes down to appropriately inspecting the brake parts and replacing them as needed. If all else fails, it is recommended to take your vehicle to a technician for a thorough checkup.