Emergency Brake Assist (EBA), or simply Brake Assist (BA), is a car safety system designed to decrease stopping distances in rapid braking situations.
If there’s a problem with the BA system or a supporting component, the message “Service Brake Assist” may display on the dash.
What causes the Service Brake Assist light to glow?
Here are the most plausible reasons why:
- Faulty sensor
- Old or low brake fluid
- ABS/TC/ESC malfunction
- Bad electronic control unit
- Brake booster problem
- Wiring or signal fault
This guide examines these causes further. We’ll also cover what to do if the Service Brake Assist light appears. Finally, we’ll explain how to reset the BA system after addressing the cause.
But first, a brief look at how Brake Assist works.
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How Does Emergency Brake Assist Work?
Simply put, if Brake Assist senses the brake pedal pressed with adequate speed and force, it increases hydraulic pressure to maximum. This means drivers need only press the pedal a short distance for full stopping power rather than all the way to the floor.
There are two principal types of BA systems, mechanical and electronic, though only the latter is still used today. Design specifics vary from one automaker to the next, but all work similarly.
Learn more about how Brake Assist works in this YouTube clip from The Engineer’s Post.
6 Causes For The Service Brake Assist Light Appearing
#1. Faulty Sensor
Brake Assist uses multiple sensors, which vary on the vehicle’s make and model. These measure hydraulic pressure, wheel rotational speed, and even the positions of the brake and accelerator pedals.
If a vital sensor fails, it can prompt the system to display a Service Brake Assist light on the dash.
#2. Old Or Low Brake Fluid
Once the Brake Assist system detects rapid braking, the master cylinder will pre-fill the brakes with hydraulic fluid.
Yet, if the car’s brake fluid is low, the system can struggle to build enough pressure. In this case, a Service Brake Assist light, or another indicator, may appear.
#3. ABS/TC/ESC Malfunction
Brake Assist functions with other safety features, like Traction Control (TC), Electronic Stability Control (ESC), ABS, and more. In fact, some even share the identical sensors to perform their particular operations.
A problem with one of these systems can baffle the ECU, possibly causing the Service Brake Assist light to illuminate.
#4. Bad Electronic Control Unit
Another reason for the Service Brake Assist light coming on is a faulty electronic control unit. Contemporary cars have 100+ ECUs managing their systems, including brake-related safety features like BA.
Further signs of a failing brake ECU include more dash alerts, the pedal getting tougher to press, or feeling spongy, among others.
#5. Brake Booster Problem
Brake boosters, also known as vacuum boosters or servos, “boost” braking performance by helping increase hydraulic pressure. This is achieved without the driver having to exert additional force.
A problem with one of the brake boosters, like a defective valve or vacuum leak, can lead to the Service Brake Assist light appearing.
#6. Wiring Or Signal Fault
As you may have noticed, Brake Assist is a bit intricate. The numerous components must communicate for the system to function.
An interruption, like a defective wire or fuse or a signal not transmitting, can result in the Service Brake Assist light appearing on the instrument panel.
Is It Safe To Drive With The Service Brake Assist Light On?
No, driving with the Service Brake Assist light on is never a wise idea.
Sure, it might seem like you have a minor issue with a passive, seldom-used safety feature. However, after learning the various causes, you can see that a Service Brake Assist warning can actually mean some substantial issues.
If you are uncertain about the reason the Service Brake Assist light is illuminated, you will need to either go to a shop or figure it out on your own.
How To Fix The Service Brake Assist Light
Check The Brake Fluid Level
Check the brake fluid level and state when you notice the Service Brake Assist alert.
Open the lid and add more if levels are below the minimum line. This might be all it takes for the dash alert to vanish.
If you can’t remember when you last changed your car’s brake fluid, or if it’s cloudy brown/black, you should consider flushing the system.
For the optimal results, most automakers suggest flushing the brakes every two years or 30,000 miles.
Scan The System For Errors
If your car’s brake fluid is fine, the next step is to scan the system for error codes using an OBD II scanner, which are small devices that plug into a car’s OBD port.
One error code, 01435, is associated with brake pressure sensor malfunction. There are numerous possible codes, like P0556 or P0577, which both concern brake booster problems.
Yet, diagnosing the issue is not the same as performing the repairs. If you aren’t proficient under a car’s hood, consider calling a mechanic for specific tasks.
Reset The Brake Assist System
If fluid levels are fine and a system scan reveals no problems, you should be able to safely make the light go away by resetting Brake Assist.
Resetting the light varies between manufacturers but disconnecting/reconnecting the battery is effective in most models. Just remember to drain the remaining power in between by repeatedly pressing the brake pedal.
Otherwise, check your vehicle’s owner’s handbook for directions on resetting Brake Assist.
What Should You Do If “Service Brake Assist” Appears On Your Car’s Dash?
It is vital to quickly deal with the reason behind a Service Brake Assist light for the sake of your vehicle, yourself, and your loved ones.
When safe, pull your car over and check the brake fluid levels. If below the minimum line, add more or call a tow truck.
For owners skilled with an OBD II scanner, finding the cause should be straightforward. Just be careful not to tackle a repair you don’t know how to execute.
If you don’t yet own a code scanner, you can find them for as low as $30 at any trustworthy online auto parts store.
