All modern vehicles are equipped with an antilock brake system (ABS). The technology regulates brake fluid pressure to prevent wheel lockup during a panic stop or when stopping on slick surfaces.
A computer, called the ABS control module, is the heart of the ABS system. Although module failure is rather uncommon, it can happen, often resulting in one or more troublesome symptoms that you’ll want to address right away.
What is an ABS Module?
The ABS module is the computer that manages the ABS system. To better understand the module, it helps to be familiar with the design and function of the ABS system.
ABS System Operation
Since 2004, all new vehicles sold within the United States have been required to have ABS technology. The ABS system helps prevent wheel lockup and skidding, thereby improving steering control and minimizing stopping distance under most conditions.
Many different ABS system designs have been used in automotive applications over the years. But a typical layout includes the following components:
- A wheel speed sensor at each wheel
- A hydraulic control unit (which usually includes a pump motor and solenoid valves)
- An ABS control module (sometimes referred to as an electronic brake control module “EBCM” or electronic brake module “EBM”)
The ABS module monitors the wheel speed sensors to determine the deceleration rate of each wheel. When the sensors indicate wheel lockup is about to occur, the module operates the hydraulic control unit to pulse the flow of brake fluid to each wheel. The process reduces the braking contribution from the slipping wheel, allowing it to regain traction and avoid lockup.
The Role of the ABS Module in Other Systems
In addition, the ABS module helps manage the vehicle’s traction and stability control systems. To accomplish this task, the module adjusts brake operation to limit wheel spin and maintain the direction of travel.
The module also plays a role in regulating certain advanced driver assistance systems (automatic emergency braking, hill start assistance, etc.) on vehicles so equipped.
Symptoms of a Bad ABS Module
Do you think you might be dealing with a bad ABS module? If you notice one or more of the following symptoms, you might be right.
Note: Other problems can mimic a failed ABS module. You (or your mechanic) should perform a thorough diagnosis before conducting any repairs.
Illuminated Warning Lights
An illuminated ABS warning light is the most common sign of a bad ABS module. The stability control light, traction control light, and other warnings will also likely turn on.
ABS and Other Related Systems Don’t Work
Typically, a faulty ABS module will cause the ABS system to be disabled. As a result, you won’t have ABS functionality in situations where the system would usually kick in. Other related systems (traction control, stability control, etc.) might also be disabled.
Unintended ABS Application
A faulty ABS module can also result in unintended ABS application under normal driving conditions.
What Causes an ABS Module to Fail?
The ABS module can fail prematurely due to moisture, corrosion, and other external factors. Software glitches and normal wear can also lead to a module that needs to be reprogrammed or replaced.
Where is the ABS Control Module Located?
Typically, the ABS module is mounted to the hydraulic control unit, and the assembly is located in the engine compartment. However, the exact location will vary by vehicle, as some models have the module mounted separately or in a different place.
How to Test an ABS Module
Unfortunately, there isn’t a one-size-fits-all approach to testing an ABS module. But the troubleshooting process typically involves the following steps:
- Check for diagnostic trouble codes (DTCs): In most cases, a faulty ABS module will cause DTCs to set in one or more of the car’s control modules. Although DTCs don’t tell you exactly what’s wrong with a vehicle, they can be helpful as a starting point for further troubleshooting.
ABS-related DTCs can be retrieved with a capable scan tool or code reader. Keep in mind that not all diagnostic tools can access ABS codes, though, so you’ll want to do your homework before selecting a device.
- Perform a visual inspection: The next step is to perform a visual inspection. Look for obvious signs of damage, such as broken wires or poor connections. Fix any issues that you find, then re-check the vehicle for proper operation.
- Consult service information for the recommended diagnostic procedure: If nothing is found during the visual inspection, you’ll want to consult a repair database for the service information and recommended diagnostic procedure. A list of recommended resources can be found here.
Can I Drive with a Bad ABS Module?
Continuing to drive with a bad ABS module can compromise important systems, leading to reduced braking performance and other issues. You’ll want to address the problem as soon as possible to help keep your car safe.
Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic.