If the ABS light comes on, a quick way to find out why is with an ABS scan tool. When the ABS system has a failure the electronic control module illuminates the warning light to notify the driver.
Diagnosis of this light is far different then the check engine light diagnostic procedure.
On modern four-wheel antilock brake systems the ABS computer monitors wheel speed through its independent wheel speed sensors and compares that to the vehicles Main speed sensor.
This car part is usually located in the transmission output shaft area, but can also be located on the rear differential on rear drive vehicles.
When the computer sees a difference between the physical speed of the vehicle and an independent wheel, it begins to pulse the brake system through a computer-controlled brake modulator.
ABS light problems
If you have your own inexpensive abs scan tools you can pull codes directly from the separate ABS computer. This will generally point you to the malfunction area.
My experience with diagnosing this Anti-lock system is that the wheel speed sensors are fragile and are easy to damage.
Often the abs codes that are set will be for a communication error from the wheel speed sensor. This means that the brake module is unable to see any wheel speed output at all.
If I have pulled a code for a wheel speed sensor failure, many times when I look at that sensor I find damage caused by ice, snow or other external forces such as road debris that has damaged that speed sensor or wiring connecting the sensor to the ABS system.
The replacement of an individual wheel speed sensor in most cases is very simple. The diagnosis of this system is also very simple if you have an ABS scan tool.
Unfortunately, this specialized tool is more expensive then the OBD scan tools which use the same basic technology.
ABS system diagnosis without the tool is very complicated and time-consuming.
We all hope that the Governments of the world will standardize the ABS diagnostic system just like they did with the check engine light diagnostics.
When you attempt your own DIY ABS diagnostics you can examine each wheel sensor and it’s wiring for signs of damage.
If you find a sensor or wires that are broken you can replace the assembly and then drive the vehicle to see if the light goes out.
The ABS system is a constant monitor system meaning the repair will be detected and the Abs light resets automatically. There is no manual reset or code clearing procedure.
In my humble opinion any time the airbag light, ABS warning light or check engine light comes on the car problem is worth looking into. Often I see motorists driving around with these safety system warning lights illuminated for extended periods of time.
These are critical vehicle safety systems that were deployed to protect passengers as well as drivers. Do not ignore these dash warnings or safety could be compromised for you and other people that share the road with you.
ABS scan tools
I have searched the Internet for cost-effective ABS scan tools and have found 2 that are worth looking at. See my report on cheap ABS scanners.