Fix Your ABS Light
Posted: Sunday, April 20, 2008
by Mark Gittelman
certifiedmastertech.com
If you're ABS light comes on the problem should be addressed. To many people drive around with this light on. Yes, you will still have regular brakes, but in an emergency situation your antilock brake system will not function as per design intent when the light is illuminated.
People have grown dependent on their antilock brake system. Before the ABS system came out we were all told in an emergency situation to pump the brake pedal manually to prevent lock up. When your wheels lock up you increase stopping distance as well as having less steering control. With the ABS system performing this function for us all that is now required is to jam the pedal as hard as you can and let the ABS system do its job by pulsing the brakes to stop the vehicle in the shortest distance possible.
On modern four-wheel antilock brake systems the ABS computer monitors wheel speed through four independent wheel speed sensors and compares that to the vehicles Main speed sensor, which is usually located in the transmission output shaft area, but can also be located on the rear differential.
When the computer sees a difference between the actual speed of the vehicle and an independent wheel. It begins to pulse the brake system through a computer-controlled brake modulator.
Common causes of ABS lights
If you have an ABS scan tool you can retrieve the code from the braking system computer that will point you directly to the malfunction area. My experience with diagnosing this system is that the individual wheel speed sensors are fragile and are easy to damage.
When I am diagnosing an ABS system, and I have retrieved a code for a wheel speed sensor failure, many times when examining the wheel speed sensor I find damage caused by road debris, ice and snow or other external forces that have damaged that particular wheel speed sensor or wiring connecting the sensor to the ABS module.
The repair or 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 very expensive.
ABS system diagnosis without the tool is very complicated and time-consuming. We all hope that the Government 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 wiring for signs of external damage. If you find a sensor or wiring broken you can replace this and then drive the vehicle to see if the light goes out.
If a code has been set by a failure of one-wheel speed sensors, when this sensor is replaced, the computer will automatically identify that the wheel speed sensor is now producing a signal and will extinguish the ABS light on its own.
Mark Gittelman is an auto repair expert and an ASE certified master mechanic. Mark supplies more free information about the latest development in affordable diy abs light diagnosis tools on his website. Mark also has a new video showing how you can fix your own car using online auto repair manuals.
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Top-level comments on this article: (2 total)excellent and detailed info, to bad that only dealers can really have access to such expensive tech.
Thank you. Now I know the fundamentals of ABS. Also, thanks for pointing out that we should get ABS, if not working, asap.
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