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ABS Lights and What They Mean

ABS light

An ABS light on your dashboard can be something simple or something deadly serious. Until you know for sure otherwise, always assume it's deadly serious. These are your brakes and they are the primary safety feature on your car. They should be treated accordingly. Every race car driver knows that going fast is great, but going fast without being able to slow down or stop is suicide.

Many drivers make the mistake of treating the light as a nuisance rather than a concern thanks to early ABS systems often having primitive sensors that would set off the light when exposed to water, mud, etc. Newer cars, however, do not tend to have this problem and the ABS warning lamp should be treated with concern. Here is what you should do should the ABS light come on and remain on.

Pull the ABS Error Codes

Start by pulling the codes on your ABS. Your ABSystem is controlled by a computer and when the lamp illuminates, it is indicating that an error code has been triggered, just as it would should this be an engine light. The ABS Control Module can be accessed through the vehicle's Power Control Module (PCM or "computer") on most vehicles.

Find out how to pull codes from your PCM/ABS here.

Often, once you have the codes, you can "reset" the computer (remove the code) and it may go back to normal. If after a few minutes the light comes back on, then you have an issue.

The ABS code will likely give you a good starting point for finding the problem. In addition to those diagnostics, though, you should also do the basics.

Start With the Easy Checks

Check the brake fluid levels and, if possible, the brake pad thicknesses. Make sure your vehicle doesn't have more than one brake fluid reservoir (some have one for the manual booster and another for the ABS pump) and if it does, be sure they're all filled to the full line. Make sure the fluid itself isn't bad and in need of flushing and replacement (this is a sign of worse problems).

Brake pads should be inside safety limits for thickness. If you aren't sure how thick they should be, take them to a professional. Brakes are too important to fool around with if you don't know what you're doing.

Check the Sensors

There are sensors on each wheel (usually a "speed sensor" and often a hub or "wobble" sensor, among other possibilities). There is also at least one sensor for the ABS pump (which automatically "pumps" the brakes in the "ABS stutter" that defines what this braking system does). There is also probably a fluid level/pressure sensor and could be others as well. Knowing which sensor is triggering the error goes a long way towards narrowing down the location of the problem.

Each of these sensors is on a circuit, which should also be checked. Begin with the ABS/PCM code and the sensor(s) associated and narrow down the possibility. Note that whatever triggers the code may not necessarily be the problem, just the first thing in line to notice it. So always check "ahead" of the sensor the code refers to.

Most of the time, ABS problems are bad sensors, bad sensor circuits, or a core problem with the brakes themselves.