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Old 06-24-2005, 10:20 AM   #1
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Abs

My daughter has a '99 Saab and her ABS light came on. She went to a "friend" who works on cars that told her it will cost $2000 to fix. Can this be right? And if her brakes still work, what risk is there to drive without ABS?

Hope this isn't too off topic.


Last edited by slogans7; 06-24-2005 at 02:43 PM. Reason: capitalization!
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Old 06-24-2005, 11:27 AM   #2
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The brakes will still work fine, you just don't have the anti-lock feature. $2K sounds like a whole new system and it's usually not needed.

What did he look at to determine what needs to be replaced to come up with this figure?

First, here's how ABS works so you can figure out what the problem is. There are sensors on all of the wheels that are magnetic and they send signals to a central computer. Each wheel has teeth on the hub that rotate under the sensor as the wheel rotates. The sensor "feels" those teeth to determine if the wheel is moving or stopped and sends a signal to the central computer letting it know what's going on. If the sensor says the wheel has stopped, the computer checks the speed of the car to determine if it's a normal stop or if that wheel has locked up. If it determines the wheel has locked up, it sends a pulse signal to tell the system to let off of the pressure, then put it back on over and over so the car will stop faster and the wheels will not lock up.


There is something you can do that may help if you or someone you know can change brake pads. Dirty sensors are a common problem with ABS that will cause the light to sometimes come on. The sensors in each wheel are magnetic. Over the years your "semi-metallic" brake pads spray dust everywhere and some of that metallic dust gets down to the area of the the sensor. The magnet in the sensor collects the metallic dust. Eventually, the dust can collect to a point where the sensor cannot "feel" the teeth moving on the wheel any more. This causes the computer to see a problem because it is told the wheel is not moving, but the car is moving and the brakes are not applied. The computer thinks a sensor has gone bad so it shuts down the ABS system and flips the warning light on. To see if this is the problem, you an just pop the sensors out and clean them off. To get them out, take off the tire and look behind the brake caliper. You will see a wire going behind the caliper and into what looks like a cap about the size of a nickle. That cap is the top of the sensor. There is usually one screw holding it in. Remove the screw and GENTLY pull the sensor out. Don't pull on the wire and don't try to pry it out. If it's in there pretty tight, grab the cap and turn it back and forth a little to get it to come out. Make sure you don't twist much so you don't break the wire. Once it's out, clean the end with a shop towel and if it's stubborn, spray a little brake cleaner on the metal end. Try not to get the brake cleaner on the rubber parts. Put the sensor back in, screw it down and go to the other wheels.

If you try that and it doesn't work, let me know. There's a way to check each sensor to see if a wire is corroded but I would need to look up some specs specific to your car.
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Old 06-24-2005, 02:30 PM   #3
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Wow, thanks!

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