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Re: ABS brake troubleshooting Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Wed, 23 Jan 2008 06:04:06 In Reply to: ABS brake troubleshooting, Leif Åke, Tue, 22 Jan 2008 22:54:19 Members do not see ads below this line. - Help Keep This Site Online - Signup |
The ABS/Brake Fluid light coming on at startup can be normal. It is normal after the car has been sitting for a few hours. It is not normal if it happens after the car has been off for 15 minutes.
Rotors and pads won't affect the ABS. Brake pulsations at high speed braking is the sign of a warped rotor - it is possible a bad rotor was installed, or the wheel bolts aren't torqued evenly. But I have had new rotors with internal flaws which would start to pulse after getting warm. I think that is a different issue than the ABS light.
First, when was the last time the brake fluid was flushed? When was the last time the system was bled? If it has been a few years, do that first. Air in the system is a killer.
If the problem is still there after a flush/bleed, the next step is to check the accumulator (that's the black sphere). Open the hood and start the car. See that the brake fluid level in the reservoir goes down as the ABS pump runs (hums). The ABS and brake fluid lights will go out, but the pump will still run for a bit more. When the pump stops, see that the brake fluid level has dropped down to FULL. That is the correct FULL line.
Now, stomp on the brake pedal - fast stabs like you are trying to kill a spider on the pedal - bam bam bam. Count how many presses before the ABS and Brake Fluid lights come on. 12 or more is a good accumulator; 6-12 is marginal; 5 or less is a bad accumulator.
If it isn't air in the brake fluid or a bad accumulator, it may be a bad master cylinder. Not a happy thing, so do the easy stuff first.
posted by 192.249....
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