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Re: Light is ON! Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Thu, 6 Jun 2002 13:25:50
In Reply to: Light is ON!, Justin, Wed, 5 Jun 2002 13:56:11 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Two different issues here.
If the ABS light comes on after some stops, it probably is a sensor problem, but not for certain. The ABS does a lot of self-checking, and if it sees something wrong it will light the light, and the light will stay on until the car is shut off.
The ABS compares sensor inputs, and if they differ, it will light the light. BUT it could also be a caliper/brake problem. Just for example, assume one of your rear calipers is binding or sticking. You hit the brakes hard, and since all the weight is moving forward, that rear wheel starts to slip. The ABS will release the brake pressure on that wheel. But if the caliper is sticky, the brake is basically still on, and the wheel will still slip (not turn). The ABS will say 'hey, I unlocked that wheel but it still doesn't look like it's turning - light the light!'. Actually, it says 1101101, but close enough.
This can also happen with moderate braking over rough surfaces, like very bumpy asphalt.
So make sure your brakes are in good shape. Inspect the rears especially, because it can be easy to have a rear wheel slip and you won't know it. Signs of a sticky caliper are uneven brake pad wear, corrosion or rust on the rotor surface after you've driven the car (not cleaned off by braking). Jack up the wheel, and with the parking brake off, spin it. It should turn. Press the brake pedal hard a few times, and see if the wheel still spins freely. Heck, make sure the parking brake is releasing properly.
The dealer should be able to read out ABS codes. Either he's incompetent, or those particular codes get erased when the car is shut off. I won't judge, but I'd try and find another mechanic on that point.
As to the ABS and Brake Fluid lights. It is normal for those lights to stay on for a few seconds after the car is started. Those lights come on when the ABS pressure is low. This pressure drops when the car is sitting, and when you start the car, the ABS pump runs and repressurizes the system. The longer the car sits, the longer the pressure has to leak down, so the longer the lights stay on. It's not unusual to see Both lights on for up to 30 seconds after starting the car, if the car has been sitting overnight. The older the car, the longer it takes to get pressure up. Pretty much the same with most of us.
As long as both lights go out, and both lights stay out when driving, it's OK.
Old brake fluid tends to make for longer times, but not a guarantee. Brake fluid should be flushed every 2-3 years. Flushing the brakes will provide much better brake feel, extend the life of some very expensive parts, and may, as a secondary effect, make the lights go out faster. But if you don't know the last time the brake fluid was flushed, do it now. That old fluid contains water, which can lead to sticky calipers.
posted by 140.157.4...
, Thu, 6 Jun 2002 13:25:50 <-- Viewing This Message
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