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Re: ABS light on C900 Posted by Ari [Email] ![]() ![]() In Reply to: ABS light on C900, Jason Carpenter, Tue, 11 Oct 2005 01:47:40 Members do not see ads below this line. - Help Keep This Site Online - Signup |
When you first start the car but don't drive off, the ABS and Brake fluid lights come on, and should go off.
If the ABS light doesn't go out, AND you haven't moved the car, then it is a failure of one of the self-tests on start up. The ABS system compares the resistance of each of the sensors, and if one sensor is out of whack with the others, it flags the problem.
If the light goes out, but comes on once you get moving, it's a different failure. The system looks at the signal coming from each sensor, and if they don't agree and it knows you aren't hitting the brake, it flags the problem. this can be due to a flakly sensor, or just crud buildup in the shutter wheel on the wheel hub. It looks like a gear, and if it gets filled with metallic crud (typical of semi-metallic brake pads, or just rotor wear), it won't read right.
With either failure, you can pay a shop to read out the faults, and it will tell you what the problem is, and which sensor. Or you can try stuff yourself.
With the first failure, First try reseating all the ABS connectors. One is the large 'harmonica' connector on the ABS box. (Kinda looks like a harmonica.) Next, pull apart and re-connect the individual ABS sensor connectors, up by the box - they look like pencil-thin cylinders with two pins. If that doesn't do it, measure the resistance (with a meter) of the sensor at that connector. I think it should be on the order of 1.2K ohms, +/- 200 ohms or so. If one sensor is totally whacked compared to the rest, that's the culprit. You can replace the sensor.
If it's the second failure (when driving off), clean all the pickup wheels.
Other than that, there are a bunch of other failures, but these two mentioned are by far the most common. The ABS box itself rarely fails.
posted by 192.249....
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