My 2001 Silverado 4x4 has the ABS kicking on occasion on very slow stops for no apparent reason. Since this problem is intermittant, when I took it to a service center, the problem could not be duplicated by the technician. He did check the codes and it showed a DTC0281. (BRAKE SWITCH / STOP LAMP SW CIRCUIT) I am not certain if this code could be related to the problem I am experiencing.
Has anyone had a similar problem? Any help would be appreciated.
A common problem is that rust heaves the front wheel speed sensors away from the tone ring, this causes the speed signal (amplitude) to be different from one side to the other. The ABS computer uses both frequency and amplitude in making its speed determinations, hense, as one speed sensor is forced away from the tone ring, it produces a signal of different amplitude than one that is still positioned correctly. The repair is a matter of removing the brake caliper, the rotor, the backing plate, the speed sensor, then filing down the mounting surface where the speed sensor mounts until it is clean shiney metal again. The hole that the speed sensor slides into should be temporarily plugged while removing the rust build-up to avoid contaminating the bearing internals. A light application of a waterproof grease to the sensor mounting area to help ward off further corrosion is also recommended.
I had a similar problem with my 96 K1500 4x4 after owning it a couple of years. Problem was with the right front wheel connector for the ABS sensor. In my case, it was obvious as the bolts in the side posts of the battery were either too long or the hole too shallow from the factory causing acid to leak down the cable and drip right on that connector.. Anyway, you may just try to unplug and replug all of the connectors (not sure if this is 4wheel abs or not) and see if you find something obvious or the problem goes away.... I
C0281 indicates that an open or shorted brake switch circuit was detected when the vehicle either accelerated above 35 mph and slowed to a stop, or experienced an ABS event for 1 second. My guess is this is just a symptom of your problem, as if it is getting a false lockup indication it may also see this when the brakes are not even applied. Most likely you have a bad wheel speed sensor or one giving erratic readings due to rust on the tone ring, damaged wiring harness, etc.
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