Intermittent Abs activation at low speeds

I have an 88 BMW 528E that intermittently activates the abs when coming to a stop at slow speeds. I did clean the sensors off and they look ok. Is there a way to verify which sensor is not working? I did not just want to start ordering $130 sensors trying to figure out which one is failing.
Thanks

Disconnect and check the resistance of each unit - it is a small coil similar to some CPS's. Also check the connections. Corrosion will upset things alot, as will slack sockets.

Might be a cracked O-ring

ok I opened the connections and checked resistance and all of them seem to work just fine. I see the resistance change as the wheel is rotated so they are seeing the notches. I did buy one new cable and changed the cable that had the most insulation pealing off and crumbling. Seems to be working ok but it has not been out in the rain yet. It is very intermittent. Some days no issue.

At least you know what it is not. Never going to be easy. Check loom wires if possible for damage of some type.

Thanks for the help. I will keep looking.

I had this issue in mine which was (is) caused by corrosion on the toothed pickup wheels on the front wheel hubs. The sensors do not receive an accurate tooth count and think the wheels are slipping when they are not.

Since replacing the front wheel hubs is both expensive and a PITA and I don't care too much about ABS I just disabled the whole system. I unplugged the ABS computer under the dash, turning it off all the time and removed the ABS light from the cluster. If my currently perfectly good wheel bearings ever fail I'll re-enable it but I don't care for replacing the parts just for the sake of the toothed wheel.
It's almost impossible to clean the wheels since the only access to them is through the hole that appears when you remove the ABS sensor.

Just something to think about. Your sensors may be fine but what they're reading could be the problem.