Doc - Thanks for response.
The ABS system is all working correctly, both lights and its function.
The brake switch was replaced and it tests correctly, as did the old one, in doing specified function tests. At this point I suspect that the computer check that shows the brake switch as being defective is actually picking up a ECU malfunction in the part that receives the signal from the switch.
In talking to one company I was told that malfunctions in the ECU are only 300 per million so if this is true it is not a frequent problem. Know of any place that can test the ECU? Had thought of trying to find a used one but that may or may not be good.