Didnt the snap on scanner give you an abs code for brake switch intermittent failure? Its already been diagnosed, the ABS computer did it for you. I reckon it could be a pushed pin in the connector, wiring harness defect but odds are its just normal wear and tear on the brake switch. How are you going to catch a intermittent problem with a multimeter? Think you can fit someone under your dash while you are driving and taking measurements when you yell "hey, its doing that thing again!"? The brake switch isnt expensive. Replace it and rule it out. Keep slipping that converter like you are and your parts cannon will be buying a converter isntead of just a brake switch!