That blue plug connects to the harness coming off the steering rack, for the Magnasteer.

You could also check the connectors at the hubs, sometimes the wiring gets chewed up a couple feet away from the connector.

Also check the connections at the ABS module and the BCM, black box behind the driver's side dash next to the door...

Outside of that, sounds like a bad ABS module, you can get them rebuilt for about 100 bucks online IIRC.