The pump shouldn't run continuously.
Is the car using the complete sierra ABS - loom, ECU, pump, solenoids, etc ? If so, there are not just 2 connectors - there should be a 5 way, a 2 way, another 2 way on the pump, a 3 way on the fluid level, and a 7 way on the (remote)(at least on sierras) solenoid block.