WARNING: This page is about a different car, the 2006 Toyota Corolla and 2005 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
This solenoid goes on when signals are received from the ECU and controls the pressure acting on the wheel cylinders to control the braking force.
Fig 1: DTC C0226/21, C0236/22, C0246/23, C0256/24 And C1225/25 Problem Diagnostic Chart