Modulator Unit: Notes
The modulator unit consists of the 4 inlet solenoid valves, four outlet solenoid valves, 2 front apply valves, 2 front dump valves, reservoir, relief valves, regulator valve, cut-off valve, pressure piston, Anti-Lock Brake System (ABS) pump, Vehicle Stability Assist (VSA) pump, and pump motor. The modulator controls the brake fluid pressure directly. It is a circulating-type modulator because the brake fluid circulates through the caliper, the reservoir, and the master cylinder. The hydraulic control has 3 modes: pressure intensifying, pressure retaining, and pressure reducing. The hydraulic circuit is an independent 4-channel type, one channel for each wheel. See Fig 1 .