Circuit Description
The pressure switch (for low-pressure warning) monitors brake fluid pressure inside of the hydraulic brake booster (HBB). When the brake fluid pressure decreases abnormally, the pressure switch (for low-pressure warning) is turned off and the brake fluid low-pressure warning signal is output to the M-ASTC-ECU. The pressure switch (for pump motor control) monitors brake fluid pressure inside of the HBB. When the brake fluid pressure decreases lower than the specified value, the pressure switch (for pump motor control) is turned on and outputs the pump motor drive signal to the M-ASTC-ECU. The M-ASTC-ECU monitors an open circuit of the pressure switch (for pump motor control) (at terminal 11). The M-ASTC-ECU monitors an open circuit or short circuit of the pressure switch (for low pressure warning) (at terminal 57). See Fig 1 .