Mazda Training manual - part 87

Dynamic Driving Safety Systems 

ABS 

During Normal Braking 

• 

During normal braking, the solenoid valves are not energized. When the brake pedal is 
pressed, brake fluid pressure is built up by the master cylinder and passes through the 
inlet solenoid valves and then to the brake callipers. 

• 

The brake fluid pressure is fully controlled by the driver. When the brake pedal is 
released, the pressure decreases the opposite way it was built up.  

 

Inlet solenoid valve

Outlet solenoid valve

Pump motor

OFF (open)

OFF (closed)

OFF (stopped)

L2003_T02001

 

 

 

L2003_02005 

 

1 Master 

cylinder 

6 Reservoir 

2 

ABS HU/CM 

7 

Pump motor 

3 

Outlet solenoid valve 

8 

Pump 

4 Brake 

calliper 

9 Damper 

chamber 

5 

Inlet solenoid valve 

 

 

 

Curriculum Training 

02-7 

ABS 

Dynamic Driving Safety Systems 

During ABS Control 

• 

When wheel lock-up is about to occur, the system starts with the ABS control operation. 
ABS can operate three ways: 

– 

Pressure hold mode 

– 

Pressure reduction mode 

– 

Pressure increase mode (which is the same as the “Normal Braking” already 
explained on the previous page) 

 

Pressure Hold Mode 

• 

When the CM detects wheel slip increasing above a specified value, it holds constant 
the brake force applied to that wheel to avoid lock-up. 

• 

Therefore, it energises the corresponding inlet solenoid valve, closing the hydraulic 
circuit between the brake calliper and the brake master cylinder. Thus, the brake fluid 
pressure inside the related brake calliper cannot increase further. 

• 

Even if the driver presses the brake pedal further and the brake fluid pressure in the 
master cylinder increases, the brake pressure will not increase on a wheel that is 
currently in pressure hold mode. 

 

Inlet solenoid valve

Outlet solenoid valve

Pump motor

ON (closed)

OFF (closed)

OFF (stopped)

L2003_T02002

 

 

02-8 Curriculum 

Training 

Dynamic Driving Safety Systems 

ABS 

 

 

L2003_02006 

 

1 Master 

cylinder 

6 Reservoir 

2 

ABS HU/CM 

7 

Pump motor 

3 

Outlet solenoid valve 

8 

Pump 

4 Brake 

calliper 

9 Damper 

chamber 

5 

Inlet solenoid valve 

 

 

 
 

Curriculum Training 

02-9 

ABS 

Dynamic Driving Safety Systems 

Pressure Reduction Mode 

• 

When the CM detects that wheel slip is still increasing and reaches a specified value, it 
reduces the brake force applied to that wheel. 

• 

The inlet solenoid valve remains actuated and additionally the appropriate outlet 
solenoid valve and the pump motor are energised. Thus the brake fluid pressure in the 
brake calliper decreases and the released brake fluid is pumped from the reservoir 
towards the brake master cylinder. 

 

Inlet solenoid valve

Outlet solenoid valve

Pump motor

ON (closed)

ON (open)

ON (operating)

L2003_T02003

 

 

 

L2003_02007 

 

1 Master 

cylinder 

6 Reservoir 

2 

ABS HU/CM 

7 

Pump motor 

3 

Outlet solenoid valve 

8 

Pump 

4 Brake 

calliper 

9 Damper 

chamber 

5 

Inlet solenoid valve 

 

 

 
 

02-10 Curriculum 

Training