ESP control function ABS - GF42.45-P-3000A

MODEL 140 with CODE (472a) Electronic stability program (ESP)

MODEL 129 with ENGINE 104, 119, 120 with CODE (472a) Electronic stability program (ESP)

MODEL 210 with ENGINE 119 with CODE (472a) Electronic stability program (ESP)

Fig 1: Identifying ESP Control Function ABS

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Braking process in normal mode

ABS pressure build-up control mode

Every ABS control starts with a normal braking process which the driver performs via the brake pedal.

The ESP control module recognizes the braking process via the stop lamp switch and decelerated wheel speeds.

The brake pressure is built-up via the charging piston unit (14), the two switchover solenoid valves (y18 and y19) and the solenoid valves (y6, y8, y10 and y12).

This pressure build-up phase can take place individually at each wheel during the ABS control process.

The pressure is reduced via the same solenoid valves during a normal braking process.

Fig 2: Identifying Braking Process In Normal Mode

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ABS control mode - pressure holding

(The control process or valve positions shown in the example relate to the FR and RL brakes).

If a wheel tends to lock during the braking process, ABS prevents a further pressure build-up.

The ESP control module introduces the pressure-holding phase from the slip values of the wheels (FR and RL). The pressure-holding phase is achieved by actuating (closing) the pressure-holding solenoid valves (y8 and y10).

The pressure-reduction solenoid valves (y9 and y11) remain closed in this control phase.

Fig 3: Identifying ABS Control Mode - Pressure Holding Flow

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ABS control mode - pressure reduction

(The control process or valve positions shown in the example relate to the FR and RL brakes).

The ESP control module introduces the pressure-reduction phase from the slip values of the wheels (FR and RL).

The pressure-reduction phase is achieved by actuating (opening) the pressure-reduction solenoid valves (y9 and y11).The pressure-holding solenoid valves (y8 and y10) remain actuated (closed) in this control phase.

During the pressure-reduction phase brake fluid flows into the high-pressure/return pumps (p1 and p2) via the accumulator (11). The high-pressure/return pumps deliver the brake fluid from the brake calipers back into the brake circuits against the existing pressure.

	ESP control module, location/task/function		GF42.45-P-4500A
	Pressurizing piston unit, location/task/design/ function		GF42.45-P-4200A
	Traction systems hydraulic unit, location/task/design/function		GF42.50-P-4000A