ESP control mode, function - GF42.45-P-3700B

MODEL 129 with ENGINE 112, 113 with CODE (472a) Electronic Stability Program (ESP)

MODEL 202 with ENGINE 112, 113, 604 with CODE (472a) Electronic Stability Program (ESP)

MODEL 208 with ENGINE 112, 113 with CODE (472a) Electronic Stability Program (ESP)

MODEL 210 with ENGINE 111, 112, 113, 604, 605, 606, 611, 612, 613 with CODE (472a) Electronic Stability Program (ESP)

MODEL 215, 220 with CODE (472a) Electronic Stability Program (ESP)

ESP pressure build-up control mode

The control process and valve positions shown in the example relate to the FR brake.

Fig 1: Identifying ESP Control Mode Function - ESP Pressure Build-Up Control Mode Circuit Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

A brake intervention to stabilize the vehicle is introduced by the ESP control module.

At the start of ESP control the switchover solenoid valves (y18 and y19) are switched to the "shut-off position" (closed) and the high pressure and return pump (m1) is actuated. The BAS solenoid valve (A7/7y1) in the brake booster (A7/7) is actuated (opened) from a speed of > 20 km/h (starting off range). Atmospheric pressure is led to the back of the diaphragms in the brake booster, generating pressure of approx. 5 bar in the brake circuits which is applied as pilot pressure at the suction side of the high pressure and return pumps.

The inlet solenoid valve (y22) is only opened during the pressure build-up phases. In the process the self-priming high pressure and return pump (p1) draws in brake fluid from the reservoir via the inlet solenoid valve (y22) and master brake cylinder.

The pressure limiting valve integrated in the switchover solenoid valve (y18) serves to limit high pressure (approx. 170 bar).

ESP pressure holding control mode

The control process and valve positions shown in the example relate to the FR brake.

The ESP pressure holding control mode starts if a major brake intervention is no longer required for stabilization.

The inlet solenoid valve (y22) is closed. As a result the pressure in the brake caliper cannot be increased via the high pressure and return pump (p1).

Fig 2: Identifying ESP Control Mode Function - ESP Pressure Holding Control Mode Circuit Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ESP pressure reduction control mode

The control process and valve positions shown in the example relate to the FR brake.

The ESP pressure reduction control mode starts if the brake pressure required for stabilization is too high.

The pressure reduction phase is introduced by opening the switchover solenoid valve (y18). The solenoid valve (y8) remains open and the solenoid valve (y9) remains closed.

The returning brake fluid flows back via the high pressure and return pump (p1) through the switchover solenoid valve (y18) to the brake fluid reservoir via the master brake cylinder.

The self-priming high pressure and return pump (p1) is also actuated in these control phases.

Fig 3: Identifying ESP Control Mode Function - ESP Pressure Reduction Control Mode Circuit Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

	ESP control module, location/task/function		GF42.45-P-4500B
	Traction systems hydraulic unit, location/task/design/function		GF42.50-P-4000B
	BAS solenoid valve, location/task/function		GF42.31-P-4002A