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

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 Mode Function - ESP Control Mode - Pressure Build-Up Circuit Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ESP control mode - pressure build-up

(The control process or valve positions shown in the example relate to the FL brake).

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

At the start of ESP control the front axle switchover solenoid valve (y18) and the solenoid valve (hold) (y8) are closed.

The ASR/ESP charging pump (M15) charges the high pressure and return pump (p1) with 3 - 15 bar via the pressurizing piston unit (14) and the front axle precharge solenoid valve (y16).

The pressure produced by the high pressure and return pump (p1) is led to the FL wheel brake via the opened solenoid valve (hold) (y6).

The pressure limiting valve integrated in the front axle switchover solenoid valve (y18) is required to limit high pressure (approx. 170bar).

The pilot pressure is also applied to the actuated (closed) rear axle solenoid valves (hold) (y10 and y12) via the opened rear axle switchover solenoid valve (y19)

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

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ESP pressure holding control mode

(The control process or valve positions shown in the example relate to the FL brake).

The pressure holding phase is introduced by actuating (closing) the solenoid valve (hold) (y6). The solenoid valve (release) (y7) remains closed in this control phase.

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

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ESP pressure reduction control mode

(The control process/valve positions shown in the example relate to the FL brake).

The pressure reduction phase is introduced by actuating (opening) the solenoid valve (release) (y7). The pressure solenoid valve (hold) (y6) remains closed. The ASR/ESP charging pump (M15) and high pressure and return pump (p1) are also actuated in this control phase. The switchover solenoid valve (y18) is closed and the precharge solenoid valve (y16) is open.

The brake fluid flows back into the precharge pressure circuit via the opened precharge solenoid valve (y16).

The brake fluid delivered which is delivered back from the high pressure and return pump (p1) at the same time is also led back into the front axle precharge pressure circuit through the pressure limiting valve (170 bar) integrated in the switchover solenoid valve (y18).

	ESP control module, location/task/function		GF42.45-P-4500A
	ASR/ESP charging pump, location/task/design		GF42.45-P-4100A
	Pressurizing piston unit, location/task/design/function		GF42.45-P-4200A
	Traction systems hydraulic unit, location/task/design/function		GF42.50-P-4000A