ASR control function - GF42.45-P-3500B

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)

ASR pressure build-up control mode

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

If one of the drive wheels tends to spin when starting off or accelerating, the control module introduces the ASR pressure build-up control mode.

At the start of ASR control the switchover solenoid valves (y18, y19) are switched to the "shut-off position" (closed) and the high-pressure/return pump (m1) is actuated.

The inlet solenoid valve (y23) is only opened during the pressure build-up phases, and the self-priming high-pressure/return pump (p1) draws brake fluid out of the reservoir via the inlet solenoid valve (y23) and via the master brake cylinder.

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

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

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ASR hold pressure control mode

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

The ASR hold pressure control mode starts if a more powerful brake intervention is no longer required to prevent drive slip.

The inlet solenoid valve (y23) is closed. As a result the pressure in the brake caliper cannot be increased via the high-pressure/return pump (p2).

Fig 2: Identifying ASR Control Function - ASR Hold Pressure Control Mode Circuit Diagram

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

ASR pressure reduction control mode

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

If the brake pressure required to prevent drive slip is too high, the ASR pressure reduction control mode starts.

The pressure reduction phase is introduced by opening the switchover solenoid valve (y19). The solenoid valve (y12) remains open and the solenoid valve (y13) closed.

The returning brake fluid flows back to the brake fluid reservoir via the high-pressure/return pump (p2) through the switchover solenoid valve (y19) via the master brake cylinder.

The self-priming high-pressure/return pump (p2) is also actuated in these control phases.

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

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

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