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

MODEL 163 as of 1.9.02 with CODE (472) Electronic Stability Program (ESP) 

MODEL 170 with ENGINE 111,112 with CODE (472) Electronic Stability Program (ESP) 

MODEL 202 with ENGINE 111, 605, 611 with CODE (472) Electronic Stability Program (ESP) 

MODEL 203 with CODE (472) Electronic Stability Program (ESP) 

MODEL 208 with ENGINE 111 with CODE (472) Electronic Stability Program (ESP) 

MODEL 209 with CODE (472) Electronic Stability Program (ESP) 

Shown using model 209 as an example 

ESP control mode, pressure build-up 

The control procedure and value positions illustrated in the example refer to the FR  brake. A brake intervention to stabilize the vehicle is introduced by the < > front right < > wheel by the ESP and BAS control unit (N47-5)

In normal operation at the start of the ESP control the right front solenoid valve (pressure hold) (y8) is opened, the front axle switchover solenoid valve (y18) is switched into the "Lock position" (closed) and the front axle pump (p1) is actuated.

The front axle inlet solenoid valve (y22) is only opened during the pressure buildup phases.

In the process the front axle pump VA (p1) draws brake fluid out of the reservoir via the inlet solenoid valve (y22) and via the master brake cylinder and prepares high pressure for introduction into the corresponding wheel brake.

If extremely rapid stabilizing action is required, the pressure build-up phase is boosted by active actuation of the Brake Assist system. This directs atmospheric pressure against the rear of the diaphragms in the brake booster, producing a pressure of approx. 5 bar in the brake circuits.

The pilot pressure thus produced is lead via the check valve (7) from the front axle switchover solenoid valve (y18) into the active brake circuit to the right front  brake caliper until the pressure downstream of the check valve (7) is higher than the primary pressure.

At the same time the pilot pressure is applied via the front axle inlet solenoid valve VA (y22) to the intake side of the front axle pump (p1) and improves its fill level and delivery rate. The pilot pressure is kept away from the inactive wheel brakes by closing the solenoid valves (y6, y10, y12).

The pressure limiting valve integrated in the rear axle switchover solenoid valve (y19) serves high-pressure limitation. The valve opens at pressure valves > 150 bar.

Shown using model 209 as an example 

ESP control mode, pressure hold 

The control procedure and value positions illustrated in the example refer to the FR  brake.

When no more severe brake intervention is required to stabilize the vehicle, the ESP pressure hold control mode commences.

The front axle inlet solenoid valve (y22) and right front solenoid valve (pressure hold) (y8). As a result the pressure in the brake caliper cannot be increased via the front axle pump (p1).

Shown using model 209 as an example 

ESP control mode, pressure reduction 

The control sequence and valve positions described in the example refer to the right front  brake.

If the brake pressure required to stabilize the vehicle is too high, the ESP pressure reduction control mode commences.

The pressure reduction phase is introduced by the opening of the right front solenoid valve (pressure release) (y9). The right front solenoid valve (pressure hold) (y8) remains closed.

The brake fluid flowing back returns via the front axle pump (p1) through the pressure limiting valve integrated in the front axle switchover solenoid valve (y18) via the master brake cylinder to the brake fluid reservoir.

The rear axle pump (p2) is actuated pulsed during all control phases (depending on the requirement).

Various damping components (12, 13, 14) are installed to further reduce noise levels.

	ESP control unit, location/task/function	Model 163 Applicable as of 9/02	GF42.45-P-4500M
		Model 170, 202, 208 Model 203 up to 7/01	GF42.45-P-4500C
		Model 203 from 8/01 Model 209	GF42.45-P-4500T
	Traction systems hydraulic unit, location/task/ design/function		GF42.50-P-4000D
	Location/task/function of BAS solenoid valve		GF42.31-P-4002A