GF32.50-P-4201RI ABC Front Axle/Rear Axle Valve Unit, Component Description

GF32.50-P-4201RI ABC front axle/rear axle valve unit, component description
- with CODE (487) Active body control (ABC)
- refinement package
- as of model year 09

Component Identification:

Location
The ABC front axle valve unit is located at left front next to the washer fluid reservoir.

Component Identification:

Location
The ABC rear axle valve unit is located on the left rear in the wheel well.

Design
The following valves and sensors are integrated into the front axle ABC valve unit:
- Left front suspension strut control valve (Y36/1y1)
- Left front suspension strut blocking valve (Y36/1y2)
- Right front suspension strut control valve (Y36/1y3)
- Right front suspension strut blocking valve (Y36/1y4)
- ABC pressure sensor
- Left front ABC pressure sensor
- Right front ABC pressure sensor

The following valves and sensors are integrated into the rear axle ABC valve unit:
- Left rear suspension strut control valve (Y36/2y1)
- Left rear suspension strut blocking valve (Y36/2y2)
- Right rear suspension strut control valve (Y36/2y3)
- Right rear suspension strut blocking valve (Y36/2y4)
- Left rear ABC pressure sensor
- Right rear ABC pressure sensor

Control valves
The control valves are used for adjustment of the hydraulic suspension struts and for oil flow regulation.

The control valves are designed as 3/3 directional control valves. To reduce leakage, the valves are equipped with a valve actuator cover at the center position. The valve is a linear motor valve which is closed when de-energized (center position of the double-spring-loaded valve actuator).

If the control valve is energized, oil is supplied to the suspension strut from the oil feed pressure circuit (suspension strut extends).

If, however, the flow direction of the electric current is changed, the valve actuator moves across the center position in the other direction and allows oil to flow back out of the respective suspension strut and into the return circuit. (suspension strut retracts).

The ABC control unit (N51/2) needs four current-controlled output stages in an H-bridge circuit to actuate the control valves. Current control is intended to reduce the power loss and is achieved by means of pulse-width-modulated (PWM) actuation.

An overload diode is fitted in the ABC control unit for the OFF phase of PWM actuation. The control valves can be deactivated redundantly if PWM actuation should fail.

Lock valves
The lock valves prevent the vehicle from being lowered or raised, when not in use, as a result of residual leakage of the control valves. The lock valves are closed in the de-energized condition. As the lock valves are permanently open in the normal mode (supplied with voltage), a current-controlled valve output stage is located in the ABC control unit to reduce the power loss.

When the lock valves are switched on (open) these are supplied with an increased current for a certain time.

The current is then reduced to the holding current. A redundant shutdown circuit is provided for the lock valves. The lock valves can also be shut down.

ABC pressure sensor
The ABC pressure sensor measures the current system pressure. This is required for pressure regulation and system monitoring.

ABC pressure sensors at front and rear
The ABC pressure sensors at front and rear determine the pressures in the suspension struts.