ABC front axle/rear axle valve unit, component description - GF32.50-P-4201SX

MODEL 216.3 up to Model Year 8

MODEL 221.0 /1 with CODE (487) Active Body Control (ABC) up to Model Year 8

Illustrated on model 221

Fig 1: Identifying ABC Front And Rear Axle Valve Unit

Courtesy of MERCEDES-BENZ USA

Location

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

The ABC rear axle valve unit is located at the top in the left rear wheelhouse.

Task

The ABC valve units control the functions of the Active Body Control (ABC) system by signals from the ABC control unit (N51/2).

Body

The following valves and sensors are integrated in the ABC front axle valve unit:

Left front suspension strut plunger valve (Y36/1 y1)
Left front suspension strut plunger check valve (Y36/1y2)
Right front suspension strut plunger valve (Y36/1y3)
Right front suspension strut plunger check valve (Y36/1y4)
ABC pressure sensor (B4/5)
Left front ABC pressure sensor (B4/8)
Right front ABC pressure sensor (B4/9)

The following valves and sensors are integrated in the ABC rear axle valve unit:

Left rear suspension strut plunger valve (Y36/2y1)
Left rear suspension strut plunger check valve (Y36/2y2)
Right rear suspension strut plunger valve (Y36/2y3)
Right rear suspension strut plunger check valve (Y36/2y4)
Left rear ABC pressure sensor (B4/10)
Right rear ABC pressure sensor (B4/11)

Function of plunger valves

The plunger valves are designed as 3/3 a directional control valve. The plunger valves are designed for leakage reduction with a valve slide overlap in the center position. Linear motor valves are concerned which are closed in the de-energized condition (center position of the dual spring-loaded slide). If the plunger valve is actuated, oil is supplied to the suspension strut from the oil supply pressure circuit (suspension strut extends). If the plunger valve is actuated in the reverse direction, then oil is lead out of the suspension strut into the return flow circuit (suspension strut moves in).

Function of plunger check valves

The plunger check valves are required for the safety concept. They prevent the vehicle from being lowered or raised when parked due to residual leakage of the plunger valves. The plunger check valves are closed in the de-energized condition. As the plunger check valves are permanently open in normal driving mode (supplied with voltage), a current-controlled valve output stage is located in the ABC control unit to reduce the power loss of the plunger check valves.

When the plunger check valves are switched on (open) these are supplied with an increased current for a certain time. After this the current is reduced to a hold-in winding voltage.