Structure and inner electrical connection

The shift-position sensor and the two pressure sensors are supplied with current by the VDM control unit (initial current 0.35 ampere, maximum 2.5 ampere). The pressure control valves are activated by the VDM control unit with a pulse-width-modulated signal (5% to 95%). The direction valve as well as the safety valve are either energized or de-energized (activated or not activated).

Fig 1: Pressure Sensor - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Shift position sensor
2	Pressure sensor, front axle
3	Pressure sensor, rear axle
4	Front axle pressure control valve
5	Rear axle pressure control valve
6	Directional control valve
7	Safety valve

PIN REFERENCE

Item	Explanation
Terminal 31E	Terminal 31, electronics earth (ground)
PWM1	Activation of pressure control valve for front axle (pulse-width modulated)
PWM2	Activation of pressure control valve for rear axle (pulse-width modulated)
SI G1	Shift-position sensor signal
SI G2	Pressure sensor signal, front axle
SI G3	Pressure sensor signal, rear axle
SI G4	Activation signal for direction valve
SI G5	Activation signal for safety valve
5 V	Voltage supply Pressure sensor, front axle Pressure sensor, rear axle Shift position sensor

Setpoint values and signal path of pressure sensors

The signal for evaluation of hydraulic pressure depends on the pressure. The measuring range of approx. 0.5 - 4.5 Volts corresponds to a hydraulic pressure of 0 bar to 200 bar.

Fig 2: Characteristic Curve For Pressure Sensors On Front Axle And Rear Axle

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Signal voltage
2	Characteristic curve for pressure sensors on front axle and rear axle
3	Hydraulic pressure

Observe the following setpoint values for the components on the valve block:

Variable	Value
Supply voltage for pressure sensors and shift-position sensor	5 V
Pressure control valves, preliminary current applied	0.35 A
Response time of direction valve	approx. 30 ms
Maximum stabilization torque at the swivel motor (rear axle)	approx. 800 Nm
Delivery rate of tandem pump with suction throttle valve	5.2 to 9 l/min 3.0 l/min
Temperature range	-40 to 140 deg C

The suction throttle valve is connected by means of a 2-pin plug connection.

The suction throttle valve is a solenoid valve. The VDM control unit supplies the suction throttle valve with current (approx. 0.85 Ampere).

Fig 1: Suction Throttle Valve - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Suction throttle valve

PIN REFERENCE

Item	Explanation
12 V	Voltage supply for suction throttle valve
Terminal 31E	Terminal 31, electronics earth (ground) for suction throttle valve

The reed contact has the effect of a switch. If the reed contact is activated, ground is switched through to the VDM control unit.

Fig 1: Reed Contact Oil-Level Switch - Circuit Diagram

Courtesy of BMW OF NORTH AMERICA, INC.

Item	Explanation
1	Reed contact in the oil-level switch

PIN REFERENCE

Item	Explanation
SI G	Reed contact signal