Lincoln Nautilus: Vehicle Dynamic Suspension / Vehicle Dynamic Suspension - System Operation and Component Description. Description and Operation

System Operation

System Diagram

Network Message Chart

  Module Network Input Messages - VDM

Vehicle Dynamic Suspension

The VDM is connected to the HS-CAN2 to communicate with other modules. The VDM also gathers suspension height information from 4 height sensors. With the information received, the VDM monitors the heave, roll, pitch, cornering, braking and acceleration of the vehicle. Based on this information the VDM calculates the best action for each valve solenoid.

Once the valve solenoid is energized, the damping increases with the PWM duty cycle. At minimum current the damping is less than when max current is applied. The damper and valve solenoid have been designed so failure leads to a firm ride. The fail-safe level of damping is at a level equivalent to what is produced at higher currents, but it is not the same as the maximum current.

The driver can select 1 of 3 preset system modes (Comfort, Normal or Sport) using the message center. When a mode is selected, the VDM regulates the PWM signal to the valve solenoids to keep the suspension "feel" relational to the selected mode.

When the VDM is initialized (ignition ON), the module carries out a preliminary electrical check of the height sensors, height sensor circuits, valve solenoids and valve solenoid circuits. Any malfunction detected in the system causes the VDM to set a DTC and send a message over the HS-CAN to the IPC . The IPC responds by displaying a message in the message center. Depending on the DTC present, the VDM may deactivate the dynamic suspension system resulting in a firm suspension feel.

Component Description

Vehicle Dynamics Control Module (VDM)

The VDM is the ECU for the vehicle dynamic suspension. The VDM monitors all sensor inputs and all HS-CAN2 messages relating to the vehicle dynamic suspension and then directly controls the valve solenoids.

When a new VDM is installed, the module must be programmed with the vehicle configuration information.
Refer to: Module Configuration (418-01 Module Configuration) .

When one of the following components is installed new, disassembled, disconnected or removed the VDM requires calibration.

• VDM
• Suspension height sensor
• Front lower control arm
• Front strut assembly
• Rear lower control arm
• Rear shock

The calibration procedure is required for the system to learn the zero-position of the vehicle which means the vehicle must be on a level surface, must not be moving and cannot contain any passengers or cargo. The calibration procedure is carried out using a diagnostic scan tool. The calibration routine should not be performed with the vehicle raised off the ground or immediately after lowering the vehicle as the suspension will not be in a neutral position. The suspension must be neutralized before performing the calibration routine by driving the vehicle for a short distance such as around a parking lot.

Height Sensor

The height sensor uses a potentiometer to send a variable amount of voltage back to the VDM based on suspension height. The sensor has 3 circuits, one circuit is for the 5 volt sensor supply, one circuit is for sensor ground and one circuit is for the sensor output.

Valve Solenoid

The VDM uses a PWM output to control the valve solenoid. The solenoid opens or closes the valve depending on the amount of current supplied by the VDM . The higher the current, the more the valve is opened, resulting in a higher level of damping.