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

System Operation

System Diagram

E370020 *.sttxt { visibility: hidden; } *.stcallout { visibility: visible; } 1 VDM 2 RH Front Valve Solenoid 3 LH Rear Valve Solenoid 4 RH Rear Valve Solenoid 5 LH Front Height Sensor 6 PSCM 7 PCM 8 ABS 9 IPC 10 GWM 11 RCM 12 BCM 13 LH Front Valve Solenoid 14 RH Front Height Sensor 15 LH Rear Height Sensor 16 RH Rear Height Sensor 17 HVAC 18 IPMA

Item	Description
1	VDM
2	RH Front Valve Solenoid
3	LH Rear Valve Solenoid
4	RH Rear Valve Solenoid
5	LH Front Height Sensor
6	PSCM
7	PCM
8	ABS
9	IPC
10	GWM
11	RCM
12	BCM
13	LH Front Valve Solenoid
14	RH Front Height Sensor
15	LH Rear Height Sensor
16	RH Rear Height Sensor
17	HVAC
18	IPMA

Network Message Chart

  Module Network Input Messages - VDM

Broadcast Message	Originating Module	Message Purpose
ABS active	ABS module	Indicates the current ABS activity, on or off.
Accelerator pedal position	PCM	Indicates the current accelerator pedal position in percentage of travel with 0% at rest and 100% at full throttle.
Ambient air temperature	HVAC module	Indicates the current ambient air temperature in degrees Celsius.
Brake torque request	ABS module	This message indicates the total amount of braking, in newton meters, requested by the driver (via the brake pedal), the adaptive cruise control system or the collision avoidance system. The VDM adjusts the valve solenoids to help stabilize the vehicle during the operation of those systems.
Driven wheel torque request	PCM	Torque at the wheels (sum of all wheels) desired from the propulsion system. This includes the effects of the driver's accelerator pedal input and the effects of the virual driver functions, cruise control, adaptive cruise control.
Fuel level	IPC	This message is sent to the GWM and then to the VDM . Indicates the fuel level at time of ride height calibration in fractions of the fuel tank. The VDM uses fuel level when calculating suspension settings and uses a default setting when the information is not available.
Gear lever position	PCM	Indicates the current transmission gear status.
Gross train weight estimate	PCM	Rough estimate of the combined mass of a road vehicle, the passengers and cargo in the tow vehicle, plus the mass of the trailer and cargo in the trailer.
Ignition status	BCM	This message is sent to the GWM and then to the VDM . Indicates the current ignition status; off, accessory, run, start, invalid or unknown.
Life cycle mode	BCM	This message is sent to the GWM and then to the VDM . Indicates the current vehicle life cycle; normal, factory, not used or transport.
Odometer master value	IPC	This message is sent to the GWM and then to the VDM . Indicates the current odometer value in kilometers and whether the data is fresh or unchanged.
Power pack status	PCM	Indicates the current status of the engine and powertrain; Off - torque not available, On - torque not available, start in progress - torque not available or On - torque available.
Selectable Drive Modes mode request	ABS	Indicates the current SDM mode.
Stability control event in progress	ABS module	Indicates a stability control system (traction control or ESC ) is currently active.
Stability control indicator request	ABS module	Indicates the current stability control warning indicator status; on, off, slow flash or fast flash.
Stability control	ABS module	Indicates if ESC is available, yes or no, and active, yes or no.
Start stop status	PCM	Indicates the current start/stop status of the engine.
Steering angle data	PSCM	Indicates the current steering wheel angle relative to the straight ahead position.
Traction control	ABS module	Indicates the current traction control state, active or inactive and if it is active, yes or no.
Vehicle configuration data	BCM	This message is sent to the GWM and then to the VDM . Indicates the current vehicle configuration and optional equipment.
Vehicle lateral acceleration	ABS module	Indicates the current lateral acceleration of the vehicle in meters per second squared as measured by the sensors in the RCM and relayed by the ABS module.
Vehicle lateral acceleration	RCM	Indicates the current lateral acceleration of the vehicle in meters per second squared as measured by the sensors in the RCM .
Vehicle longitudinal acceleration	ABS module	Indicates the current longitudinal acceleration of the vehicle in meters per second squared as measured by the sensors in the RCM and relayed by the ABS module.
Vehicle longitudinal acceleration	RCM	Indicates the current longitudinal acceleration of the vehicle in meters per second squared as measured by the sensors in the RCM .
Vehicle roll rate	ABS module	Indicates the current roll rate of the vehicle in radians per second squared as measured by the sensors in the RCM and relayed by the ABS module.
Vehicle roll rate	RCM	Indicates the current roll rate of the vehicle in radians per second squared as measured by the sensors in the RCM .
Vehicle speed	PCM	Indicates the current vehicle speed in kilometers per hour.
Vehicle yaw stability index	ABS module	Indicates the current stability (oversteer or understeer) of the vehicle.
Vehicle yaw rate	ABS module	Indicates the current yaw rate of the vehicle in radians per second squared as measured by the sensors in the RCM .
Vehicle vertical acceleration	ABS module	Indicates the current vertical acceleration of the vehicle in meters per second squared as measured by the sensors in the RCM and relayed by the ABS module.
Vehicle vertical acceleration	RCM	Indicates the current vertical acceleration of the vehicle in meters per second squared as measured by the sensors in the RCM and relayed by the ABS module.
Vehicle yaw rate	RCM	Indicates the current yaw rate of the vehicle in radians per second squared as measured by the sensors in the RCM .

Vehicle Dynamic Suspension

The VDM is connected to the FD-CAN to communicate with other modules. The VDM also gathers suspension height information from the 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 maximum current the damping is more than when minimum 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 the minimum current.

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. It also checks for battery voltage above or below acceptable thresholds. Any malfunction detected in the above hardware of the system causes the VDM to set a DTC and send a message over the CAN to the IPC . The IPC responds by displaying a message in the message center and the VDM will deactivate the dynamic suspension system resulting in a firm suspension feel.

Component Description

Selectable Drive Modes (SDM)

The driver can select system modes using the (SDM) rotary dial. When a mode is selected, the VDM regulates the PWM signal to the valve solenoids to keep the suspension "feel" realtional to the selected mode.

Height Sensor

The height sensor sends 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 closed, resulting in a higher level of damping.

Vehicle Dynamics Control Module (VDM)

The VDM monitors all sensor inputs and all HS-CAN messages that relate to the vehicle dynamic suspension and then directly controls the valve solenoids. The VDM sends an individual electrical current to each valve solenoid to control the amount of damping required.

The VDM requires calibration when any of the following components is installed new, disassembled, disconnected or removed.

• VDM
• Suspension height sensor
• Front upper control arm
• Front coil over shock assembly
• Rear control arm
• Rear shock

The calibration procedure is carried out using the diagnostic scan tool and required for the system to learn the zero-position of the vehicle.

Before performing the calibration procedure:

• Be sure the vehicle is on a level surface.
• The vehicle must not be moving.
• No occupants in the vehicle.
• Make sure the suspension is in a neutral position if it was recently lowered. To neutralize the suspension, drive the vehicle a short distance, such as around a parking lot.