Part 3
DYNAMIC RESPONSE CONTROL MODULE
The Dynamic Response control module is located on the driver's side 'A' pillar, behind the instrument panel. The control module is secured to the vehicle body with two screws. Two connectors are located on the rear face of the control module and allow for the connection of the harness connectors. The two connectors supply power, ground, signal and sensor information to and from the control module for control of the Dynamic Response system.
On vehicles from 2007MY, the Dynamic Response control module contains 2 tunes- One for TdV6 and V8 petrol models and one for TdV8 models. When a replacement control module is fitted, the correct tune is selected from the data contained within the Car Configuration File (CCF) retained in the instrument cluster.
The Dynamic Response control module receives a power supply from the main relay via fuse 9E in the Battery Junction Box (BJB).
An engine speed signal is transmitted to the control module from the Engine Control Module (ECM) via the high speed Controller Area Network (CAN) bus. The engine speed signal is used by the Dynamic Response control module to detect that the engine is running and hydraulic pressure for the Dynamic Response system is available.
A road speed signal is transmitted to the control module from the ABS module on the high speed CAN. A steering angle signal is transmitted on the high speed CAN bus from the steering angle sensor. The Dynamic Response control module uses the road speed and steering angle signals to calculate lateral acceleration and for on and off-road roll compensation.
When reverse gear is selected and reverse wheel rotation is transmitted on the high speed CAN bus, the Dynamic Response system reverts to a 'locked bars' condition. This condition is maintained until reverse gear is deselected and a forward wheel rotation message is transmitted on the CAN bus.
The Dynamic Response control module receives an ignition on signal on the high speed CAN bus. The ignition signal provides an input into the control module to inform the control module that the ignition switch is in position 11. The control module initiates a 250 ms start time which is used to prevent functions operating when the software routines are being initialized.
When the ignition on CAN signal is removed, the control module senses that the ignition has been switched off. The control module remains powered for a 30 second period to allow fault information and adaptive values to be stored in the memory. The values and fault information are read by the control module when the ignition is next switched on. The power supply to the control module is maintained for as long as the main relay remains energized.
The Dynamic Response control module is connected on the high speed CAN bus to the diagnostic socket which allows diagnostic interrogation of the control module. The diagnostic socket allows for the connection of a Land Rover approved diagnostic system to read any stored fault codes in the control module. The control module can also be updated with revised software using a Land Rover approved diagnostic system should a software update be required.
When system faults are detected, the control module issues a message on the CAN bus which is received by the instrument cluster. The instrument cluster then illuminates the air suspension/Dynamic Response warning indicator as follows:
^ Minor faults - warning indicator illuminated in an amber color with an applicable message in the message center
^ Major faults - warning indicator illuminated in a flashing red color with an applicable message in the message center and an audible warning. The message will instruct the driver to stop the vehicle immediately or drive with caution.
Two messages relating to Dynamic Response are displayed in the instrument cluster message center:
^ SUSPENSION FAULT, VEHICLE LEAN, WHEN CORNERING
^ SUSPENSION FAULT, STOP SAFELY, STOP ENGINE.
The Dynamic Response control module supplies a control current to the Pressure Control Valve (PCV) in the valve block. The current supplied is determined by a number of input signals from the upper and lower accelerometers, road speed, steering angle etc.. The PCV controls the hydraulic pressure supplied to the actuators proportional to the current supplied by the control module.
Power is supplied to the two solenoid operated Directional Control Valves (DCV) in the valve block by the control module. Together, the two DCV's control the direction of flow of hydraulic fluid to the actuators. When the control module supplies power to the solenoids the valves open allowing hydraulic fluid to flow to the actuators. When power is removed, the DCV's close. DCV1 is left open for left hand corners and DCV2 is opened for right hand corners.
The pressure transducer located in the valve block receives a 5V current from the control module. The transducer measures the hydraulic pressures in the range of 0 to 180 bar (0 to 2610 lbf/in2) and returns a linear output voltage to the control module dependent on the hydraulic pressure.
The Dynamic Response control module supplies a 5V current to each of the accelerometers. Each accelerometer is capable of measuring lateral acceleration in the range of ± 1.11 g. An analogue input to the control module of between 0.5 and 4.5V relative to the lateral acceleration sensed is returned by each accelerometer. The control module processes the two signals received, together with the steering angle and vehicle speed signals, to produce a 'pure' lateral acceleration signal which is then used as the main control signal for the Dynamic Response system.
Failure Modes
Failures where the vehicle can still be driven safely are indicated by the air suspension/Dynamic Response warning indicator in the instrument cluster illuminating continuously in an amber color. The amber indicator will remain illuminated until the ignition is switched off. For all faults, the warning indicator will only illuminate again if the fault is still present.
Failures which require the driver to stop the vehicle immediately are indicated by the air suspension/Dynamic Response warning indicator flashing in a red color and an audible warning. This will also be accompanied by an applicable message displayed in the message center.
All faults are recorded by the control module and can be retrieved using a Land Rover approved diagnostic system. The diagnostic system provides a description of the fault, possible causes and corrective action to rectify the fault. The control module can fail to one of two states; 'locked bars' or 'reduced operation'.
The 'locked bars' condition means that pump flow is directed through the valve block and returns to the reservoir. Both DCV's close, trapping the fluid in the actuators. The fluid can flow from one actuator to the other via the valve block. The stabilizer bars will perform similar to a conventional stabilizer bar, resisting roll but still allowing suspension articulation.
The 'reduced operation' condition means that the system can still operate, but one of the input signals is not being received and so the system performance is not optimum.
If the steering angle sensor develops a fault or is out of calibration, there is a possibility that the dynamic response control module will record a fault code. A Land Rover approved diagnostic system should be used to check for fault codes and the adaptive data should be cleared by resetting the fault codes in the control module after the steering angle sensor has been recalibrated.
ACCELEROMETERS
Two accelerometers are used; an upper and a lower. Both accelerometers are identical in their construction.
The lower accelerometer is secured to the underside of the vehicle floor, on the RH inner sill panel, below the front door. The upper accelerometer is secured to a bracket on the body roof panel, in a central position at the top of the windscreen.
The lower accelerometer is the primary sensor used to measure lateral acceleration of the vehicle for roll control. The upper accelerometer is used by the Dynamic Response control module for roll correction and fault detection in conjunction with the lower accelerometer.
Each accelerometer is a capacitive acceleration sensor and operates on a 5V supply from the dynamic response control module. The upper and lower accelerometers can measure acceleration in the range of ±1.11 g and return an output to the control module of between 0.5 and 4.5V.
Failures of an accelerometer are recorded by the control module and can be retrieved using a Land Rover approved diagnostic system. A special tool is required to remove and replace the accelerometer in the mounting bracket.
HYDRAULIC CIRCUIT DIAGRAM
DYNAMIC RESPONSE SYSTEM OPERATION
Vehicle Not Moving
When the engine is running and the vehicle is not moving, both DCV's are closed, locking fluid in each side of the actuator piston. The hydraulic pump draws fluid from the reservoir and passes it at very low pressure to the valve block.
Because both DCV's are closed, after the fluid passes through the high pressure filter, it is directed through the PCV to the reservoir.
The PCV is open fully to allow the full flow to pass to the reservoir. The DCV's will remain closed until the control module detects a requirement to operate.
Vehicle Moving and Turning Left
When the vehicle is turning left, the accelerometers detect the cornering forces applied and transmit signals to the control module. The control module determines that an opposing force must be applied to the stabilizer bars to counter the cornering forces. The control module supplies a current to the solenoid of DCV2. Simultaneously, a current is supplied from the control module to the PCV which operates to restrict the flow of fluid returning to the reservoir.
The restriction causes the hydraulic pressure in the system to rise and the pressure is sensed by the pressure transducer which sends a signal to the control module. The control module determines from the inputs it receives what pressure is required and adjusts the pressure accordingly.
The pressure in the system is applied to the piston of each actuator, applying an opposing force to the stabilizer bar and minimizing the cornering effect on the vehicle and maintaining the vehicle attitude. The fluid displaced from the other side of the piston is returned to the reservoir via the valve block.
As the cornering force is removed when the vehicle straightens up, the control module opens the PCV to reduce the pressure in the system. The fluid bleeds from the actuator back into the system as the cornering force is reduced, removing the force applied to the stabilizer bar. When the vehicle is moving in a straight line DCV2 closes.
Vehicle Moving and Turning Right
When the vehicle is turning right, the accelerometers detect the cornering forces applied and transmit signals to the control module. The control module determines that an opposing force must be applied to the stabilizer bars to counter the cornering forces. The control module supplies a current to the solenoid of DCV1. Simultaneously, a current is supplied from the control module to the PCV which operates to restrict the flow of fluid through the bypass gallery.
The restriction causes the hydraulic pressure in the system to rise and the pressure is sensed by the pressure transducer which sends a signal corresponding to the pressure to the control module. The control module determines from the inputs it receives what pressure is required and adjusts the pressure control valve accordingly.
The pressure in the system is applied to the piston of each actuator, applying an opposing force to the stabilizer bar and minimizing the cornering effect on the vehicle and maintaining the vehicle attitude. The fluid displaced from the other side of the piston is returned to the reservoir via the valve block.
As the cornering force is removed when the vehicle straightens up, the control module opens the PCV to reduce the pressure in the system. The fluid bleeds from the actuator back into the system as the cornering force is reduced, removing the force applied to the stabilizer bar. When the vehicle is moving in a straight line DCV1 closes.
Vehicle Moving in a Straight Line
The control module is constantly monitoring the signals received and operates the DCV's and PCV to maintain the vehicle attitude when the vehicle is moving.
Off-Road Driving
Off-road detection is achieved by the control module by monitoring the signals from the upper and lower accelerometers for varying degrees of body movement. Off-road driving generates differing signals to the accelerometers which in turn produce differing outputs due to their vertical separation and the location of the roll center of the vehicle.
The two signals are passed through a filter to remove any offset caused by the vehicle leaning or the terrain. The control module then uses this signal to calculate the percentage of road roughness.
Below 25 mph (40 km/h) the percentage of road roughness calculated is used by the control module to limit the operation of the Dynamic Response system. At speeds above 25 mph (40 km/h) the system disables the percentage road roughness signal and full Dynamic Response system assistance is restored. The system is completely inoperative at speeds below 2 mph (3 km/h).
Side Slope Detection
The control module uses side slope detection when the upper and lower accelerometers detect an average acceleration of more than ± 0.2 g or 11 degrees of side slope and a road speed of less than 25 mph (40 km/h).
When side slope is detected, both DCV's close to provide a 'locked bars' condition. This condition increases stability and gives a constant vehicle response. As the road speed increases up to 25 mph (40 km/h), the level of average lateral acceleration must also increase and be maintained for the system to recognize that the vehicle is on a side slope. If the side slope angle is steep and the road speed is low, the control module will detect the side slope in a short time.
CONTROL DIAGRAM
NOTE: A = Hardwired; D = High speed CAN bus
