Part 1

Vehicle Dynamic Suspension

Dynamic Suspension - Component Location

NOTE:
Right hand drive vehicle shown









OVERVIEW

NOTE:
This section covers the air suspension control system.
Front suspension, rear suspension, Dynamic Response and Terrain Response are detailed in separate sections. For additional information, refer to Front Suspension Locations
For additional information, refer to Rear Suspension Rear Suspension
For additional information, refer to Active Stabilization System Active Stabilization System
For additional information, refer to Ride and Handling Optimization Ride and Handling Optimization
The dynamic suspension system is a four corner air suspension system which is fitted as standard to all models.
The dynamic suspension system is electronically controlled by an air suspension control module which controls the air supply unit, reacts to inputs from four height sensors and distributes air around the system via valve blocks.
The main air suspension system components are:
- Air suspension control module
- Air supply unit
- Four height sensors
- Three valve block assemblies
- Reservoir
- Air harness
- Four suspension air spring damper modules.
The four corner air suspension system maintains the vehicle height under all operating conditions by controlling the mass of air in the air springs. The air suspension control module uses signals from the four height sensors to maintain the correct suspension height. This is achieved by operating pneumatic control valves to increase or decrease the mass of air in the air spring damper modules.
The air suspension system has three driver selectable, pre-determined ride heights. A driver interface indicates the selected ride height and direction of movement. Additional information is also relayed to the driver via the instrument cluster message centre and by audible warnings also transmitted by the instrument cluster.
Height changes can only be made when the engine is running and the driver's and passenger doors are closed.
Access height can be selected with the engine not running, within 40 seconds of moving the ignition switch to the off position provided the driver's door has not been opened in this time.
The air suspension can be controlled manually by the driver using a switch on the centre console to select the required height change.

Schematic Pneumatic Circuit









CONTROL DIAGRAM

NOTE:
A = Hardwired









OPERATING MODES

The driver can manually select, using the air suspension switch, one of four ride states:
- ON-ROAD - this height is the normal operating height of the vehicle
- OFF-ROAD - this height is higher than the on-road height and provides improved ground clearance, approach, departure and breakover angles
- ACCESS - this height is lower than the on-road height and makes entering and exiting the vehicle easier for the occupants
- CRAWL (Locked at access) - this height allows the vehicle to be driven at the access height at low speeds to provide increased roof clearance in low car parks etc.
HIGH SPEED - A non-selectable, automatic high speed mode is provided which lowers the vehicle height to improve vehicle handling.

NOTE:
Vehicle height changes are prevented if the air suspension control module receives a 'Door Open' signal from the Central Junction Box (CJB).
An additional 'TRANSPORTATION' mode is also available but is only selectable using a Land Rover approved diagnostic system.
An additional function allows the vehicle to be raised or lowered from outside of the vehicle when the vehicle is stationary. For example, this assists with the attachment of a trailer and is achieved using the buttons on the remote handset and the ignition switch in the off position. The remote handset can be programmed to perform a number of additional functions. For additional information, refer to Handles, Locks, Latches and Entry Systems
If the air suspension control module senses that the vehicle has grounded and lost traction, the control module can temporarily increase and/or redistribute the volume of air supplied to the affected air spring(s) to maximize the available traction. This is known as extended mode and will be indicated to the driver by the lamps on the air suspension switch flashing and a message in the instrument cluster message centre.
If the air suspension control module senses that the vehicle is prevented from moving upwards or downwards during a height change or levelling correction, the control module will adopt a safe state and further height changes will be suspended.
If a fault is detected by the air suspension control module, the control module will reduce the system functionality dependent on the type and severity of the fault. The control module will also store a fault code which can be retrieved using a Land Rover approved diagnostic system. If a severe fault occurs, the control module will attempt to put the vehicle in a safe condition. A fault is relayed to the driver by the illumination of the air suspension warning indicator, the instrument cluster message centre and an audible warning emitted from the instrument cluster.
If the detected fault is minor and does not affect vehicle safety, the air suspension warning indicator in the instrument cluster will illuminate in an amber color and the fault should be rectified at the earliest opportunity. If a more severe fault is detected, the warning indicator will illuminate in a red color at vehicle speeds above 31 mph (50 km/h) and the vehicle should be driven with care until the fault is rectified. An audible warning is emitted by the instrument cluster sounder when the warning indicator is illuminated. The indicator will change to an amber color and the audible warning will stop when the vehicle speed is reduced.

Air Suspension Switch Mode Lamps









On-Road Mode
This is the normal ride height for the vehicle.

Off-Road Mode
Off-road mode will only be activated if the vehicle speed is less than 25 mph (40 km/h). The vehicle will be raised 55 mm (2.2 in) higher than the on-road mode to provide additional body clearance and improved approach, departure and breakover angles. If the vehicle speed exceeds 31 mph (50 km/h), the air suspension control module will automatically lower the vehicle to the on-road mode height. At 25 to 28 mph (40 to 45 km/h) a message is displayed in the message centre to warn the driver to slow down or the vehicle will lower.

NOTE:
The suspension can be automatically set to off-road mode when some Terrain Response programs and low range are selected.


Access Mode
Access mode lowers the vehicle body height by 50 mm (2 in) and provides easier entry, exit and loading of the vehicle. Access mode can be pre-selected when the vehicle is moving. The vehicle will partly lower as the vehicle speed decreases, lowering to the full access mode height when the vehicle reaches 5 mph (8 km/h). If the required road speed is not reached within a predetermined time, the air suspension will return the vehicle to the previously selected height.
Access mode can be selected at any vehicle speed. When access mode is selected, the response of the air suspension system will depend on the vehicle speed:
- If the vehicle speed is more than 12.5 mph (20 km/h), the air suspension control module will wait for up to one minute for the vehicle speed to be reduced. The access mode lamp and the lowering lamp will flash while the air suspension control module waits for the vehicle speed to be reduced, the on-road mode lamp will remain illuminated. If the vehicle speed is not reduced sufficiently, the access mode request will be cancelled after 1 minute.
- If the vehicle speed is less than 12.5 mph (20 km/h), the air suspension control module will lower the suspension to a part lowered height and will remain at this height for up to one minute. The on-road mode lamp will extinguish as the air suspension control module lowers the suspension to the part lowered height. The access mode lamp and the lowering lamp will illuminate. When part lowered is reached, the lowering lamp will flash. If the vehicle speed is not reduced to less than 5 mph (8 km/h) in the one minute period, the access mode request will be cancelled.
- If the vehicle speed is less than 5 mph (8 km/h), the suspension will be lowered to access mode immediately. The access mode lamp and the lowering lamp will illuminate. When the access mode height is reached, the lowering lamp will be extinguished.
Access height may be selected up to 40 seconds after the ignition is turned off, provided that the driver's door has not been opened within this time.
The suspension will automatically rise from access mode when the vehicle speed exceeds 6.2 mph (10 km/h). If access mode was selected directly from off-road mode then the system will return to off-road mode when the vehicle speed exceeds 6.2 mph (10 km/h). Otherwise the system will lift the suspension to On-road height.
Selecting Access Mode Directly from Off-Road Mode
When the suspension is in off-road mode height, pressing the air suspension switch once and then a second time before the lowering lamp is extinguished, the control module will lower the suspension to access mode height. The control module will remember to return the suspension to off-road height automatically if the vehicle speed increases above 6.2 mph (10 km/h).

Crawl (Locked at Access) Mode
Crawl mode allows the vehicle to be driven at access height. The vehicle is locked in access height and can be selected at a speed of less than 21.7 mph (35 km/h) and can be driven at low speeds to improve clearance in areas with restricted headroom, i.e. car parks. If the vehicle exceeds 24.8 mph (40 km/h), crawl mode will be cancelled and the vehicle will return to on-road height.
Crawl mode allows the vehicle to be driven at low speeds with the suspension locked at the access mode height. This allows the vehicle to be driven in low car parks etc. with increased roof clearance.
Crawl mode can be selected from normal or access ride heights up to 21.7 mph (35 km/h) with a long press of the switch in the down direction. The access mode lamp and the crawl mode lamp will be illuminated. When the control module is in crawl mode, on-road mode height will be selected automatically if the vehicle speed exceeds 25 mph (40 km/h). At 18.6 to 21.7 mph (30 to 35 km/h) a message is displayed in the message centre to warn the driver to slow down or the vehicle will raise. Crawl mode can also be manually cancelled by moving the switch in the up direction for 1 second. The crawl mode lamp will be extinguished.

High Speed Mode
High speed mode is a non-selectable, automatic mode which lowers the vehicle height by 20mm to improve vehicle handling. This feature is fully automated and is 'invisible' to the driver.
If the vehicle speed exceeds 100 mph (160 km/h) for more than five seconds, the air suspension control module initiates the high speed mode. When the vehicle speed reduces to less than 80 mph (130 km/h) for more than 30 seconds, the vehicle returns to the On-Road height. This function is cancelled if a trailer is connected to the trailer socket.

Automatic Height Change Warnings
When the suspension is in off-road mode, access mode or crawl mode height, the air suspension control module will change the suspension height automatically when the vehicle speed exceeds predetermined thresholds.
When the suspension is at off-road mode or crawl mode height, the control module issues a warning to advise the driver that the vehicle is approaching the speed threshold. The instrument cluster sounder will emit a chime, a message will be displayed in the message centre and the on-road mode lamp and either the raising or lowering lamp will flash.
The off-road mode or crawl mode height speed warning is removed when the vehicle speed is reduced.