Ride Height Tolerance Control

The CHCM has two ride height tolerance bands: normal tolerance and tight tolerance.

The control module considers the vehicle to be at target height if the current height is within the appropriate tolerance band. Height adjustments are not made until the vehicle height falls outside of the tolerance band for a pre-determined time. The time period is different depending on if the vehicle is moving or stationary. The tolerance bands are as follows:

Normal ± 9 mm
Tight ± 3 mm.

The tight tolerance band is only used in the following conditions:

if set by the Land Rover approved diagnostic system for diagnostic purposes or by manual activation sequence.
when the vehicle has been stationary for more than 15 minutes.
when the following procedure is applied:
1. Start the engine.
2. Set the suspension to Normal height.
3. After ensuring all doors are closed, open the driver's door
4. Depress the brake pedal lightly three times in quick succession.
5. Close the driver's door within 10 seconds of the first brake pedal depress.

If the procedure has been successful the instrument pack will emit two soft chimes about 1 second after the driver's door is closed. Thereafter the instrument pack will emit two soft chimes each time the driver's door is closed to confirm that tight tolerance mode is still active.

This tight tolerance mode will be cancelled when the engine is turned off or the vehicle speed exceeds 8 km/h (5 mph).

The driver can manually select, using the air suspension switch, one of four ride states:

NORMAL - this height is the normal operating height of the vehicle.
OFF-ROAD - this is higher than the on-road height and provides improved ground clearance, approach, departure and break-over angles up to speeds of 80 km/h (50 mph).
ACCESS - this height is lower than the on-road height and makes entering and exiting the vehicle easier for the occupants.
Locked at access - this allows the vehicle to be driven at the access height at speeds up to 40 km/h (25 mph) to provide increased roof clearance in low car parks, for example.

Vehicle height changes are restricted if the CHCM receives a 'Door Open' signal and the speed is less than 8 km/h (5 mph).

NOTE: Refer to the Door Open Functionality information, for height change restrictions.

A complete vehicle delivery mode is available but is only selectable using the Land Rover approved diagnostic system. When this mode is active most vehicle systems, in addition to the air suspension, are inhibited or restricted to a minimal functionality. In this mode the air suspension is set to the transportation mode.

If the CHCM senses that the vehicle has grounded and lost traction, the control module can temporarily increase the volume of air supplied to the air springs 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 an 'EXTENDED MODE' message being displayed in the instrument cluster.

If a fault is detected by the CHCM, 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 the 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 instrument cluster message center and an audible warning emitted from the instrument cluster.

All information messages will be displayed for four seconds.