Rear suspension (Operation): Description and operation (page 2 of 3)

Normal ride height When the vehicle is stationary, a door is open and the ignition is off, the SLS system will allow the rear of the vehicle to lower to within 20 mm of the normal ride height as load is removed from the vehicle. The SLS system will only operate the compressor to raise the rear of the vehicle when the engine is running, unless requested using the remote handset.

Off-road mode (ORM) ORM is used to raise the rear of the vehicle from normal ride height to the ORM ride height of 100 mm between the tip of the bump stop and the axle.

ORM is activated by depressing the ORM switch located on the fascia for not less than 0.5 seconds. With the engine running, all doors closed and the vehicle speed below 18 mph (30 km/h), the audible warning will sound once and the ORM warning lamp in the instrument pack will start to flash when the switch is released. The compressor will be started and the air control valves will be energised by the ECU to inflate the air springs and raise the rear of the vehicle.

When the full ORM height is reached, the ECU will terminate compressor operation and close the air valves. The ORM warning lamp will stop flashing and remain continuously illuminated to inform the driver that the SLS system is in ORM.

When ORM is no longer required, depressing the ORM switch for not less than 0.5 seconds with all doors closed will lower the SLS to normal ride height. The audible warning will sound once and the ORM warning lamp will flash as the suspension lowers. The ECU energises the air control valves and the exhaust valve to release air pressure from the air springs. When standard ride height is reached the ORM warning lamp will extinguish and the ECU will de-energise the air control valves and the exhaust valve solenoids.

If the SLS is in ORM and the vehicle speed exceeds 18 mph (30 km/h), the ECU will lower the SLS to standard ride height. The driver will be informed of this by an audible warning and the ORM warning lamp flashing as the suspension lowers. When normal ride height is achieved, the ORM warning lamp will extinguish.

At sea level, the time to change the SLS from normal ride height to ORM or visa versa will take between 15 and 20 seconds.

If the ECU determines that conditions are not correct for SLS operation, i.e.; axle articulation or system fault, the audible warning will sound three times to inform the driver that the ORM request has not been granted.

Extended mode The extended mode is automatically operated by the ECU and requires no input from the driver. Extended mode operates when the chassis is grounded causing the rear wheels to spin. This information is generated by the ABS function of the SLABS ECU.

When the ECU senses that the chassis is grounded and the vehicle speed is less than 6 mph (10 km/h), the ECU will operate the compressor and energise the air control valves for 25 seconds to raise the rear of the vehicle. This operates irrespective of the mode that the SLS system is in at that time. To inform the driver, the ORM warning lamp will flash continuously at all times that the system is in extended mode.

The driver can exit the extended mode by depressing the ORM switch for not less than 0.5 seconds or by exceeding 8 mph (13 km/h).

Remote handset SLS control The remote handset is an accessory item which allows the SLS to be operated between normal ride height and bump stop height to allow easier connection and disconnection of trailers. The remote handset is similar in appearance to that of the remote door locking handset but does not have an integral key. A circular button with an arrow is used to raise the SLS and an oval button with the 'Land Rover' logo is used to lower the SLS.

The remote handset control requires all doors to be closed and the ignition to be in position II, but the engine does not need to be running.