LR3/Disco 3
corrections. The system will remain inhibited until the rapid deceleration rises above -0.15g. Deceleration is calculated by
the air suspension control module from a vehicle speed signal received via the high speed CAN bus.
Vehicle Jack
The air suspension control module will inhibit all height changes and corrections if it detects a corner lowering too slowly
for more than 1.2 seconds. This is interpreted as the corner identified as moving too slowly being supported on a jack. In
this situation, the corner height will not change when air is released from the air spring because the jack acts as a
mechanical prop. The system will remain inhibited until any of the following conditions exist:
l
The air suspension switch is moved to the up or down position
l
Vehicle speed rises to more than 9.3 mph (15 km/h) for more than 15 seconds.
Door Open
The air suspension control module will stop all height change requests while any of the doors are open. Vehicle levelling
continues with a door open by keeping the vehicle at the height when the door was opened if the vehicle load changes.
Diagnostics
The air suspension control module can store fault codes which can be retrieved using T4. The diagnostic information is
obtained via the diagnostic socket which is located in the lower instrument panel closing panel, on the driver's side, below
the steering column.
The diagnostic socket allows the exchange of information between the various control modules on the bus systems and
T4 or a diagnostic tool. This allows the fast retrieval of diagnostic information and programming of certain functions using
T4.
Fault Detection
The air suspension control module performs fault detection and plausibility checks. Fault detection is limited to faults that
the control module can directly measure as follows:
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Sensor electrical hardware faults
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Valve electrical hardware faults
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Sensor and actuator supply faults
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Bus failures
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Control module hardware errors.
Plausibility checks are checks on signal behaviour, as follows:
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Average height does not change correctly
¡
Height changes too slowly
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Gallery pressure
¡
Does not increase fast enough when reservoir filling requested
¡
Increases when system is inactive
¡
Too low when lifting is requested
¡
Increases too rapidly when filling reservoir
¡
Does not decrease when gallery is vented
¡
Pressure varies too much when inactive.
l
Compressor temperature
¡
Sensor voltage too large - head and brush sensors (short circuit to battery)
¡
Takes too long to be readable after suitable compressor run time - head and brush sensors
¡
Does not increase when compressor active - head sensor only
l
Sensor activity
¡
Signal floating
¡
Constant articulation when moving
When a fault is detected, the air suspension control module will attempt to maintain a comfortable ride quality and where
possible will retain as much functionality as possible.
The system functionality depends on the severity of the fault.
Faults
