Range Rover Classic. Manual — part 117
68
AIR SUSPENSION
8
DESCRIPTION AND OPERATION
Delayed turn off relay - remains energised after
switching engine off and exiting vehicle, enables self
levelling to occur for 20 seconds. If vehicle is
stationary, the ECU will energise the relay every six
hours to allow self levelling to occur if necessary.
Reservoir pressure switch - when the ECU detects
an output from the pressure switch indicating low
pressure, the ECU will operate the compressor relay
until the pressure switch indicates normal pressure.
Diagnostic plug ground - note that the two halves of
the diagnostic plug are normally connected. When
disconnected the system will not operate. It will
remain frozen at its current height until reconnected.
Disable switch - In the disable position the switch
sends a door open signal to the ECU. This freezes the
system in position at speeds below 56 kph (35 mph).
AIR SUSPENSION
9
DESCRIPTION AND OPERATION
SYSTEM FUNCTION
The following table indicates conditions required for various air suspension modes.
NOTE: That the engine must be running unless indicated, and that ACCESS may be selected for 15
seconds after switching engine off.
Function
Condition
Warning
lamp
on
1.
Automatic functions - Inhibit switch OFF.
High profile to standard
Over 56kph (35mph)
No
Standard to low profile
Over 80kph (50 mph) for 30 secs
Lower
Low profile to standard
Below 56kph (35 mph) for 30 secs
No
(but above 1.6 kph (1 mph))
Access to standard
Park brake off or drive away
No
2.
Driver select functions - Inhibit switch OFF.
Standard to high profile
Raise switch below 56kph (35 mph)
Raise
High profile to standard
Lower switch below 56kph (35 mph)
No
Standard to access
Lower switch
)Stationary/
Lower
)park brake on
Low profile to access
Lower switch
)- manual/
Lower
(where vehicle has not returned to standard
)transmission P
)- automatic/
High to Access
Press lower switch twice
)doors shut
Lower
Access to standard
Raise switch
Lower
Access to high
Press raise switch twice
Raise
3.
Inhibit switch ON
High profile to standard
Below 56kph (35 mph)
Inhibit
Low profile to standard
Inhibit
Access to standard
Stationary/park brake on
Inhibit
4.
Self levelling
Vehicle levelling for 20
Stationary/engine off/
No
secs, and every 6 hrs
exit vehicle
AIR SUSPENSION
1
FAULT DIAGNOSIS
DIAGNOSTICS AND FAULT RECOVERY
The ECU incorporates Fault Recovery Strategies to
minimise the effect of a system failure. A serial data
link is provided to allow diagnostic information to be
retrieved using TestBook. This is also used to set
height sensor datum when required.
Note that the serial link connector is coloured black for
identification purposes. Any faults stored in the ECU
memory, from the previous or current running period
will cause the ECU to flash the RAISE and LOWER
lamps for 30 secs. followed by continuous illumination.
If the ECU registers a system fault, it will store the
fault in the memory. The fault recovery programme
will operate the system depending on the nature of the
fault as follows:
Speed sensor fault - the ECU will place the system
in standard height and activate inhibit.
Height sensor fault - the ECU will place the system
in standard height and activate inhibit. Note that if
more than one height sensor fails, the ECU will deflate
the air springs to the bump stops.
WARNING: If any two failure occur the
system deflates and lowers vehicle to its
bump stops, it is possible to drive the
vehicle provided that great caution is exercised.
The vehicle ride will be extremely uncomfortable
and only low speeds will be possible. It is
essential that the vehicle fault is rectified as soon
as possible.
Pressure switch fault - the ECU will register
pressure switch failure if it detects that the
compressor has worked for a programmed time with
normal air spring operation possible. The ECU will
periodically operate the compressor as air is required.
The vehicle will be inhibited to standard.
Compressor fault - the ECU will register compressor
failure if it detects that the compressor has worked for
a programmed time with normal air spring operation
not possible. The ECU will attempt to place the
system in standard ride height, or a safe lowered
position (which could be system deflated). The system
will be inhibited from further ride height changes.
Air leaks - during normal operation the ECU
correlates the operating time of the compressor with
air usage. If compressor use is greater than
programmed, the ECU will register an air leak and
attempt to place the system in standard ride height, or
a safe lowered position (which could be system
deflated). The system will be inhibited from further ride
height changes.
Valve block fault - the control of each air spring is
monitored to determine that every valve is working
correctly.
1. If the ECU detects an air valve stuck open it will
attempt to adjust the vehicle to standard height
or a safe lowered position (which could be
system deflated). The system will be inhibited
from further ride height changes.
2. If an air valve is stuck closed above standard
height the ECU will deflate the other three air
springs.
3. If an air valve is stuck closed, at or below
standard height, the ECU will attempt to adjust
the other springs to the same height and activate
inhibit.
AIR SUSPENSION CIRCUIT DIAGRAM
See Electrical Trouble Shooting Manual.
AIR SUSPENSION
1
ADJUSTMENT
DEPRESSURISE SYSTEM
Service repair no - 60.50.38
Service tool:
TestBook
Depressurise
WARNING: Air suspension is pressurised
up to 10 bar. Dirt or grease must not enter
the system. Wear hand, ear and eye safety
standard protection when servicing system.
1. Connect TestBook and follow instructions to
depressurise complete system.
CAUTION: Depressurising system will
lower body on to bump stops.
2. Ensure system is completely depressurised:
Check that all air springs are deflated, and
vehicle has dropped evenly on to the bump
stops. If a spring, or springs, remains inflated
possibly due to a stuck solenoid valve, it will be
necessary to disconnect the pressurised pipe at
that air spring.
WARNING: Wear hand, ear and eye safety
standard protection. For extra protection
wrap a clean cloth around pipe to be
disconnected. Note that vehicle will lower to bump
stop when pipe is disconnected.
3. Disconnect air pipe.
See Repair,
Disconnect/Connect Air Pipe
4. Disable system using switch under rear of RH
front seat.
Repressurise
1. Switch disable switch OFF.
2. Run engine to repressurise system.
SYSTEM CALIBRATION - HEIGHT SENSOR
DATUM
Equipment required:
TestBook
NOTE: This procedure must be carried out
when a new ECU or height sensor has
been fitted.
Calibration will also be required if any part affecting
damper relationship to body is changed i.e. damper
mounts, axles, chassis unit and body panels. The
vehicle can be calibrated laden or unladen, but Gross
Vehicle Weight must not be exceeded. Tyres must all
be the same size and at the correct pressures.
IMPORTANT: The floor used for calibration must
be level and smooth in all directions to enable
procedure to be carried out successfully.
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