Description of Components
DESCRIPTION OF COMPONENTS Electrical
Control Unit - ECU
The ECU is located underneath the front left hand seat. The ECU maintains the requested vehicle ride height by adjusting the volume in each air spring. It is connected to the cable assembly by a 35 way connector. To ensure safe operation the ECU has extensive on board diagnostic and safety features. The ECU must be replaced in case of failure.
Air Compressor
NOTE: The air compressor and valve block are contained in the under bonnet unit mounted on the left hand inner wing.
The air compressor provides system pressure. A thermal switch is incorporated which cuts out compressor operation at 120°C. An air filter is fitted to the compressor head. The filter is renewed every 40,000 km (24,000 miles), or every 30,000 miles in NAS markets
Air Dryer
The air dryer is connected into the air line between the compressor and reservoir. It is mounted on the engine air cleaner box. The dryer removes moisture from pressurized air entering the system. All air exhausted from the system passes through the dryer in the opposite direction. The air dryer is regenerative in that exhaust air absorbs moisture in the dryer and expels it to atmosphere.
The air dryer is non-serviceable, designed to last the life of the vehicle. However, if any water is found in the system, the air dryer must be replaced.
CAUTION: If the air dryer is removed from the vehicle the ports must be plugged to prevent moisture ingress.
Valve Block
The valve block controls the direction of air flow. Air flow to and from the air springs is controlled by seven solenoid operated valves, one for each spring plus an inlet, exhaust and outlet. In response to signals from the ECU, the valves allow high pressure air to flow in or out of the air springs according to the need to increase or decrease pressure. A diaphragm valve operated by the solenoid outlet valve ensures that all exhausted air passes through the air dryer.
Mounted on the valve block is a pressure switch which senses air pressure and signals the ECU to operate the compressor when required.The compressor will operate when the pressure falls between 7.2 and 8.0 bar (104 and 116 psi). It will cut out at a rising pressure of between 9.5 and 10.5 bar (138 and 152 psi).
The valve block contains the following serviceable components: Solenoid coils 1 to 6, drive pack and pressure switch.
The valve block must only be dismantled after the correct diagnosis procedure.
Reservoir
The 10 litre reservoir is mounted on the right hand side of the chassis. One connection acts as air inlet and outlet for the rest of the system. The reservoir stores compressed air between set pressure levels. The reservoir drain plug requires removing to check for moisture in the system every 40,000 kms. (24,000 miles), or every 30,000 miles in NAS markets.
Height Sensors
Four potentiometer type height sensors signal vehicle height information to the ECU. The potentiometers are mounted on the chassis and activated by links to the front radius arms and rear trailing links. A height sensor must be replaced in case of failure, and the vehicle recalibrated using Testbook.
Air Springs - Front And Rear
The air springs consist of the following components:
1. Top plate
2. Rolling rubber diaphragm
3. Piston
Front and rear air springs are of similar construction but are NOT interchangeable. The diaphragm is not repairable, if failure occurs the complete air spring must be replaced
Driver Controls
Mounted in the centre of the dashboard, the driver controls consist of an UP/DOWN switch, an INHIBIT switch and a height setting indicator.
Relays, Fuses
Located in the under bonnet fuse/relay box are 2 relays, plus 10, 20 and 30 amp fuses.