relay BMW X5 2000 E53 Workshop Manual

14
System Operation
The seat backs are adjusted from the two different locations as follows:
• The switches in the interior light housing receive operating power through the seat back
relay when the ignition is switched on KL 15. The GM controls the operation of the relay
and the switches provide the ground.
• The switches in the “D” pillar receive KL 30 and allow seat back adjustment whenever
the rear tailgate is opened to gain access to the switches.
• The adjustment motors receive power and ground directly from the switches.
MM
General ModuleBackrest RelayBackrest Adjustment
Switch LeftBackrest Adjustment
Switch Right
Backrest Adjustment
Switch LeftBackrest Adjustment
Switch Right KL30
Motor, Backrest Left Motor Backrest Right

19
45
80 72
TE MP
M
+
+
+
½
P
1
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5
6
7!ABS
    
  









 
mi le s0
10 15 20 40+
DME
M
KL31
KL30
KL15
Fan Speed
Request
A/C Compressor
Recirculation
Rear Defrost
Temperature
Control
Evaporator
Temperature SensorWasher Jet Heater
Blower Relay
Blower
Blower Motor Ouput Stage
M
Rear Window Defoger Relay
Aux. Fan Speed Relay Control
Water Valve
Fresh Air Flap Motor
IKE
DME
Compressor Control
Aux. Fan
IHKR
K-Bus
Refrigerant Pressure Sensor
C
A
N
DIS & Modic
IHKR IPO
64530006.cdr

Air Supply System (LVA)
The air supply system is identified as the LVA in the diagnosis program and in the repair
manual. It is mounted in the spare tire well compartment. The components are housed in
a sound deadening carrier, through rubber bushings, to prevent operating noises from
being transmitted through the vehicle’s interior.
With the exception of the compressor relay, individual replacement parts for the air supply
system are not available. If diagnosis determines a defect in any of the other air system
components, complete replacement is necessary.
The air supply system consists of the following components:
• Compressor assembly with;
- Piston compressor
- Electric motor
- Air dryer (desiccator)
- Pressure relief solenoid valve
- Pressure maintenance valve
- Check valves
• Compressor Relay (Replaceable)
• Solenoid Valve Block (2 - two way valves)
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3753000237530001

Air Supply System (LVA) Operation
The single stage piston compressor produces a maximum pressure of 13.5 Bar. The com-
pressor is maintenance free - provided it is used in a dust free environment. This includes
the compressor’s intake air filter.
The compressor is driven by a DC motor that is controlled by the compressor relay through
the control module.
When the compressor is activated, the pressure builds up to a working pressure of 11.4
Bar (+0.8/-1.5 Bar). This is controlled through the pressure maintenance valve. The air
under pressure is fed through the dryer and check valve to the solenoid valve block for the
air springs.
There is one solenoid valve in the valve block for each air strut. This allows the system to
compensate for uneven loads in the vehicle and maintain the vehicles ride height at all
times.
Pressure is drained through the left or right solenoid valve (energized open) the pressure
relief solenoid valve, restricter, check valve and dryer back to the inlet side of the compres-
sor pump.
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