Lamborghini Diablos (after 1993), the Murciélago and from 2005
onwards Gallardo's have a system that allows the driver to raise the
front of the car about 2 inches (when driving at low speeds) to get
over obstructions on the road or driveway. Unfortunately this system
is a notoriously badly designed system. It is perhaps the greatest
failure in the design of Lamborghini cars and is the subject of
numerous discussions in Web forum discussion groups. A major
problem with this system is that the front Koni shocks (through
which oil is pumped into to rise the car) leak. There are
particularly prone to do so if they are "bumped" when the car is in
the raised condition. The oil pressure system puts out over 1500 PSI
to raise the car. The seals in the shocks simply are not designed
take this pressure.
To make matters worse Koni insists that these shocks are an OEM job
and will or cannot repair or replace them. The only current solution
is to purchase expensive new shocks from Lamborghini.
A number of people have tried to find a solution. The problem is
that the shocks themselves are almost impossible to open. The treads
are sealed with some kind of "locktight" cement. Some people I know
are working on a solution. Nothing yet!
- There is a second problem sometimes seen with the above front
lifting system. The symptoms are as follows: When the driver pushes
the switch to raise the car, the car rises fine to its maximum
and then immediately drops down again leaving the "raised car"
flashing on the dash. Further pressing the switch has no effect
unless the car engine is turned off and then back on. In this
situation there are no shock oil leaks, the power steering oil
reservoir (see below) is full and the Koni error lamp beside the gear
shift is not flashing an error code. The cause of this problem
is tricky to diagnose. To do this it is first necessary to
understand how the front lifting system in these cars work.
The Koni Front Lifting System in a
- The front lifting system in Diablos (and the more recent cars) is
done by pumping power steering oil under very high pressure into two
specialized Koni shock absorbers in the front of the car. The
circuit diagram is shown in the following two diagrams.
|Fig 2 Diagram of oil
reservoir and Min/Max Switches
||Fig 3 Diagram of front air bleed
As can be seen in the above diagrams the oil for the front rising
system is pumped from the power steering reservoir through a valve
system to both front shocks. Even tough the same oil reservoir is used
by both the front lifting system and the power steering system they behave
quite separately. The same pump is used to pressure the oil in both systems
The onboard LIE computer carefully
monitors the oil pressure put out by the pump required to raise the car. This
goes from less than 20 Bar (~260 PSI) to over 100 Bar (~1500 PSI) as
the car is raised. You need this kind of pressure to raise
such a heavy car with such small hydraulic pistons (in the shocks).
To monitor the pressure there are two pressure sensors, a MIN
pressure and MAX pressure sensor switch. These are shown in Figure
4. They are clearly labeled in the steel block they are screwed
into. This assembly is located just above the gas tank in the side
compartment of the engine area. The Min switch has a adjustable
screw painted red. The Max switch screw is painted blue. These screws
should normally not be tampered with. They are factory set to set
the cutoff pressures for the front hydraulic lifting system and are very sensitive. A slight
adjustment of 5 degrees has a big effect see below.
The way the system works is as follows: The Min switch is a
"normally open" switch so when the car is in its (normal) low
position, this switch is set open. Removing the two wire connections and measuring
the resistance across the switch should show an open connection when the car is in its
normal low position. The Max switch on the other hand is a "normally closed" switch. When the car is in the
normal (lowered) position removing the two wire connections should
show essentially no resistance across the switch contacts. When the car
is raised. The min switch should close (as the pressure passes
above 40 Bar) and remain closed. When the car is full up (and the pressure
is over 80 Bar) the Max switch will open. Both switches should
remain in these states while the car is raised. They reverse back to
their original states when the car is lowered.
Both switches have a grey/red wire connector that is connected to
ground for both switches. You can check the switches are opening and
closing correctly by measuring the voltage of the violet/white lead on the Min switch and the
green/black lead of the Max switch during the raising and
lowering process. To see the voltage changes
attach a voltmeter clip to the switch contact (at the same time
making sure the wire contact supplying the voltage to the switch is
not disconnected) and tape the meter to the car window as shown in
figures 5 and 6. Then raise the front of the car. For the Min switch
the voltage should be +12V quickly going to 0V and staying
there as the car is rising. For the Max switch on the other
hand the voltage will be 0V going to +12 volts and
staying there once the car is full up.
- There are two common ways this front lifting system can
Oil Pressure Failure: If
the power steering pressure pump is not capable of delivering the 1500+
PSI pressure the car can not be raise correctly. To check this you
will need to monitor the oil pressure being sent to the front shocks system.
Fortunately Lamborghini provides a location to tap into the system. It is
behind the panel in the front trunk as shown in figures 7 and 8. This is
actually an air bleed screw to get air out of the system during an oil
change. To measure the oil pressure we will construct a custom oil
First let me warn you that we are talking about very high oil
pressures here. A pipe burst at 1500 PSI will spray oil everywhere and
potentially cause bodily injury. Even when the car is lowered the
oil pressure in the system is still ~260 PSI.
- You need to purchase a pressure gage capable of measuring up to ~1500
PSI. This is well beyond gages commonly used for automatic
transmission or diesel engine work. You can get such a gage from
for about $25.00.
- Its part number is #53783 and is made by a company called Valley Instrument.
To attach this gage to the car system you must first relieve the
pressure in the system by attaching a hose and container to the air
bleed and opening it slowly. See figure 9. When the oil stops flowing
remove the air bleed vent. This leaves you with a female fitting.
Fortunately this is exactly the same 0.4" treads that are used in brass
tubing fittings found in most (US) hardware stores. You need to setup an
assembly as shown in figures 10 and attached it to the car as shown in
figure 11. You have to attach the vertical stem first, then attach the
stopcock and gage. All joints should be Teflon taped and quite
tight. This process can be quite messy. It's a good idea to cover the
whole area with plastic covering and wrap a rag around the base of the
air bleed area to absorb runoff oil. With
the assembly in place (and the stopcock open) start the engine and raise
the car. Quickly check for leaks! With the car full up, the oil pressure
should go to about 1400 PSI and then fall back to ~1200 PSI (fig 12). When the
car is lowered the pressure drops and stays at about 250 PSI (fig 13). If
you do not see these numbers you may need to replace the power steering
Now to put things back you need to relive the oil pressure in the
system. Close the stopcock and carefully remove just the pressure gage
Then put a container under the stopcock and open it. When the oil stops
flowing remove the vertical brass tube and put back the Lamborghini air
bleed. Tighten it down. You will also have to add some power
steering oil to the reservoir in the back of the car. If the oil
did not come within the above pressure values you either have a failing
power steering pump or faulty sensor switches (see below).
As a side note, perhaps the reason these KONI shocks tend to leak is
that they always have 250 PSI pressure in them even when the car is in
the lowered position. It's not clear to me why this is so. If you vent
off the pressure (as described above) the pressure will stay at 0 PSI
until the next time the car is raised -- even when the power steering is
used. Perhaps the Min oil pressure sensor switch could be adjusted
downwards. Some day maybe I will experiment!
- Failure of Min Oil Pressure
For some reason it is quite common for the Min switch to fail. When
it fails the switch contacts
open always. This will cause the car to rise and then quickly fall
back down. It is easy to check for this by bypassing the
shown in Figure 15. The car should then raise correctly and stay up. (The
icon on the dash indication the car is raised will stay flashing --
indicating an error however). Nevertheless you can raise and lower
the car with no problem. Note the Max switch could fail too.
Check the voltage readings as described above to be sure.
To replace the Min switch you must release the oil pressure with the
oil/air bleed system as
described above. You them need to drain the power steering fluid
I find the easiest way to do this is to siphon it out using a brake
fluid vacuum pump to get things started. To be on the safe side you should
surround the Min/Max switch block area with some rags (fig 16). You don't want oil
dripping on top of the gas tank area below. Now we are ready to
remove the Min switch. Remove the connecting wires and with a 25mm
socket carefully screw out the assembly see fig 17 & 18 (Note in fig 17 rags were
removed for photograph). Be real
careful not to loose the brass/rubber gasket (fig19). Transfer
this gasket to the new unit and screw the new unit back in. The
Lamborghini part number for this switch is #51009370 (It costs
~$245*). Reconnect the wires. Fill the power steering
oil reservoir to within 1 inch of the top. Do not overfill this
reservoir. If you do it will overflow through a small bleed hole
(figures 20 & 21) in the rubber top knob and drip down on to
the compartment below.
You are now ready to test the lifting system. The first time you
start the system up, it seem to take a little longer to raise the car.
This is because the pump is building the pressure up from 0 PSI to the
normal base 250 PSI. The car starts to rise from then on. This can be
easily seen if you use the oil pressure gage setup I described above.
It may be necessary to bleed air out of the system -- though I have not
found this to be so -- using the oil/air bleed nozzle I described above.
* The Lamborghini "Pressure Regulator - Min" costs $250.00.
Interestingly what looks like the exact same switch sold by PLV Ltd in
England costs 25 Euros. See
http://www.pvl.co.uk/datafaxes/1021 - PMN.pdf. Lamborghini parts