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Page 8 of 18

TECHNICAL SERVICE OPERATIONS

7.1 Did you hear a hissing/venting noise?

TECHNICAL SERVICE OPERATIONS

Note: Save a psdata file and a PDF file of the measurements carried out with PicoScope for each
execution of the active diagnosis to obtain a total of four files relating to this point 8.
If fuse F41 blows while carrying out this test, replace it
Did fuse F41 blow while performing this test?
YES

9.

NO

Return the Vehicle to ‘Normal’ height level.

Carry out, twice as described below, the active diagnosis ASCM > Active diagnosis > Actuator Test,
selecting (one at a time):
- FL (Front Left).
- FR (Front Right).
- RL (Rear Left).
- RR (Rear Right).
Between the first and second runs, bring the car back to ‘Normal’ height level.
Before and after the first execution of the two necessary ones, record, in Table 2 of Annex C: summary
table of vehicle corner height measurements, the height of all the corners of the car.
The diagnostic tool screen is shown in Figure 6 for reference.
Using this diagnosis, the reversal valves inside the compressor and the valve of each air spring are
activated to deflate each individual air spring, one by one.
The expected result on a properly functioning car is:
- All springs deflate (reaching the same height).
- The springs deflate one at a time: this means that you must not deflate more than one at a time.
First execution of the active diagnosis:
a. Channel A: current absorbed by the compressor (B1: current absorbed by the compressor), and, at
the same time
b. Channel B: current absorbed by the valve block (B2: current absorbed by the valve block).
Second run of active diagnosis:
a. Channel A: current absorbed by the compressor (B1: current absorbed by the compressor), and, at
the same time
b. Channel B: current absorbed by the valve block (B3: current absorbed by the reversing valves).

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Page 9 of 18

TECHNICAL SERVICE OPERATIONS
Figure 6: Active Diagnosis > Actuator Test.

Note: Save a psdata file and a PDF file of the measurements carried out with PicoScope for each
execution of the active diagnosis to obtain a total of four files relating to this point 9.
If fuse F41 blows while carrying out this test, replace it.
Did fuse F41 blow while performing this test?
YES

NO

Annex B: Compressor current absorption test, valve block and compressor reversing valves
Note: Before starting the current measurement with a clamp meter, it is necessary to reset the current
reading, i.e. make sure that, in the absence of currents, the value read on PicoScope is equal to zero. To
reset the clamp meter, use the zeroing knob on the clamp
B1: Current absorbed by the compressor
The measurement of the current absorbed by the air suspension system compressor can be easily done by
accessing the X090 connector located near the rear differential.
The location of the X090 connector, in the car, is shown in Figure 7.

Figure 7: position of the X090 connector for the current measurement absorbed by the compressor during the actuations.

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TECHNICAL SERVICE OPERATIONS

To access it, we recommend releasing the blue connector shown in Figure 8.

Figure 8: secondary lock (blue, indicated by the arrow) of the X090 connector..

The air suspension system compressor power cable is the red cable shown in Figure 9.

Figure 9: power supply wiring to the air suspension compressor.

Figure 10: current clamps to be used for the measurement of current absorbed by the compressor

To measure the current absorbed by the compressor, it is necessary to follow these steps:
1. You can use the TA167 current clamp (with a capacity of 2000 A to be set in 200 A configuration, using
the selector on the clamp itself), or the TA019 clamp (with a capacity of 600 A).
2. Connect the current clamp to connector A on the PicoScope instrument.
3. Choose correct parameter on the PicoScope software. Click on channel A and choose:
to. 2000 A clamp in 200A configuration if the TA167 clamp meter is used, or
b. 600 A clamp if using the TA019 clamp.
The settings are shown in Figure 11
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MAS004274

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Page 11 of 18

TECHNICAL SERVICE OPERATIONS
Figure 11: settings of PicoScope for the choice of the current clamp.

1.

Set the correct scale from the “scale setting” drop-down menu next to channel A: -100A/200A.

2.

Set 2 s/div and sample rate to 100 kS. In this way it is possible to have a sampling frequency equal to 5 kHz: the
sampling refers to the number of samples stored in the total window of 10 divisions that is displayed on the
screen: with 2 s/div I will have 10 divisions and therefore on the screen I will see a measurement of 20 s. By
doing so, therefore, the frequency will be equal to
𝑓=

Samples
100 𝑘𝑆 100000
=
=
= 5000 Hz
Sample Time
20 𝑠
20 𝑠

PicoScope connections and settings
Channel A scope

Current clamp TA019 (capacity 600 A) or current clamp TA167 set to 200
A
-100 A/200 A DC
2 s/div
100 100 kS (100.000 samples)

Channel A scale setting
Time scale settings
Sampling

3.

Save measurements in psdata and PDF format.
Figure 12 shows the typical current absorption profile of the compressor during leveling.

Figure 12: typical compressor current absorption profile during levelling.

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Page 12 of 18

The measurement of current absorbed by the valve block of the air suspension system can be made from pin 23
of connector B of the ASCM module, as shown in Figure 13.
Since, in this case, the current values are lower than those of section B1: current absorbed by the compressor, in
addition to the fact that these measurements must be made at the same time as the measurement of current
absorbed by the compressor, it is required in this to connect the TA018 current clamp, which has a capacity of
60A.
This clamp is shown in Figure 14.

TECHNICAL SERVICE OPERATIONS

B2: current absorbed by the valve block

Figure 13: outline of the wiring diagram of the valve block

Figure 14: TA018 current clamp.

Since the X090 connector shown in B1: compressor current draw is easily accessible than the ASCM connector B,
measure the current by accessing pin 16 of the yellow-green harness of the X090 connector, as shown in Figure 15.

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Page 13 of 18

TECHNICAL SERVICE OPERATIONS
Figure 15: pin 16 of connector X090 (yellow-green wiring).

To measure the current absorbed by the valve block, it is necessary to follow these steps:
1. Use the TA018 current clamp (with a capacity of 60 A to be set in 20 A configuration, using the selector on the
clamp itself).
2. Connect the current clamp to connector B on the PicoScope instrument.
3. Choose correct parameter on the PicoScope software. Click on channel B and choose the 60 A Current Clamp
(20 A mode).
The settings are shown in Figure 16.

Figure 16: settings of the 60 A current clamp..

4. Set the correct scale from the “scale setting” drop-down menu next to channel A: -/+5A.
5. Set 2 s/div and sample rate to 100 kS.
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Page 14 of 18

Channel B scope
-5 A/5 A DC
2 s/div
100 kS (100.000 samples)
TA018 Current Clamp (capacity 60 A) with selector on 20 A

6. Save the measures in psdata and PDF formats.
Figure 17 is the typical current absorption profile by the valve block when performing an Actuator Test is shown.

TECHNICAL SERVICE OPERATIONS

Channel B scale setting
Time scale settings
Sampling
Channel B scope

Figure 17: typical valve block current absorption profile during the execution of an Actuator Test.

B3: current absorbed by the reversing valves
The measurement of the current absorbed by the reversing valves of the air suspension compressor can be done
from pin 46 of connector B of the ASCM module, as shown in Figure 18.
In this case as well, as in the case B2: current absorbed by the valve block, the values of current are lower than
those measured in the section B1: current absorbed by the compressor, in addition to the fact that these
measurements must be made at the same time as the measure of the current absorbed by the compressor, it is
required in this to use the current clamp TA018, which has a capacity of 60 A. This clamp is shown in Figure 14.

Figure 18: outline wiring diagram of the air suspension compressor.

As the connector X090 shown in B1: current absorbed by the compressor is more accessible than the connector B
Page 15 of 18
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MAS004274

TECHNICAL SERVICE OPERATIONS

of the ASCM, measure the current by accessing the grey-green wiring pin 8 of connector X090,shown in Figure 19.

Figure 19: pin 8 of connector X090 (grey-green wiring).

The TA018 current clamp can be located close to the TA0167 or TA019 current clamp, the latter being used to
measure the current absorbed by the air suspension compressor.
In order to perform the measurement of current absorbed by the valve block, follow these steps:
1. Use the TA018 current clamp (with a capacity of 60 A to be set in configuration 20 A, by selector on the clamp
itself).
2. Connect the current clamp to connector B of the PicoScope tool.
3. Choose correct claps on PicoScope software. Click on channel B and choose the clamp 60 A Current Clamp
(20 A mode).
The settings are shown in Figure 16.
4. Set the correct scale from the "scale setting" drop-down menu next to channel A : -/+5A.
5. Set 2 s/div and sampling frequency to 100 kS.

Channel B scope
Channel B scale setting
Time scale settings
Sampling

6.

PicoScope connections and settings
TA018 Current Clamp (capacity 60 A) with selector on 20 A
-5 A/5 A DC
2 s/div
100 kS (100.000 samples)

Save the measurements in psdata and PDF formats.

In Figure 20 a typical profile of the current absorption by the reversing valves group when performing an Actuator
Test is shown.

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MAS004274

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Page 16 of 18

TECHNICAL SERVICE OPERATIONS
Figure 20: typical current absorption profile of the compressor reversing valve assembly when performing an Actuator Test..

The expected values (normal values) are summarized below for compressor, valve block and reversing valves:
a. Compressor:
Average maximum current ≤ 36 A
Initial peak current ≤ 120 A during a time interval ≤ 200 ms.
b. Valve block power supply:
Maximum peak current ≤ 0,75 A
Maximum constant current ≤ 0,5 A
c. Reversing valves inside the compressor:
Maximum peak current ≤ 2 A
Maximum constant current ≤ 1,2 A
Attachment C: summary table of the Vehicle Heights of each Vehicle corner
Table 1: table to register the Vehicle Heights for steps 5, 6, and 7..
Step 5
(mm)

After Step 5.2*
(mm)

After Step 5*
(mm)

After Step 6
(mm)

After Step 7
(mm)

Front Left
Front
Right
Rear Left
Rear
Right

* if needed.

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Before Vehicle
Articulation
Routine
(mm)

After Vehicle
Articulation
Routine (mm)

Before
Actuator
Test
(mm)

After
Actuator Test
(mm)

Front
Left
Front
Right
Rear
Left

TECHNICAL SERVICE OPERATIONS

Table 2: table to register the Vehicle Heights at steps 8 and 9.

Rear
Right

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MAS004274

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Page 18 of 18