This diagnosis activates the reversing valves inside the compressor and the valve of each air spring, subsequently
inflating each air spring one by one.
The expected result on a properly functioning vehicle, is that:
All springs are inflated and deflated (reaching the same height).
The springs are inflated and deflated one at a time: this means that no more than one at a time must be
involved.
Simultaneously, for the purpose of evaluating the performance of the ASCM ECU, it is necessary to measure the
current absorbed by the compressor, valve block, and reversing valves inside the compressor during active
diagnosis executions.
Please refer to Attachment B: Current Absorption of the Compressor, Valve Blocks, and Compressor Reversing
Valves Test for detailed instructions on how to measure the electrical current absorbed by these system
components.
Due to this requirement, Step 9 needs to be repeated twice. It is necessary to measure the current simultaneously
by connecting to channel A and channel B of the PicoScope instrument, respectively.
First execution of the Active Diagnosis
a. Channel A: current absorbed by the compressor (Note: Before initiating the current measurement with
current clamps, it is necessary to reset the current measure and ensure that the current reading on the
PicoScope is zero in the absence of any current. To reset the current clamp, use the knob located on the
clamp itself.
b. B1: and at the same time
c. Channel B: current absorbed by the valve block (B2: current absorbed by the valve block).
Second execution of the Active Diagnosis:
a. Channel A: current absorbed by the compressor (Note: Before initiating the current measurement with
current clamps, it is necessary to reset the current measure and ensure that the current reading on the
PicoScope is zero in the absence of any current. To reset the current clamp, use the knob located on the
clamp itself.
b. B1: and at the same time
c. Channel B: current absorbed by the reversing valves inside the compressor (B3: current absorbed by
the reversing valves).

Figure 6: Active Diagnosis > Actuator Test.

Note: it is possible to save one psdata and one PDF file of the measures with PicoScope for each one of the two
executions of the Active Diagnosis so that an overall four files are created for this step 9. If the F41 fuse blew
during this test, replace it.
Did the F41 fuse blow?

☐YES
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NO☐
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Attachment B: Electrical current absorption of the compressor,
valve blocks and compressor reversing valves test
Note: Before initiating the current measurement with current clamps, it is necessary to reset the current measure
and ensure that the current reading on the PicoScope is zero in the absence of any current. To reset the current
clamp, use the knob located on the clamp itself.
B1: Electrical current absorbed by the compressor.
The measurement of the current absorbed by the air compressor can be easily done by accessing the red wiring
at the X090 connector, which is located near the rear differential. The position of the X090 connector, in the
vehicle, is shown in Figure 7. To access it, it is recommended to release the blue lever shown.

Figure 7: position of the X090 connector for the current measurement absorbed by the compressor during the actuations. And secondary
lock (blue, indicated by the arrow) of the X090 connector

The air suspension system compressor power wiring is the red one shown in Figure 8.

Figure 8: power supply wiring to the air suspension compressor.

Figure 9: current clamps to be used for the measurement of current absorbed by the compressor.

To perform the current measures, one should follow the following steps:
1. The current clamp TA167 (with a capacity of 2000 A to be set in configuration 200 A, by selector on the
clamp itself) or the TA019 clamp (with a capacity of 600 A) can be used.
2. Connect the current clamp to connector A of the PicoScope tool.
3. Choose the correct clamp on PicoScope software. Click on Channel A and choose:
a.
Clamp with 2000 A capacity in 200A configuration if the TA167 current clamp is used, or
b.
Clamp with 600 A if the TA019 is used.
The settings are shown in Figure 10.
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Figure 10: settings of PicoScope for the choice of the current clamp.

4. Set the correct range from the "scale setting" drop-down menu next to channel A : -100A/200A.
5. Set 2 s/div and sampling frequency to 100 kS. In this way it is possible to have a sampling frequency of
5 kHz: sampling refers to the number of samples stored in the total window of 10 divisions that is
displayed on screen: with 2 s/div, as there 10 divisions and then on screen a measure of 20 s will be
shown. In this way, therefore, the frequency will be equal to

𝑓=

Samples
100 𝑘𝑆 100000
=
=
= 5000 Hz
Sampling time
20 𝑠
20 𝑠

PicoScope connections and settings
Channel A scope
Channel A scale setting
Time scale settings
Sampling

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

6. Save the measures in psdata and PDF formats.
In Figure 11 a typical current absorption profile by the compressor during a levelling is shown.

Figure 11: typical compressor current absorption profile during levelling.

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B2: Electrical current absorbed by the valve block
The current measurement absorbed by the valve block of the air suspension system can be done from pin 23 of
connector B of the ASCM module, as shown in Figure 12. Since, in this case, the current values are lower than
those in the B1: current absorbed by the compressor, in addition to the fact that these measurements must be
made at the same time as the current measurement absorbed by the compressor, it is required in this case to use
the current clamp TA018, which has a capacity of 60 A. This clamp is shown in Figure 13.

Figure 12: outline of the wiring diagram of the valve block.

Figure 13: TA018 current clamp.

As the connector X090 shown in B1: Electrical current absorbed by the is more easily accessible than the
connector B of the ASCM, please to measure the current by accessing the yellow-green wiring pin 16 of connector
X090, as shown in Figure 18: pin 8 of connector X090 (grey-green wiring).
Figure 14: pin 16 of connector X090 (yellow-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 measure of current absorbed by the valve block, one should follow the following 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 15.
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.
6. Save the measures in psdata and PDF formats.
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Figure 15: settings of the 60 A current clamp.

PicoScope connections and settings
Channel B scope
Channel B scale setting
Time scale settings
Sampling

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

In Figure 16 the typical current absorption profile by the valve block when performing an Actuator Test is shown.

Figure 16: typical valve block current absorption profile during the execution of an Actuator Test.

B3: Electrical current absorbed by the reversing valves
The measurement of the current absorbed by the reversing valves of the air compressor can be conducted from
pin 46 of connector B of the ASCM module, as depicted in Figure 18. Similar to the case of B2: current absorbed
by the valve block, the current values for the reversing valves are lower compared to those measured in section
B1: current absorbed by the compressor. Additionally, these measurements need to be performed simultaneously
with the measurement of the current absorbed by the compressor. For this purpose, the current clamp TA018 with
a capacity of 60 A is required. Refer to Figure 14 for the depiction of this clamp.

Figure 17: outline wiring diagram of the air suspension compressor.
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Connector X090 shown in B1: Electrical current absorbed by the is more easily accessible than the connector B
of the ASCM, please to measure the current by accessing the grey-green wiring pin 8 of connector X090, as
shown in Figure 18.

Figure 18: pin 8 of connector X090 (grey-green wiring).

The TA018 current clamp can be positioned near the TA0167 or TA019 current clamp, with the latter being utilized
to measure the electrical current absorbed by the air suspension compressor.

To perform the measure of current absorbed by the valve block, one should follow the following 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 15.
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.
6. Save the measures in psdata and PDF formats.

PicoScope connections and settings
Channel B scope
Channel B scale setting
Time scale settings
Sampling

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

In Figure 19 a typical profile of the current absorption by the reversing valves group when performing an Actuator
Test is shown.
The expected values (normal values) are summarized below for compressor, valve block and reversing valves are
summarized below:

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

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Figure 19: typical current absorption profile of the
compressor reversing valve assembly when
performing an Actuator Test.

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Attachment C: summary table of the Vehicle Heights of each Vehicle corner
Table 1: table to register the Vehicle Heights for steps 5, 5, and 6.

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

Before Vehicle
Articulation
Routine
(mm)

After Vehicle
Articulation Routine
(mm)

Before
Actuator Test
(mm)

After Actuator
Test
(mm)

Front Left
Front Right
Rear Left
Rear Right

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