Electronic level adjustment (ELA) diagnosis operational testing

AD32.33-S-3003A

Electronic level adjustment (ELA) diagnosis operational testing

28.8.97

Electronic level adjustment (ELA) diagnosis previous knowledge

AD32.33-S-2001A



Electronic level adjustment (ELA) component arrangement

GF32.33-S-0001-02A



Do not change the loading of the vehicle (entry/exit) during the test procedure.



Some timing parameters may be relatively long, since the vehicle may be fully loaded.

"One-sided filling" of the air bags using the HHT is not possible, since mis-use of the procedure may lead to compressor damage.

a

Battery voltage 11-14 V

b

Fuses in order

c

System completely connected (plug-in connections, leads and pneumatic hoses)

d

HHT connected

AD00.00-S-2000-03A

e

Vehicle parked on level surface

f

Vehicle secured against rolling away (at front axis if possible)

Operational testing

Scope of test

Menu selection 

Operation/requirement

Specified value

Possible cause/remedy

1

Read out fault memory



Fault exists

AD32.33-S-6000A

2

Check inputs



Check all inputs/outputs in sequence (operate buttons, ignition etc. if possible).

Start status: engine OFF, all doors closed

- Ignition: ON

- Starter: operate

- Engine: idle speed

- ELA service button

- Manual button

(Code CL0) Operation: up

- Manual button

(Code CL0) Operation: down

- Stop lamp switch

- Separately open and

close hatch and one or two

sliding doors

- Turn ignition OFF/ON

- Initial startup

- Check speed while

driving slowly or at a

standstill

ON

ON

ON

Depending on operating status: untouched or pressed

Depending on operating status: untouched or pressed

Depending on operating status: untouched or pressed

Depending on brake pedal operating status: ON or OFF

Depending on operating status: OPEN or CLOSED

Control lamp on instrument cluster illuminates for about 2 sec.

Completed

Compare HHT display with display on instrument cluster.

 As of 30 km/h the HHT display is no longer exact.

3

Raise/lower





- Select "raise/lower" function

- Make a note of the left and right output levels and the level difference between the left and right barometric pressure sensors. During the procedure, check the state of the outlet valve and the compressor, and count the transverse shutoff valve changes.

 The control module may be blocked using the HHT during the calibration or raise/lower procedure. The cause is the activation of the low voltage shutoff or the compressor temperature restriction function.

The same applies if a fault is entered in the fault memory during the procedure.

In most cases, the raise/lower procedure can be continued after a short wait.

Raise

- Press button F1 (RAISE)

 Raise for at least 30 sec. so that there are no adverse effects on the significance of the vehicle reaction!

- Stop the raise procedure using the F3 button (STOP) or the HHT will automatically stop the raise procedure after 200 sec.

Analysis results:

- Level change:

Compare level information with start level:

- New level at least 5 mm higher than before.

- Level still within 4 mm range, as before.

Repeat raise procedure and check the tightness of the pneumatic connections.

Left/right barometric pressure sensor connectors may be wrong way round!

Remedy the fault and start over!

- Valve change:

Count the number of valve changes during the lifting procedure (left/right transverse shutoff valve). After completion of the lifting procedure, check the total:

Total > 2

The right/left pneumatic connections or the right/left transverse shutoff valve magnetic connectors are the wrong way round. Re-check with adequate lifting distance.

- Pneumatic connector assignment:

During the lifting procedure, check the level difference between the right/left barometric pressure sensors compared to the first level difference that was calculated:

Difference > old difference + 4 mm

Right/left pneumatic connectors or right/left transverse shutoff valve magnetic connectors are the wrong way round.

- Outlet valve:

OFF

- Compressor:

ON during the lifting procedure, OFF after completion

Lower

- Press F2 button (LOWER)

- Stop lowering procedure after no more than 50 sec. using F3 (STOP).

Analysis results:

- Level change:

Compare level information to start level:

New level at least 5 mm lower than previous.

Level still in range of 4 mm, as before.

Repeat lowering procedure and check operation of transverse shutoff valves and outlet valve if necessary.

Right/left barometric pressure sensor connections wrong way round!

Remedy fault and start over!

- Valve change:

Count the number of valve changes during the lowering procedure (left/right transverse shutoff valves). After completion of the lowering procedure, check the total:

Total > 2

The right/left pneumatic connections or the right/left transverse shutoff valve magnetic connectors may be the wrong way round. Re-check with adequate lowering distance.

- Pneumatic connector assignment:

During the lowering procedure, check the level difference between the right/left barometric pressure sensors compared to the first level difference that was calculated:

Difference > old difference + 4 mm

Right/left pneumatic connectors or right/left transverse shutoff valve magnetic connectors are the wrong way round.

- Outlet valve:

ON during the lowering procedure, OFF after completion

- Compressor:

OFF

4

Compressor type query





- Vehicles with "Raise/lower rear pneumatic suspension" special equipment (Code CL0)

- Vehicles without "Raise/lower rear pneumatic suspension" special equipment

High-power compressor (210 W)

Low-power compressor (130 W)

If parameters not O.K.:

- Re-enter compressor type parameter.

5

Fault memory



Read out fault memory

Remedy existing faults and erase fault memory.

AD32.33-S-4001A

Faults that occur when couplings and connectors are disconnected with the ignition ON or before the control module after-run time has elapsed (approx. 10 sec.) should be erased.

6

Stop operational check



If service mode or manual mode is no longer required after completing the operational check, put the control module back into automatic mode!