This function is used to check that there is no leakage in the retarder and to check the air pressure sensor's function.
Air leakage is easiest to find by listening, or with soapy water.
Test conditions:
Ignition on, engine off.
Parking brake applied.
Air pressure in transmission between 650 and 1,000 kPa.
Battery voltage above 20V.
Procedure:
Start the function.
Press "Start" to pressurize the retarder.
Check that the air pressure sensor shows reasonable values.
Listen for leakage, use soapy water if needed, to easier find any leakage.
Press "Stop" to release the pressure in the retarder.
Finish the test by pressing "OK".
The function is done.
If the function fails, check the test conditions and repair any faults.