The system test permits simple, visual assessment and inspection of the modules belonging to the instrument cluster. The system test can be triggered via "test function 2" and with the control unit functions (Instrument cluster - activate components - self-test).
All test functions, apart from test numbers one and two, are interlocked and must be released by means of test function number nineteen.
System test (Test No. 2): Test function number 2 is possible only in ignition key position 1 (terminal R) or position 2 (terminal 15) when no position signals are determined and the engine is not operating.
Procedure: Press and hold (approx. 5 s) the trip recorder reset button with terminal R "ON" until "__tESt__1._" appears in the instrument cluster display. The corresponding test (system test corresponds to test 2 "__tESt__2._") can be selected by pressing/releasing the button again within 1 second. The first subfunction of the test selected then appears after approx. 1 second. The subfunction (the system test has no further subfunction) of the corresponding test can be selected by pressing the button again. Since there are no further subfunctions associated with test 2 (system test), the system test is triggered after the "__tESt__2.0" display appears and the trip recorder button is pressed. If the test is a locked test (test 3 to 21) the lock is released by pressing the trip recorder button when "_L_oFF" appears in the display. The display then jumps to test 0 so that the corresponding test can be selected by briefly pressing the button.
During the course of the system test the pointer instruments are moved uniformally from the left stop to the right stop within about 5 seconds and back to the zero position within a further 4 seconds. The indicator and warning lights that can be actuated remain activated during the instrument test (exception: The engine oil level indicator lamp lights only during every second cycle, general brake warning lamp and brake assistant warning HBA alternate during each cycle).
These elements are:
Indicator and warning lamps: