A self-diagnosis function with fault memory is integrated in the DME control unit which permits certain faults in the injection, ignition and knock regulating systems to be detected and stored.
The DME control unit has a permanent positive connection to prevent deletion of detected and stored faults when the ignition is turned off. Detected faults remain stored in the fault memory for at least 50 engine starts (exception: idle speed switch interruption faults).
If the DME control unit plug or battery is disconnected, the fault memory and system adaption will be cleared.
The vehicles are equipped with a 19-pin plug-in connection in the passenger footwell to allow diagnosis to be performed.
The system tester 9288 or the flashing code tester 9268 (via adapter lead 9268/2) can be connected to this plug-in connection. Operation of the testers is explained in the tester instructions:
The respective test point is supplemented by the corresponding fault flashing code of the tester 9268.
Test point 2 = Idle speed contact (1_12) 2nd digit display "1" fault exists or "2" fault does not exist
The following actual engine data can be read directly in the .Actual value" menu with the system tester 9288 as from tester module version 2.0:
Intake air temperature Ignition timing Oxygen sensor voltage Version code
Idle speed control duty ratio
Engine temperature Engine speed Power supply Air flow sensor signal Load signal
Operating conditions for start of DME diagnosis
Diagnosis may be started with the "ignition on" and with the engine standing still or running at up to 2,000 rpm.
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