General

General




A malfunction that is detected is assessed by the control module's self-diagnosis. First after, e.g., a certain time, a certain number of driving cycles, certain driving/operation or other conditions, the control module decides if it is a real malfunction or not.
When self-diagnosis has determined that a real malfunction exists, you can say that the malfunction is confirmed and the malfunction is stored in the control module's trouble code memory in the form of diagnostic trouble codes.
If a malfunction disappears, the diagnostic trouble code will remain for a tome in the diagnostic trouble code memory, but the status of the diagnostic trouble code changes. How long the diagnostic trouble code is stored in the diagnostic trouble code memory is different from control module to control module, as well as between different vehicle models (generation of vehicle model).
In some systems the diagnostic trouble code will be stored until it is erased with the diagnostics tool. In other systems the diagnostic trouble code is erased automatically by the control module after, e.g., a certain number of malfunction-free driving cycles. A new driving cycle (operation cycle) is usually started every time the ignition is turned on.

Information about the nature of the malfunction is stored for every diagnostic trouble code:
- when the malfunction was detected (frozen values, counters)
- what the driving conditions were at the time (frozen values)
- status for the test (diagnosis) (status identifier)
- how frequent the malfunction is (counter).
Exactly what is stored is different from control module to control module, , as well as between different vehicle models (generation of vehicle model).
If the system is provided with warning light, it is lit when the ignition key is turned to position II. The warning light will go off after a certain number of seconds when no malfunction is detected on the control system.
The warning light will be on in case of a malfunction of the control system. The warning light will be lit first after the malfunction is confirmed as a real malfunction.