Страница 1 мировой engineering стандарты общая спецификация

Limited Duration Latching DTCs (Figures E3 and E4): 
Once the Current status has been set to true, it

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WORLDWIDE ENGINEERING STANDARDS General Motors Local Area Network Enhanced Diagnostic Test Mode Specification
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February 2010
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remains set to “True” regardless of the results of the diagnostic test until a specified event (e.g., power up
reset) occurs.
Note: 
The DTC is cleared when a clear diagnostic information command is received. Since the DTC is
latched, the diagnostic algorithm does not run. Therefore, the repair cannot be verified unless the specified
event occurs (e.g., ignition is cycled).
•
Permanently Latched DTCs (Figures E5 and E6): 
Once the Current status has been set to true, it
remains set to true regardless of the results of the diagnostic test. This type of DTC cannot be permanently
cleared and requires ECU replacement. The DTC can be temporarily cleared using a scan tool, but the
DTC returns at the next power up of the ECU.
Powertrain DTCs are also categorized into three main categories; Type A, Type B, and Type C (there is a
fourth category for DTC not supported that is not illustrated here, as these DTCs are in the ECU software but
are not run) based upon illumination of the Malfunction Indicator Lamp (MIL).
Note: 
Due to varying regional requirements, the following tables cannot illustrate all possible cases. These
tables are provided as examples and, in case of a conflict, do not supersede any documented diagnostic
requirements.
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Type A DTCs (Figures E7, E8, and E9): 
The ECU sets the status current, history, and requests
illumination of the malfunction indicator lamp (MIL) when the diagnostic runs and fails. The current status
is cleared when a Test Pass is reported but the MIL remains illuminated for 3 consecutive ignition cycles,
depending on the DTC, when the diagnostic runs and does not fail.
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