Страница 1 мировой engineering стандарты общая спецификация

Page 100
GM WORLDWIDE ENGINEERING STANDARDS
GMW3110
If the setting of diagnostic trouble codes (DTC) has been disabled via the $10, $28, or $AE services, then the
node shall re-enable the diagnostics and take the necessary steps to reinitialize diagnostic counters, flags,
timers, etc in order to prevent false DTCs from being set due to the fact that the algorithm was disabled for
some period of time.
Note: 
It may be necessary for a node to reset certain DTC algorithms or variables used within these algorithms
prior to executing a software reset at the conclusion of a programming event.
An ECU shall send an unsolicited service $20 positive response message any time a TesterPresent ($3E)
timeout (P3
C
) occurs and a programming session is not active.

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Note: 
If a P3
C 
timeout occurs while the ECU is in the process of receiving or transmitting a multi-frame USDT
diagnostic message, the unsolicited service $20 positive response message shall be delayed until after the
multi-frame message (reception or transmission) has completed.
8.5.2 Request Message Definition (Table 75).
Table 75: Request Message Definition
Data Byte Parameter Name
Cvt Hex Value Mnemonic
#1
returnToNormalMode Request Service Id
M
20
SIDRQ
8.5.2.1 Request Message Sub-Function Parameter $Level (LEV_) Definition. 
Because this service is
defined as a single operation, there are no sub-parameters required or valid for the request message.