General Specification Electrical Function gmw3110 General Motors Local Area Network Enhanced Diagnostic Test Mode Specification

GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 44 of 336 
Note:
“Disable” in this case means preventing the value of the timer from being modified during subsequent 
processing loops. 
The diagnostic application exits this state and enters the DIAG_MODE_ACTIVE state if a diagnostic request is 
received which activates Diagnostic Mode. The diagnostic application enters the DIAG_ACTIVE_TIMER_ON 
state from this state once the last diagnostic service has finished. When transitioning to the 
DIAG_ACTIVE_TIMER_ON state, the Appl_Diag_VN_Timer is enabled. 
Note:
“Enable” in this case means allowing the value of the timer to be modified during subsequent processing 
loops. 
5.2.4.4 DIAG_ACTIVE_TIMER_ON State. 
The diagnostic application shall enter this state from the 
DIAG_ACTIVE_TIMER_OFF state once the last diagnostic service has finished. The diagnostic application 
shall remain in this state until either a new diagnostic request is started (which transitions the application back 
to the DIAG_ACTIVE_TIMER_OFF state) or the Appl_Diag_VN_Timer times out. The diagnostic application 
shall deactivate the application triggered diagnostic VN and transition to the DIAG_INACTIVE state once the 
Appl_Diag_VN_Timer times out. 
5.2.4.5 DIAG_MODE_ACTIVE State. 
The diagnostic application shall enter this state anytime Diagnostic 
Mode is active and shall remain in this state as long as Diagnostic Mode remains active. The 
Appl_Diag_VN_Timer shall remain disabled while in this state. Upon termination of Diagnostic Mode, the 
diagnostic application shall transition to the DIAG_ACTIVE_TIMER_OFF state. 
5.2.5 Activation of the Application Triggered Diagnostic VN. 
The application triggered diagnostic VN is 
activated when the diagnostic application is in the DIAG_INACTIVE state and a diagnostic request is started. 
Once in the DIAG_INACTIVE state, the tester can send a diagnostic request which is made up of one or 
multiple frames. Upon receipt of each SingleFrame (SF) diagnostic request, or the FirstFrame (FF) of a 
multi-frame diagnostic request, the network layer shall provide an indication to the diagnostic application. 
When the diagnostic application is in the DIAG_INACTIVE state and a SF or FF indication is received from the 
network layer, the application shall notify the GMLAN Handler that the application triggered diagnostic VN is 
requested to be active. 
Figure 12 illustrates how the application triggered diagnostic VN is activated based on receipt of a FirstFrame 
of a diagnostic request. In the figure, a wake-up (shown as WuP) is generated by the tester when it is first 
plugged in to ensure that all nodes transition to (or remain in) the COMM_ACTIVE state (refer to Figure 10) 
and that the diagnostic application transitions into (or remains in) the DIAG_INACTIVE state. Upon receipt of 
the FirstFrame indication (N_USData_FF.ind) from the Network Layer, the diagnostic application tells the 
handler to activate the application triggered diagnostic VN.