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

Procedure 6: 
(Additional checks for ECUs that support dynamic DPIDs.)
 
1. Verify that a dynamic DPID can be redefined using the service $2C while that DPID is currently in the 
periodic scheduler. Verify that the data is correct for the newly defined DPID by the second transmission of 
that DPID after the $2C positive response. (The first response of that DPID may be invalid since the DPID 
may have already been queued for transmission prior to the redefinition). 
2. Request a dynamic DPID prior to defining its contents via the $2C service. Verify that a positive response 
is sent with no data after the DPID number. 
3. Repeat step 2 for all supported one shot and periodic rates. 
Procedure 7: 
(Additional checks if the ECU supports negative response code $78.)
 
1. Create conditions under which the ECU should return the $7F $AA $78 response. Send a valid request for 
this service (including applicable sub-function parameter) and verify that the $7F $AA $78 response is 
received followed by the appropriate final response within the P2
C*
timing window. 
2. Repeat step 1 of this procedure for each possible reason an ECU would send the negative response with 
response code $78. Verify this for each applicable supported sub-function parameter. 
8.19.8 Tester Implications. 
It is recommended that a tester use this service with physical addressing. 
Functionally addressed requests for this service may result in unwanted negative response messages from 
one or multiple ECUs. 
Positive response(s) to this service are formatted as UUDT messages. Since it is possible for multiple UUDT 
responses to be sent as a result of a single request, the tester must ensure that it properly handles the timing 
requirements outlined in the description section of this service for each available sub-function.
The test device shall send a Service $3E message at least once every P3
C
ms when using any of the periodic 
rates of service $AA, otherwise the device will exit the periodic transmission as if receiving a Service $AA 
sub-function parameter $00 request (without DPIDs). 
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