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 194 of 336 
8.17.8 Tester implications. 
The tester should only request this service with the ALL NODES request CANId 
($101) and the ALL NODES extended address ($FE).
 
The tester should not enable a programming event if it has received a negative response (from any node) to 
the initiate programming request is sent. 
After enabling a programming event (sending a requestProgrammingMode_HighSpeed request followed by an 
enableProgrammingMode message), the tester must not transmit any messages for 50 ms. The test device 
must also initialize its protocol converter hardware to high speed operation within 30 ms from the time that the 
enableProgrammingMode request message was successfully transmitted on the data link. 
TesterPresent (Mode $3E) messages must be sent to all nodes at least once every P3
C
ms to keep the 
programming mode active, otherwise the nodes shall return to normal operation (same as receiving a 
ReturntoNormalMode $20 request or a P3
C
timeout). 
The tester must be capable of returning the bus to normal speed mode by issuing a mode $20 
ReturntoNormalMode message. After sending a mode $20 request (when the link is in high speed mode), the 
tester should wait 1 s before transmitting any messages to allow devices to reset and to prevent possible bus 
error or bus off conditions from occurring. 
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GM WORLDWIDE ENGINEERING STANDARDS 
GMW3110 
© Copyright 2010 General Motors All Rights Reserved 
February 2010 
Page 195 of 336 
8.18 ReadDiagnosticInformation ($A9) Service. 
This service allows a tester to read the status of 
node-resident Diagnostic Trouble Code (DTC) information from any controller, or group of controllers within a 
vehicle. This service allows the tester to do the following:
 
1. Retrieve the status of a specific DTC and FaultType combination. 
2. Retrieve the list of DTCs that match a tester defined DTC status mask. 
3. Enable a node resident algorithm which periodically calculates the number of DTCs that match a tester 
defined DTC status mask. The ECU shall send a response message each time the calculation yields a 
different result than the one calculated the previous time.