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

 
$0000 thru $FFFF 
DTC_Index 
This is an index variable used by the background loop for sending level $81 
responses.
 
0 to total_num_local_dtcs 
Level_81_Active 
This is a flag which is used to keep track of whether a response to a level $81 
request is in progress.
 
YES/NO 
Request_Status_Mask 
This variable is used to store the requested status mask to a level $81 request 
and is used by the background function which transmits the responses.
 
$00 thru $FF 
msg_sent 
This is a local variable used to prevent the ECU from attempting to transmit two 
messages in response to a level $81 request in the same pass of the 
background loop.
 
YES/NO 
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GMW3110 
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February 2010 
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Variable/Meaning 
Values 
DTC_Info 
This is an array of data structures used to house DTC specific information within 
a node. The following elements comprise this structure: 
1. DTCH = most significant byte of diagnostic trouble code. 
2. DTCL = least significant byte of diagnostic trouble code. 
3. DTCFT = failure type information associated with the DTC. 
4. DTCSB = status information associated with the DTC (refer to Table E1: 
DTC Status Bit Assignments for more details.) 
To access information in this structure, the following nomenclature is used: 
DTC_Info[x].element, where x = 
m
or 
n
as described above in the data 
dictionary, and 
element
is one of the four types listed above. 
The values for each element 
of the DTC_Info structure 
are described below: 
1. $00 
≤ DTCH 

$FF 
2. $00 

DTCL 

$FF 
3. $00 

DTCFT 

$FF 
4. $00 

DTCSB 

$FF