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 248 of 336 
SPS_TYPE_B and SPS_TYPE_C ECUs are programmable ECUs that are missing some element of their full 
combination of operational software and calibrations, or are executing boot software due to a memory error. An 
ECU which is missing calibrations (or is missing operational software and calibrations) may, or may not, have 
permanent diagnostic CAN Identifiers preprogrammed. An SPS programmable ECU which is not fully 
programmed and is used on a single platform would most likely have its permanent diagnostic CAN Identifiers 
preprogrammed. An SPS programmable ECU which is not fully programmed and can be used in multiple 
platforms, may not have the permanent diagnostic CAN Identifiers preprogrammed unless all of the platforms 
can standardize the CAN Identifiers used by that ECU (or multiple parts are released to accommodate the 
differences in CAN Identifiers between platforms). An SPS_TYPE_B ECU meets the above criteria and has its 
permanent diagnostic CAN Identifiers preprogrammed. An SPS_TYPE_C ECU meets the above criteria and 
does not have its permanent diagnostic CAN Identifiers preprogrammed. SPS_TYPE_B and SPS_TYPE_C 
ECUs shall not attempt to participate in normal communication message exchange. 
Note:
An ECU executing boot software due to a memory fault is considered to be SPS_TYPE_B if permanent 
diagnostic CAN Identifiers are comprehended in the boot software. If the permanent diagnostic CAN Identifiers 
are not comprehended in boot software, then the ECU is considered SPS_TYPE_C. 
If permanent diagnostic CAN Identifiers are preprogrammed, an SPS programmable ECU shall respond to all 
diagnostic requests which contain one of the permanent diagnostic CAN Identifiers supported by the ECU 
(SPS_TYPE_A and SPS_TYPE_B). If permanent diagnostic CAN Identifiers are not preprogrammed 
(SPS_TYPE_C), the ECU shall not respond to diagnostic request messages until diagnostic responses are 
enabled. While diagnostic responses are disabled, an SPS_TYPE_C ECU shall only receive and process (but 
not respond to) diagnostic messages addressed to it with the AllNodes request CANId and an extended 
address of AllNodes. The process of enabling diagnostic responses is described in section 9.1.1 of this 
specification. 
At the conclusion of a programming event, all ECUs on a given subnet shall perform a software reset.
Note:
The software reset allows an ECU which was just programmed to begin executing the new operational 
software and calibration data downloaded. In addition, the reset of all devices synchronizes the start-up of 
normal communications. 
A programming event is considered to have concluded upon receipt of a valid ReturnToNormalMode ($20) 
request message, or if a TesterPresent timeout occurs. The tester must ensure that the TesterPresent service 
messages are sent on all GMLAN subnets simultaneously (as close as possible) to ensure that all subnets 
would exit a programming event at the same time should a TesterPresent timeout occur. The same logic 
applies to the tester when sending a ReturnToNormalMode message to end a programming event.