LS V8-3.9L VIN A (2003)
messages are the result of an input to one module being transmiffed to another module that carries out a vehicle function. messages may contain
information that commands a module to perform a function, while other messages may provide information related to vehicle status that will allow or not
allow a function to be performed. Depending on the command, a module may be able to accommodate the command entirely on its own or it may require
another module to operate in a certain fashion to achieve the desired initial command. This is all communicated through the SCP Link.
For example, by turning on the headlamp switch the ICM receives the command (input) from the switch to activate all exterior lamps. The ICM does not
directly control the exterior lamps, but instead will send a message out over the SCP link telling the FEM and REM that the customer has requested all
exterior lamps be turned on. The FEM will receive this message and provide a ground activating all the lamps it has within its control in the front of the
vehicle. Simultaneously, the REM will receive the same message over the SCP link requesting that all lamps in the rear of the vehicle associated with
headlamp operation be activated.
NOTE
DO NOT PREMATURELY DETERMINE THAT THE SOURCE MODULE IDENTIFIED IS THE CAUSE OF THE BATTERY DRAIN
CONDITION. IN MOST CASES, THE MESSAGE CAN BE TRACED TO A FAULTY COMPONENT SENDING A FALSE INPUT ON THE
SCP LINK. THIS CONDITION MAY NOT ALLOW A MODULE TO POWER DOWN. IF THE ERRANT MESSAGE OCCURS AFTER
POWER DOWN, IT MAY WAKE UP A SYSTEM THAT HAS POWERED DOWN.
6.
The following function keys are active when monitoring the SCP Link:
^
RESET: Clears the screen while the monitor is running
^
FLTR: Turns the filter feature ON or OFF as indicated by the FLRT display in the upper right screen
^
SETUP: When SETUP is pressed, the filter setup screen will appear. This will allow the operator to specify the capture of only certain
messages by either its source (particular module) or function
^
START: The START key will start the NGS Classic in monitor mode, and display all traffic on the link. The START key will now be
displayed as STOP. Pressing the STOP key will stop the monitor from reading any further traffic on the SCP link
NOTE
PRESSING THE START KEY AGAIN WILL CLEAR THE SCREEN OF ALL CAPTURED MESSAGES.
NOTE
THE NGS Classic WILL CONTINUOUSLY CAPTURE MESSAGES BUT WILL ONLY DISPLAY UP TO 100 MESSAGES AT ONE TIME.
ONCE 100 MESSAGES ARE STORED, THE FIRST MESSAGE WILL BE DELETED FROM THE LIST.
THE MONITOR OPERATES ON THE "FIRST IN, FIRST OUT" PRINCIPAL.
NOTE
THE PCM AND ABS SHOULD NOT DISPLAY ANY FORM OF MESSAGE ACTIVITY WITH THE KEY IN THE OFF POSITION. IF ANY
PCM OR ABS MESSAGES ARE DETECTED AT THIS TIME, CHECK FOR VOLTAGE ON CIRCUITS WHICH SHOULD ONLY HAVE
