Classic to Check For Unwanted Activity
USING THE NGS CLASSIC TO CHECK FOR UNWANTED ACTIVITYThis section advises how to use the NGS Classic tester to check the SCP Link for this type of unwanted activity. The NGS Classic Service Card is equipped with a SCP Link Monitor Tool which allows the technician the ability to monitor the communication, or traffic, between all modules equipped in the vehicle that use the SCP Link. Many of the vehicle functions are accomplished as a result of the communication between modules.
NOTE
THE NGS Classic WILL CONSUME 507mA AT 12.6V. IF MEASURING CURRENT DRAIN WITH THE NGS Classic INSTALLED, 507mA MUST BE SUBTRACTED FROM THE CURRENT DRAIN DISPLAYED ON THE DVOM TO DETERMINE THE ACTUAL AMOUNT.
1. Using NGS Classic Service Function Card version 10.1 or higher, select SCP LINK MONITOR TOOL from the main menu.
2. With the ignition key in the OFF position, connect the NGS Classic to the 16-pin Data Link Connector.
3. Select the SCP LINK MONITOR TOOL from the main menu and press the START key.
4. At this point, a normally operating vehicle should have no messages present in the SCP Link. If no messages are present, leave the NGS Classic connected to the vehicle and periodically check for SCP activity. If the concern is intermiffent, it may take some time before the suspect component behaves in an undesirable fashion. If a message is eventually observed, continue with Step 5 in this section. Because of the excessive drain caused by the NGS Classic, it may be necessary to connect a battery charger to prevent a dead battery.
5. If messages are present, press the STOP key. Scroll through the messages on the screen using the scroll dial. The following information will be displayed in order on the NGS Classic. Match this information with the data on the Message List found at the end of this article.
NOTE
WHEN USING THIS TOOL FOR 2003 - 2006 VEHICLES, SOME OF THE MODULE CODES MAY NOT SHOW ON THE CHART. ENOUGH INFORMATION FROM THE SOURCE SHOULD BE AVAILABLE FOR MODULE IDENTIFICATION AND CIRCUIT AFFECTED. EXAMPLE: FCU = FRONT CONTROL UNIT (RADIO).
^ FNCT (FUNCTION): Displays the two (2) digit ID that represents a category of function to be carried out by the module(s) receiving the message. Match this ID with the Function column on the message list
^ SRC (SOURCE): Displays the module acronym responsible for sending the SCP message. Match the module source displayed on the NGS Classic to that on the source column of the message list
^ DATA 01 - 06: Displays more specific information related to the function. Match these characters with the data on columns 1-7 of the message list, along with the source observed, to define the message being viewed on the NGS Classic
^ FLTR (FILTER): Displays the current status of the FILTER function. You may manipulate the NGS Classic to capture messages that are sent from a particular or chosen module (Source) or Function.
Compare the messages received on the NGS Classic to the message list tables at the end of this article. These will help determine the function, source and name of the message read from the SCP Link. The message list tables provide all possible SCP Link messages listed in order by Source. Most 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 POWER WHEN THE KEY IS ON OR IN THE CRANK POSITION.