To be notified that a lamp status exists, the pre-alarm for active DTCs must be enabled through
BESTCOMS. When one or more active DTCs exist in the ECU, a lamp status indicating the severity of the
combined DTCs should exist. After the pre-alarm is annunciated (by LED indicator, horn, and/or dial-out),
the operator will know to check the lamp status, active system DTCs, and what relationship the DTCs
have with the parameters. To check the DTC/parameter relationship at the front panel, access the ECU
Parameters menu of the HMI. In BESTCOMS, hover the mouse pointer over the DTC to see its related
parameter.
To use the HMI to view the list of active DTCs, press the Raise/Scroll pushbutton. The next screen to
appear will display the first DTC, the number of DTCs, the Suspect Parameter Number (SPN), the Failure
Mode Indicator (FMI), and the Occurrence Count (OC).
In the DTC screen example of Figure 3-5, the first DTC of five is displayed. The SPN is 111 (coolant
level), the FMI is 1 (low voltage from the sender, thus we have low coolant level), and the OC is 2 (the
engine has had a low coolant level twice before). Refer to the engine manufacturer CAN interface
documentation for specific descriptions of codes.
Figure 3-5. DTC Screen Example
After viewing the last DTC, screen 5 of 5, VIEWED ALL ACTIVE and USE SELECT TO CLEAR will be
displayed. This also applies when viewing previous DTCs.
Clearing the active or previous DTCs, by pressing the Select/Enter pushbutton, will give one of four
responses.
1. A positive acknowledgment that causes ACTIVE DTC(S) HAVE BEEN ERASED to be displayed.
2. A negative acknowledgment that causes ERROR - NEGATIVE ACK and CANNOT ERASE DTC(S) to
be displayed.
3. A timeout for acknowledgment which causes ERROR - ACK TIME OUT and CANNOT ERASE
DTC(S) to be displayed. This occurs when approximately two seconds have elapsed with CAN
working and no positive or negative acknowledgment received.
4. A CAN communication failure causes ERROR - DISCONNECTED and CANNOT ERASE DTC(S) to
be displayed. This occurs when CAN is disconnected or the ECU is not functioning properly.
After viewing the response, the only way to back out of the screen is to press the Previous pushbutton.
The user is then taken back to the Alternate Display mode. Pressing the Display Toggle pushbutton will
take the user to the Menu mode screens. This also applies when viewing previous DTCs.
ECU Parameters Mode
When the optional J1939 communication is enabled, access to the ECU Parameters menu is available.
This menu displays parameters metered from the ECU. Only parameters related to genset applications
are metered from the ECU and displayed here. A submenu for viewing the engine configuration
parameters is also accessible from the ECU Parameters menu.
If a parameter is never sent after communication is established, or the ECU has sent information notifying
the DGC-500 that the parameter is not supported (non-applicable), then the parameter’s screen will be
hidden and skipped when scrolling from screen to screen in the ECU Parameters menu.
If a DTC is associated with one of the parameters, then the screens will function like the Pre-Alarm
screens of the Alternate mode display. When scrolling through the menu, the user is taken to the new
DTC-related screens first. The DTC-related screen will then blink while alternating between the
parameter’s value and the DTC information.
NOTE
Always refer to the engine manual for the meaning of SPN and FMI
combinations, especially for proprietary DTC descriptions.
CURR LAMP STATUS
ENG STOP LAMP ON
3-16 DGC-500 Functional Description 9355400990 Rev H
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