HOW TO USE ON-BOARD DIAGNOSTICS - CONTINUED
UNDERSTANDING THE DIAGNOSTIC CODE BREAKDOWN
N OT E
Some procedures may generate new diagnostic codes. Before any procedures are performed, make a list of
all active diagnostic codes in order to determine system problems. Clear logged diagnostic codes caused by
procedure itself once each procedure is complete.
When an ECM detects an engine problem, it generates a diagnostic code. There are two types of diagnostic codes: fault
codes and event codes. Fault codes indicate a problem with electronic control system. Event codes identify the symptoms of
operational problem and indicate how the machine will operate until the problem is solved.
Fault and event codes may be classified as "active" or "logged". For active codes, the ECM records the code itself and a
brief description. For logged codes, the ECM records the hour of first occurrence, the hour of last occurrence, and the total
number of occurrences, using the ECM's internal diagnostic clock.
A diagnostic code can be broken into the following four parts:
Type of Code. The screen display will show "A" for active, "E" for event, or "Blank" for logged.
Module Identifier (MID) or Event Identifier (EID).
MID identifies which ECM detected diagnostic code. Each ECM on machine has a unique two- or three-digit
MID. The engine ECM, designation is 036, and the Machine/Powertrain ECM, designation is 081 for 924G. Refer
to Table 1 in WP 0007 00 for a complete list of fault codes for the Engine ECM. Refer to Table 2 of WP 0007 00
for a complete list of fault codes for the Machine/Powertrain ECM.
The EID identifies an abnormal operating condition. Refer to Table 3 in WP 0007 00 for a complete list of event
Component Identifier (CID). CID is a number with four digits which indicates component generated code. For exam-
ple, CID number 0017 identifies the fuel shutoff valve. Any component that can generate a diagnostic code is assigned a
Failure Mode Identifier (FMI). FMI is associated with either an engine or machine MID code and indicates the type of
sensor failure. The FMI is the last two digits of the diagnostic code. Refer to Table 1 in this work package for an expla-
nation of FMI codes. FMI codes are defined by SAE standards.
MODULE IDENTIFIER (MID)
081 = MACHINE ECM
COMPONENT IDENTIFIER (CID)
036 = ENGINE ECM
TYPE OF CODE
"A" FOR ACTIVE,
"BLANK" FOR LOGGED,
"E" FOR EVENT
INSTRUMENT PANEL SHOWING ACTIVE DIAGNOSTIC CODE DISPLAY