
RENR5622 11
Troubleshooting Section
i02319628
Self-D iagn ost ics
SMCS Code: 1901
-038
Diagnostic Cod
es
The engine’s Electronic Control Module (ECM) has
the ability to
monitor the circuitry to the ECM and the
circuitry from the ECM to the engine’s components.
The ECM also has the ability to monitor the engine’s
operating con
ditions. If the ECM detects a problem, a
code is generated.
There are two
categories of codes:
•
Diagnostic Code
•
Event Code
Diagnostic C
ode – A diagnostic code indicates an
electrical problem such as a short or an open in the
engine’s wiring or in an electrical component of the
engine.
Event Code – An event code is generated by the
detection o
f an abnormal engine operating condition.
For example, an event code will be generated if the
oil pressure is too low. In this case, the event code
indicates t
he symptom of a problem. Event codes
indicate mechanical problems rather than electrical
problems.
Codes can have two different states:
•
Active
•
Logged
Active Codes
An active c
ode indicates that a problem is present.
Service the active code first. For the appropriate
troubleshooting procedure for a particular code, refer
to the foll
owing troubleshooting procedure:
•
Troubleshooting, “Diagnostic Code List”
•
Troubleshooting, “Event Code List”
Logged Cod
es
The codes are logged and stored in the ECM
memory. T
he problem may have been repaired
and/or the problem may no longer exist. If the
system is powered, it is possible to generate an
active di
agnostic code whenever a component is
disconnected. If the component is reconnected, the
code is no longer active but the code may become
logged.
Logged codes may not indicate that a repair is
needed. The pro
blem may have been temporary.
Logged codes may be useful to help troubleshoot
intermittent problems. Logged codes can also be
used to review
the performance of the engine and
of the electronic system.