
50 RENR9348-01
Troubleshooting Section
Logged Diagnostic Codes
When the ECM generates a diagnostic code, the
ECM logs the code in permanent memory. The
ECM has an internal diagnostic clock. Each ECM
will record the following information when a code is
generated:
•
The hour of the first occurrence of the code
•
The hour of the last occurrence of the code
•
The number of occurrences of the code
This information is a valuable indicator for
troubleshooting intermittent problems.
A code is cleared from memory when one of the
following conditions occur:
•
The service technician manually clears the code.
•
The code does not recur for 100 hours.
•
A new code is logged and there are already ten
codes in memory. In this case, the oldest code is
cleared.
Some diagnostic codes may be easily triggered.
Some diagnostic codes may log occurrences that
did not result in complaints. The most likely cause
of an intermittent problem is a faulty connection
or damaged wiring. The next likely cause is a
component failure. The least likely cause is the failure
of an electronic module. Diagnostic codes that are
logged repeatedly may indicate a problem that needs
special investigation.
Note: Always clear logged diagnostic codes after
investigating and correcting the problem which
generated the code.
i02419262
Diagnost
ic Code Cross
Reference
SMCS Code
: 1900
Problems with the electronic control system are
reporte
d via the following different types of codes:
SPN/FMI codes, diagnostic codes, and event codes.
For info
rmation on SPN/FMI codes, refer to
Troubleshooting, “Diagnostic Codes”.
For info
rmation on diagnostic codes, refer to
Troubleshooting, “Diagnostic Codes”.
For information on event codes, refer to
Troubleshooti
ng, “Event Codes”.