PIN 2G8769 - Caterpillar

The Electronic Control Module (ECM) can detect faults in the electronic system and with engine operation. A self-diagnostic check is also performed whenever power is applied to the ECM.When a fault is detected, a diagnostic trouble code is generated. This code conforms to the SAE J1939 standard. An alarm may also be generated.Diagnostic Trouble Code - When a fault in the electronic system is detected, the ECM generates a diagnostic trouble code. The diagnostic trouble code indicates the specific fault in the circuitry.Diagnostic codes can have two different states:
Active
LoggedActive Code - An active diagnostic code indicates that an active fault has been detected by the control system. Active codes require immediate attention. Always service active codes prior to servicing logged codes.Logged Code - Many generated codes are stored in the permanent memory of the ECM. The codes are logged for 100 operating hours unless a code is cleared by use of the electronic service tool.Logged codes may not indicate that a repair is needed. The fault may have been temporary. The fault may have been resolved since the logging of the code. If the system is powered, an active diagnostic trouble code may be generated whenever a component is disconnected. When the component is reconnected, the code is no longer active. Logged codes may be useful to help troubleshoot intermittent faults. Logged codes can also be used to review the performance of the engine and the electronic system.