NUT 1217668 - Caterpillar

Diagnostic Codes
Diagnostic codes alert the operator that a problem in the electronic system has been detected. Diagnostic codes also indicate the nature of the problem to the service technician. Caterpillar Electronic Technician (ET) is a software program that is designed to run on a personal computer. Diagnostic codes may be viewed on a personal computer that has Cat ET software. Diagnostic codes may consist of the module identifier (MID), the component identifier (CID), and the failure mode identifier (FMI).Component Identifier (MID) - The MID is a three-digit code that identifies the ECM that generated the diagnostic code. For example, the MID 036 identifies the engine ECM.Component Identifier (CID) - The CID is a number with three or four digits. The CID indicates the component that generated the code. For example, the CID number 0001 identifies the fuel injector for the number one cylinder.Failure Mode Identifier (FMI) - The FMI is a two-digit code that indicates the type of failure. Refer to Table 2 for a complete list of the two-digit codes. Refer to Table 2 for a description of the failure.
Table 2
FMI Failure
00 Data is above the normal range.
01 Data is below the normal range.
02 Incorrect signal
03 Voltage is above the normal range.
04 Voltage is below the normal range.
05 Current is below the normal range.
06 Current is above the normal range.
08 Abnormal signal
09 Abnormal update
12 A device or a component failed.
13 A component is out of calibration. Refer to Table 1 for a complete list of the diagnostic codes and the appropriate troubleshooting procedure.Do not confuse diagnostic codes with event codes. Event codes alert the operator that an abnormal operating condition such as low oil pressure or high coolant temperature has been detected. If an event code is active, refer to Troubleshooting, "Event Code List".
Illustration 1 g01365757
Example of the typical operating range of a sensor
(1) This area represents the normal operating range of the engine parameter.
(2) In these areas, the engine is operating in an unsafe operating range of the monitored parameter. An event code will be generated for the monitored parameter. The sensor circuit does not have an electronic problem. Refer to Troubleshooting, "Event Code List" for additional information on event codes.
(3) In these areas, the signal from the sensor is outside of the operating range of the sensor. The sensor circuit has an electronic problem. A diagnostic code will be generated for the sensor circuit.Active Diagnostic Codes
An active diagnostic code represents a problem with the electronic control system. Correct the problem as soon as possible.When the engine's ECM generates an active diagnostic code, the "Active Alarm" indicator ("Engine Control Alarm Status" on Cat ET) is activated to alert the operator. If the condition that generated the code is momentary, the message disappears from the list of active diagnostic codes. The diagnostic code becomes logged.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