LINK AS 4928532 - Caterpillar

fault is any condition that does not conform to the rules that the GSC+ operates. A fault can be active or a fault can be inactive. An active fault is a fault that is occurring now. An inactive fault is a fault that has previously occurred. Some examples of faults are listed below.
Coolant temperature is 123°C (254°F). This is a high water temperature fault.
Engine speed is 4500 rpm. This is an engine overspeed fault.
There is a broken wire in the engine harness. This is a diagnostic fault.
There is a failed oil pressure sensor. This is a diagnostic fault.An amount of severity is attached to every fault. The amount of severity also describes the GSC+ response to a fault. Faults are either alarm faults or shutdown faults. Alarm faults are not critical. Shutdown faults are critical.An alarm fault provides the operator with an early warning to the operator of a possible future shutdown fault. For an alarm fault, the GSC+ automatically activates alarm mode and the fault alarm indicator FLASHES. See System Operation, "Alarm Mode" for further information.A shutdown fault tells the GSC+ to shutdown the engine in order to prevent engine damage. The GSC+ automatically activates shutdown mode which shuts down the engine. The GSC+ then flashes the corresponding indicator. See System Operation, "Shutdown Mode" for more information.Most faults have a code. There are three types of fault codes. The type is obtained from the GSC+ input that is involved. The three types of fault codes are listed below.AL Fault Codes - The AL fault codes are shown as AL1 through AL15 (AL18 on EMCP II+P) on the upper display. The AL fault codes include specific engine conditions. An example of an AL fault code is the low engine oil pressure alarm. AL fault codes also include protective relaying functions. Another example of an AL fault code is the underfrequency fault.SP Fault Codes - The SP fault codes are shown as SP1 through SP4 on the upper display.Diagnostic Codes - Diagnostic codes are shown as numeric values. Diagnostic codes are identified by the illumination of "CID FMI" on the upper display.There is an exception. There are no fault codes for the shutdown faults that correspond to the dedicated shutdown indicators. The shutdown faults are identified to the operator by the nearest dedicated fault shutdown indicator. Low oil pressure is an example of a dedicated shutdown indicator.