VALVE GP-PRIORITY 9P1891 - Caterpillar

ACTIVE Diagnostic Codes
Diagnostic codes are used by the 3176B system to warn the operator of a problem and indicate to the service technician the nature of the problem. Some codes are used only to record an event, and do not indicate problems.An ACTIVE Diagnostic code represents a problem that should be investigated and corrected AS SOON AS POSSIBLE. Repairing the cause of an ACTIVE code will cause the code to be cleared from the ACTIVE Diagnostic Code screen.When an ACTIVE code is generated, the 3176 Check Engine/Diagnostic Lamp will turn On and remain On, blinking every five seconds. If the condition generating the fault occurs only for a brief moment, the lamp will go Off after five seconds and the fault will be LOGGED. Not all diagnostic codes will cause the Check Engine/Diagnostic Lamp to come On, nor will they flash out. After a problem has been investigated or corrected, the related diagnostic code should be cleared from memory.ACTIVE codes may be viewed using an electronic service tool (ECAP), and may also be viewed using the Check Engine/Diagnostic Lamp. The Check Engine/Diagnostic Lamp should not be confused with the Warning Lamp which is used with 3176 Caterpillar Engine Monitoring. Some troubleshooting procedures, such as disconnection of a sensor may cause diagnostic codes. Make sure all diagnostic codes are noted prior to the start of the troubleshooting procedure to avoid confusion.Using The ECAP To Display ACTIVE Codes
A. With key Off, connect an ECAP to the 3176 system via the Data Link Connector.B. Turn key On (engine does not need to be started to view codes).C. Refer to the Operating Manual and Special Instructions for the service tool (listed under 3176 Service Tools) to read the code(s). On the ECAP, the display menu will direct you to the proper screen to display diagnostic messages similar to the example below.
Example ECAP Screen: "Display ACTIVE Diagnostic Messages"LOGGED Diagnostic Codes
When an ECM generates a diagnostic code, it usually logs the code in permanent memory within the ECM. The time the code occurred (in hours on the internal diagnostic clock) is logged along with the code. The logged codes can then be retrieved later or erased using an ECAP service tool. They can be a valuable indicator when troubleshooting intermittent problems.When investigating Logged diagnostic codes, keep in mind: Some troubleshooting procedures, such as disconnection of a sensor may cause diagnostic codes. Make sure all diagnostic codes are noted prior to the start of the troubleshooting procedure to avoid confusion.* Some codes may be sensitive, and may log occurrences that did not result in operator complaints. If the time the code was logged does not correlate to a complaint, there may be nothing to fix.* The most likely cause of an intermittent problem is connections or damaged wiring. Next likely is the component (sensor or injector, for instance). Least likely is the ECM.* Some codes represent "events", not failures. An example of a "Logged Event" is below. The following table lists the