C27 Generator Set Engines Caterpillar

Diagnostic Codes

Diagnostic codes alert the operator that a problem in the electronic system has been detected. Diagnostic codes are also used to alert the operator that abnormal operating conditions, such as low oil pressure or high coolant temperature, have been detected. For information that is related to the trip point and delay time settings for these codes, refer to Troubleshooting, "Engine Monitoring Parameters".

Diagnostic codes are used by the service technician to identify the nature of the problem. The technician must have access to a diagnostic tool in order to read diagnostic information.

CAN Data Link

The CAN data link is used by the Electronic Control Module (ECM) to communicate with control modules, display modules, and service tools. The CAN data link is referred to as the J1939 data link. When a diagnostic code is activated, the ECM can transmit information about the diagnostic code over the J1939 data link to these devices. The diagnostic code will be displayed as a two-element code. The following terms describe the elements of the code:

Suspect Parameter Number (SPN) - The SPN is a code which is assigned to each component in order to identify data via the data link to the ECM.

Failure Mode Identifier (FMI) - The FMI indicates the type of failure.

Refer to Table 1 for a complete list of the diagnostic codes and the appropriate troubleshooting procedure.

Information for Diagnostic Codes

Table 1 is a list of the diagnostic codes for the engine. The diagnostic codes are cross-referenced with the appropriate procedure that can be used to troubleshoot the code.

Portions of this material are reprinted with permission from SAE J1939DA_201607^© 2016 SAE International. SAE International is not responsible for any use or translation of this material, in whole or in part. Please contact SAE International to obtain a complete copy of SAE J1939DA_201607, the official definitive source of this standard.

Cross-Reference from the J1939 Code to the Appropriate Circuit Test

Active Diagnostic Codes

An active diagnostic code represents a problem with the electronic control system. Correct the problem as soon as possible.

When an active diagnostic code is generated, the "Active Alarm" indicator ("Engine Control Alarm Status" on Caterpillar Electronic Technician (ET)) is activated. The indicator is used 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.

Refer to Illustration 1 for an example of the operating ranges of a sensor.

Illustration 1	g01785898
Example of the typical operating range of a sensor (1) This area represents the normal operating range of the engine parameter. (2) In this area, the engine is operating in an unsafe operating range of the monitored parameter. A diagnostic code will be generated for the monitored parameter. The sensor circuit does not have an electronic problem. Refer to Troubleshooting, "Engine Monitoring Parameters" for additional information on these codes. (3) In these areas, the output voltage of the sensor is too high or too low. The voltage is outside of the normal range. The electronic problem will generate a diagnostic code.

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.

Logged codes are listed in chronological order. The most recent code is listed first.

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.

Troubleshooting

Before diagnosing an active code and to provide basic troubleshooting of the engine, perform the following steps in order to diagnose a malfunction:

1. Download a "Product Status Report" from the ECM. The report provides a record of the current state of the engine.

2. Obtain the following information about the complaint:

   • The engine code and the time of the code

   • Determine the conditions for the code. The conditions will include the engine rpm and the load.

   • Determine if there are any systems that were installed by the dealer or by the customer that could cause the code.

   • Determine whether any additional codes occurred.

3. Verify that the complaint is not due to normal engine operation. Verify that the complaint is not due to error of the operator.

4. Narrow the probable cause. Consider the operator information, the conditions of operation, and the history of the engine.

5. Perform a visual inspection. Inspect the following items:

   • Fuel supply

   • Oil level

   • Oil supply

   • Wiring

   • Connectors

If an electrical problem is intermittent, check that the connectors in the circuit are in good repair. Refer to Troubleshooting, "Electrical Connectors - Inspect".