3116 and 3126 HEUI Truck Engines Engine Diagnostics


Caterpillar Electronic Engines have self diagnostic capability. When the system detects a problem, the CHECK ENGINE/DIAGNOSTIC (YELLOW) lamp activates. In most cases a diagnostic code will be stored in permanent memory within the ECM. The diagnostic code can be retrieved by using either of the following methods.

* Caterpillar electronic service tool

Some vehicles have electronic dashboards that provide a direct readout of engine diagnostic codes. If equipped with an electronic dashboard display, follow the instructions that are provided by the vehicle manufacturer in order to retrieve the engine diagnostic codes.

Check Engine/Diagnostic Lamp

The CHECK ENGINE/DIAGNOSTIC (YELLOW) lamp on the vehicle dashboard is used to communicate the status or the operation situations of the electronic engine and the control system.

When the ignition key switch is turned ON, the YELLOW lamp will illuminate for five seconds (as a lamp check). The lamp will also illuminate and flash every five seconds whenever the ECM detects an ACTIVE fault or condition. If the lamp comes ON and continues to flash every five seconds after initial start-up, the ECM has detected a system problem.

The YELLOW lamp is also used for the Idle Shutdown Timer. The lamp will start to flash at a rapid rate 90 seconds before the programmed idle time expires. The engine will shut down after the 90 second interval. To disable the Idle Shutdown Timer, the ALLOW IDLE SHUTDOWN OVERRIDE must be programmed to YES. The clutch pedal or the service brake pedal must be depressed during the final 90 seconds while the YELLOW lamp is flashing. A diagnostic EVENT code, Override of Idle Shutdown Timer, will be logged 1n the ECM.

Diagnostic Flash Code Retrieval

Check Engine/Diagnostic Lamp in Cab

NOTE: The following procedure can be used to determine ACTIVE codes (a constantly flashing lamp indicates an active code), or any codes which occur after the engine is started. The procedure cannot be used to retrieve LOGGED codes which occurred before the ignition key switch was turned ON (i.e. from yesterday or a week ago). A Caterpillar electronic service tool is necessary to retrieve those LOGGED codes.

All ACTIVE codes may be viewed using a Caterpillar electronic service tool or by performing the following procedure.

  1. Turn the Cruise Control ON/OFF switch OFF.

      2. Move the SET/RESUME switch to either position. Hold that position until the YELLOW lamp begins to flash.

The YELLOW lamp will flash to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the diagnostic code. After a two second pause, the second sequence of flashes will identify the second digit of the diagnostic code.

Any additional diagnostic codes will follow (after a pause) and will be displayed in the same manner. Flash Code 55 signals No Detected Faults have occurred since the ignition key switch was turned ON.

For further information, assistance for repairs, or troubleshooting, refer to the Service Manual or consult an authorized Caterpillar dealer.

The following chart lists and describes electronic diagnostic codes.

NOTE: The chart indicates the potential effect on engine performance with ACTIVE flash codes.

Some codes record events or indicate that a mechanical system needs attention rather than indicate a performance problem. Troubleshooting is not required for codes 35, 41, 47 and 55. Code 01 will not flash out. Some codes will limit the operation or the performance of the engine. Refer to the Diagnostic Flash Code chart for these codes.

Operation With Intermittent Diagnostic Codes

If the YELLOW lamp illuminates during engine operation and then shuts off, an intermittent fault may have occurred. Intermittent faults are logged into the permanent memory of the ECM.

In most cases it is not necessary to stop the engine because of an intermittent code. However, we recommend that the operator retrieve the code(s) and refer to the chart in order to identify the nature of the event. The operator should note or document the circumstances (low power, vehicle/engine speed limits, excessive smoke, etc) involved during the time the lamp was ON. Documentation may be useful for future reference, and in order to help troubleshoot the situation.

The most likely cause of an intermittent code is a faulty connection or damaged wiring. Next is a component failure such as a sensor or a switch. The least likely cause is the ECM.

LOGGED diagnostic codes can be a valuable indicator for troubleshooting intermittent problems. A code that is logged repeatedly may indicate a problem that needs special investigation. Codes that are logged only a few times and do not result in operator complaints may not need attention until a scheduled maintenance interval.

Operation With Active Diagnostic Codes

If the YELLOW lamp stays ON during normal engine operation, first ensure that the engine has proper oil pressure, coolant temperature and coolant level. If the engine has the proper oil pressure and the YELLOW lamp is ON, this indicates that the system has identified a situation that is not within specification.

Retrieve the code(s), refer to the Diagnostic Flash Code chart, and follow the Suggested Operator Action (i.e., Shut Down Engine/Vehicle, Service ASAP, or Schedule Service).

The ACTIVE code should be investigated and corrected as soon as possible. Repairing the cause of the code will shut the lamp OFF (if there is only one ACTIVE code).

Engine Monitoring Package

This programmable feature monitors:

* coolant temperature
* inlet manifold air temperature
* coolant level (if equipped with the sensor supplied by the OEM)

Engine Derating

Derate is initiated when the CHECK ENGINE/DIAGNOSTIC lamp flashes, depending on the severity of the condition. The full derate places the following limits on operation.

* The engine power is limited to 90 kW (120 hp)
* The vehicle speed is limited to 72 km/h (45 mph)

Refer to the Service Manual for troubleshooting the system operation. For further information or assistance, consult your Caterpillar dealer.

Customer Specified Parameters

Customer Specified Parameters can be programmed into the ECM to enhance fuel efficiency and operator convenience. Some parameters may affect engine operation and lead to operator complaints about power or performance, even though the engine is performing to specification.

These parameters allow the owner/customer to influence how the vehicle is driven. The parameters can be changed as often as needed. Password protection enables the owner/customer to control the options and who can change the parameters. Refer to LEXT7203, Programming Caterpillar Electronic Truck Engines, for information. Consult with your Caterpillar dealer for detailed instructions on how to program the electronic engine for optimum performance and fuel economy.

A few of the Customer Specified Parameters for the PTO Governor are explained below.

Idle/PTO Vehicle Speed Limit – The maximum vehicle speed at which the Idle/PTO Governor will function [between 0 and 24 km/h (0 and 15 mph)]. If the vehicle speed exceeds the programmed value, the control will exit the Idle/PTO Vehicle Speed Limit mode.

Idle RPM Limit – The maximum engine rpm when the engine is in the Idle Mode. The idle rpm limit is between 600 rpm and the Top Engine Limit (TEL) for the particular engine rating.

Idle/PTO RPM Ramp Rate – The rate of increase or decrease in engine speed (rpm). This parameter determines the rate of ACCEL, DECEL, and RESUME Idle/PTO. The programmable limits are between 5 rpm/second and 1000 rpm/second.


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