EMCP3 Engine Underspeed Warning Caterpillar

System Operation Description:

If the engine speed drops below the engine under speed threshold set point value, the under speed timer will begin timing. When the timer expires, the engine under speed event is made active, if the engine speed has been below the threshold level continuously while timing. If the engine speed rises above the engine under speed threshold, the engine under speed event will be made inactive. The timer will be reset.

If an under speed condition is detected, "ENGINE UNDERSPEED SHUTDOWN" or "ENGINE UNDERSPEED WARNING" will be displayed on the EMCP 3 display. The message is used to inform the operator of an under speed condition.

Note: The severity of the under speed condition will determine if a warning or shutdown event occurs.

The code for engine under speed is generated when the EMCP 3 determines that an engine under speed condition has occurred.

Test Step 1. TALK TO THE OPERATOR.

1. Determine the conditions that caused the under speed condition.

Expected Result:

An under speed was caused by an occurrence known to the operator and the operator would like to put the generator set back into service.

Results:

• OK - The operator can determine the cause for the under speed condition. The condition has been repaired and the operator wants to put the generator set back into service.

  Repair: Reset the generator set. Resume normal operation and verify that the problem has been corrected.

  STOP

• NOT OK - The under speed condition was not caused by an occurrence known to the operator. Proceed to Test Step 2.

Test Step 2. CHECK THE SETPOINTS.

1. View the "Engine Speed Monitor" and "Generator Desired Engine Speed Request" set points. Make a note of the set points. Refer to Testing and Adjusting, RENR7902, "Electronic Control Module (Generator Set) - Configure". Compare the set points against the default set points of the particular generator set.

Expected Result:

The set points are correct.

Results:

• OK - The set points are correct for your particular generator set. Proceed to test step 3 for EUI engines. Proceed to test step 4 for MUI engines.

• NOT OK - The set points are NOT correct.

  Repair: Reprogram the set points. Reset the generator set. Resume normal operation and verify that the problem has been corrected.

  STOP

Test Step 3. VERIFY ENGINE SPEED CAN BE VIEWED AND ADJUSTED FROM THE EMCP 3. (EUI ENGINES ONLY)

Verify that the engine speed can be viewed and adjusted from the EMCP 3 display.

Expected Result:

The engine speed can be viewed and adjusted from the EMCP 3 display.

Results:

• OK - The engine speed can be viewed and adjusted from the EMCP 3 display.

  Repair: Adjust the engine speed to meet site requirements. Resume normal operation and verify that the problem has been corrected.

  STOP

• NOT OK - The engine speed cannot be adjusted. Proceed to test step 7.

• NOT OK - The engine speed reads zero on the EMCP 3 display.

  Repair: The engine speed sensor may have failed or must be adjusted. Refer to Testing And Adjusting, RENR7902, "Speed Sensor (Engine) - Adjust". If the problem remains, replace the engine speed sensor.

  STOP

Test Step 4. CHECK THE SYSTEM BY USING THE SPEED POTENTIOMETER. (MUI ENGINES ONLY)

1. With the engine running, adjust the speed of the engine by turning the speed potentiometer.

Expected Result:

The engine can be adjusted to the desired speed.

Results:

• OK - The engine speed can be adjusted.

  Repair: Adjust the engine speed to meet site requirements. Resume normal operation and verify that the problem has been corrected.

  STOP

• NOT OK - The engine speed cannot be adjusted with the speed potentiometer. Proceed to test step 5.

Test Step 5. CHECK THE RESISTANCE OF THE ENGINE SPEED POTENTIOMETER. (MUI ENGINES ONLY)

1. Shut down the engine.

2. Disconnect the speed potentiometer from the terminals "11" and "12" on the 2301A Governor.

3. At the speed potentiometer, measure the resistance of the speed potentiometer.

Expected Result:

The resistance should be adjustable between 0 and 100 ohms.

Results:

• OK - The resistance of the sensor is correct. Proceed to Test Step 6.

• NOT OK - The resistance of the speed potentiometer is not correct.

  Repair: Replace the speed potentiometer. Resume normal operation and verify that the problem has been corrected.

  STOP

Test Step 6. CHECK THE SPEED POTENTIOMETER HARNESS FOR A OPEN CIRCUIT. (MUI ENGINES ONLY)

1. Disconnect the speed potentiometer harness from the 2301A governor.

2. Check for an open circuit. Check the resistance from terminal "11" of the 2301A governor to the same wire number at the speed potentiometer. The resistance must be 5 ohms or less.

3. Check for an open circuit. Check the resistance from terminal "12" of the 2301A governor to the same wire number at the speed potentiometer. The resistance must be 5 ohms or less

Expected Result:

Measured resistance between terminal "11" of the 2301A governor to the same wire at the speed potentiometer connector, is 5 ohms or less.

Measured resistance between terminal "12" of the 2301A governor to the same wire at the speed potentiometer connector, is 5 ohms or less.

Results:

• OK - The harness functions properly.

  Repair: The EMCP 3 may have failed. A failed EMCP 3 is unlikely. Exit the procedure and perform the entire procedure again. If the problem remains, replace the EMCP 3. Refer to Testing And Adjusting, RENR7902, " Electronic Control Module (Generator Set) - Replace".

  STOP

• NOT OK - The harness wiring with the incorrect resistance measurement has failed.

  Repair: Replace the failed harness from the 2301A governor to the speed potentiometer or repair the failed harness from the 2301A governor to the speed potentiometer. Resume normal operation and verify that the problem has been corrected.

  STOP

Test Step 7. CHECK THE J1939 DATA LINK BETWEEN THE EMCP 3 AND THE ENGINE ECM. (EUI ENGINES ONLY)

Refer to the generator set electrical system schematic in the service manual. Check the data link wiring between the EMCP 3 and the engine ECM. For more information on troubleshooting the data link, refer to Troubleshooting, RENR7902, "Data Link Circuit Fault ".

Results:

• OK - The J1939 data link wiring is correct.

  Repair: The EMCP 3 may have failed. A failed EMCP 3 is unlikely. Exit the procedure and perform the entire procedure again. If the problem remains, replace the EMCP 3. Refer to Testing And Adjusting, RENR7902, " Electronic Control Module (Generator Set) - Replace".

  STOP

• NOT OK - The wiring is not correct.

  Repair: Repair the data link wiring or replace the data link wiring. Resume normal operation and verify that the problem has been corrected.

  STOP