G3516B Engines Caterpillar

The ECM monitors the generator output power in order to control the air/fuel ratio. The ECM uses a load signal from one of the following sources in order to monitor the generator output power:

• Electronic Modular Control Panel II+ (EMCP II+)

• Programmable Logic Controller (PLC)

• Wattmeter

The PLC and the wattmeter are also called power sensors.

Only one load signal is connected to the ECM. If the generator is equipped with the EMCP II+, the ECM receives the load signal from the Generator Set Control + (GSC+). The load signal is sent via the Cat Data Link. If the generator is not equipped with the EMCP II+, the ECM receives the load signal from a power sensor via terminal J1-25. The load signal from the power sensor is an analog voltage. The load signal increases from 0 VDC to 4.8 VDC as the generator output increases to the maximum output.

1719-03 Diagnostic Code

On powerup, the ECM will start requesting information on the generator load from the GSC+ via the Cat Data Link. If 2 seconds elapse and the ECM does not receive a response from the GSC+, the ECM looks for a signal on terminal J1-25. If there is no load signal on terminal J1-25, the ECM will generate a 1719-03 diagnostic code. If the engine is running, the engine will shut down.

A 1719-03 diagnostic code is also generated if the voltage on terminal J1-25 ever exceeds 4.8 VDC. If the engine is running, the engine will shut down.

1719-04 Diagnostic Code

This code only applies to engines that are equipped with a power sensor.

If the engine load is greater than 20 percent and the voltage on terminal J1-25 is less than 0.2 VDC, the ECM will generate a 1719-04 diagnostic code. If the engine is running, the engine will shut down.

1719-12 Diagnostic Code

This code only applies to engines that are equipped with the EMCP II+.

The ECM calculates two values that represent the engine load. One value is calculated by using the information on the generator load from the GSC+. The other value is calculated from the following inputs:

• The value of the "Fuel Quality" parameter

• Inlet air temperature and pressure

• Other factors

The ECM compares the two values. If the value that is calculated by using the information from the GSC+ is not within 20 percent of the other value, the ECM will generate a 1719-12 diagnostic code. If the engine is running, the engine will shut down.

Illustration 1	g02891079
Schematics of the inputs for the generator output power sensor Only one input is used. The input that is used depends on the generator configuration.

Test Step 1. Inspect the Electrical Connectors and Wiring

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Illustration 2	g01076153
Terminal box (1) J1/P1 connectors for the ECM (2) 16 amp circuit breaker (3) J9/P9 connectors for the wiring to the customer connections

1. Set the engine control to the OFF/RESET mode. Switch 16 amp circuit breaker (2) to the OFF position.

Note: For the following steps, refer to Troubleshooting, "Inspecting Electrical Connectors".

2. Thoroughly inspect the following components:
   • J1/P1 connectors

   • J9/P9 connectors on the terminal box

   • Wiring and the connections between the generator output power sensor and the ECM

   1. Check the torque of the allen head screw for the ECM connectors. The proper torque is 6 ± 1 N·m (55 ± 9 lb in).
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   Illustration 3	g02891458
   Harness side of the P1 connector (P1-8) Cat Data Link + (P1-9) Cat Data Link - (P1-25) Load signal

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   Illustration 4	g02891476
   Harness side of the P9 connector (P9-c) Cat Data Link - (P9-g) Cat Data Link + (P9-X) Load signal

   2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit for the generator output power sensor.

   3. Check the harness and wiring for abrasion and for pinch points between the generator output power sensor and the ECM.

Expected Result:

All connectors, pins, and sockets are connected properly. The connectors and the wiring do not have corrosion, abrasion, or pinch points.

Results:

• OK - The components are in good condition with proper connections. Proceed to Test Step 2.

• Not OK - The components are not in good condition and/or at least one connection is improper.

  Repair: Perform the necessary repairs and/or replace parts, if necessary.

  STOP

Test Step 2. Check for a Diagnostic Code

1. Connect the Cat Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".

2. Start the engine and run the engine. Attempt to apply at least a 30 percent load to the generator.

3. Observe the "Active Diagnostic" screen on Cat ET. Allow a minimum of 30 seconds for any codes to activate. Look for these codes:
   • 1719-03

   • 1719-04

   • 1719-12

4. Stop the engine.

Expected Result:

There are no active codes for the generator output power sensor.

Results:

• No active codes - There are no active codes for the generator output power sensor. There may be a logged code for the generator output power sensor.

  Repair: If there is a logged code for the generator output power sensor, there may be a problem with the wiring and/or a connector. Refer to Troubleshooting, "Inspecting Electrical Connectors".

  STOP

• Active 1719-03 code - There is an active 1719-03 code. If the generator is equipped with EMCP II+, proceed to Test Step 7. Otherwise, proceed to Test Step 5.

• Active 1719-04 code - There is an active 1719-04 code. Proceed to Test Step 3.

• Active 1719-12 code - There is an active 1719-12 code. Proceed to Test Step 9.

Test Step 3. Check the "Load Signal" Wiring for a Short Circuit

1. Disconnect the P1 connector from the ECM.

2. Disconnect the "load signal" wire from the power sensor.

3. Check for continuity between P1-25 and all the other terminals on the P1 connector.

Expected Result:

Each continuity check indicates an open circuit.

Results:

• OK - Each continuity check indicates an open circuit. The "load signal" wiring does not have a short circuit. Proceed to Test Step 4.

• Not OK - At least one continuity check indicates a short circuit.

  Repair: The problem may be between the P1 connector and the J9 connector. Alternatively, the problem may be between the P9 connector and the power sensor.Repair the harness or the connection, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 4. Check the "Load Signal" Wiring for Continuity

Note: A potentiometer may be installed in the "load signal" wiring. A high resistance reading may be caused by the potentiometer.

1. Check the continuity of the wire between P1-25 and the power sensor.

Expected Result:

The "load signal" wiring has continuity.

Results:

• OK - The "load signal" wiring has continuity. Reconnect the P1 connector. Reconnect the "load signal" wires to the power sensor. Be sure to observe the correct polarity. Proceed to Test Step 6.

• Not OK - The "load signal" wiring has an open circuit. The open circuit may be in a wire, in a connector, or in the potentiometer.

  Repair: Repair the component, when possible. Replace parts, if necessary. Verify that the original problem is resolved.

  STOP

Test Step 5. Check the "Load Signal +" Wire for a Short Circuit

1. Verify that the engine control is in the OFF/RESET mode and that the 35 amp circuit breaker is OFF.

2. Disconnect the P1 connector from the ECM.

3. Disconnect the "load signal +" wire from the power sensor.

4. Check for continuity between P1-25 and all the other terminals on the P1 connector.

Expected Result:

Each continuity check indicates an open circuit.

Results:

• OK - Each continuity check indicates an open circuit. The "load signal +" wire does not have a short circuit.

  Repair: Reconnect the P1 connector. Reconnect the "load signal +" wire to the power sensor.

  Proceed to Test Step 6.

• Not OK - At least one continuity check indicates a short circuit. There is a short circuit in a harness or in a connector.

  Repair: The problem may be between the P1 connector and the J9 connector. Alternatively, the problem may be between the P9 connector and the generator output power sensor.Repair the harness or the connection, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

Test Step 6. Check the Power Sensor, the Potential Transformers, and the Current Transformers

Verify that the power sensor, the potential transformers, and the current transformers are operating correctly. Refer to the appropriate service literature for the components.

Expected Result:

The components are operating correctly.

Results:

• OK - The components are operating correctly. Proceed to Test Step 13.

• Not OK - At least one of the components is not operating correctly.

  Repair: Repair the component, when possible. Replace the component, if necessary. Verify that the original problem is resolved.

  STOP

Test Step 7. Check the Continuity of the Cat Data Link

1. Set the engine control to the OFF/RESET mode. Switch the 35 amp circuit breaker OFF.

2. Disconnect Cat ET from the service tool connector.

3. Disconnect the wiring for the Cat Data Link from the GSC+.

4. Disconnect the P1 connector from the ECM.

5. Measure the resistance between the points that are listed in Table 1. During each measurement, wiggle the wires in the harness in order to check for an intermittent problem. Be sure to wiggle the wires near each of the connectors.
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   Table 1

   Resistance Measurements for the Cat Data Link
   Connector and Terminal	Connector and Terminal
   P1-8	Terminal 19 on the GSC+
   P1-9	Terminal 20 on the GSC+
   P1-8	Ground strap for the ECM
   P1-9	Ground strap for the ECM

Expected Result:

Each check of the resistance between the terminals is less than five Ohms.

Each check of the resistance between a terminal and the ground strap is greater than 20,000 Ohms.

Results:

• OK - Each check of the resistance for the Cat Data Link is within the specification. The wiring for the Cat Data Link appears to be OK.

  Repair: Perform the following procedure:

  1. Reconnect the wiring to the GSC+. Be sure to connect each wire to the appropriate terminal.

  2. Reconnect the P1 connector.

  Proceed to Test Step 8.

• Not OK - At least one check of the resistance for the Cat Data Link is incorrect. There is a problem with the wiring for the Cat Data Link.

  Repair: Repair the connection and/or the wire, when possible. Replace parts, if necessary. Verify that the original problem is resolved.

  STOP

Test Step 8. Check the GSC+

Verify that the GSC+ is operating correctly. Refer to the appropriate service literature for the EMCP II+.

Expected Result:

The GSC+ is operating correctly.

Results:

• OK - The GSC+ is operating correctly. Proceed to Test Step 13.

• Not OK - The GSC+ is not operating correctly.

  Repair: Repair the GSC+. Refer to the appropriate service literature for the EMCP II+. Verify that the original problem is resolved.

  STOP

Test Step 9. Check the "Fuel Quality" parameter

Verify that the value of the "Fuel Quality" parameter is correct. Use the value that is obtained from the Caterpillar Software, LEKQ6378, "Methane Number Program".

Expected Result:

The value of the "Fuel Quality" parameter is correct.

Results:

• OK - The value of the "Fuel Quality" parameter is correct. Proceed to Test Step 10.

• Not OK - The value of the "Fuel Quality" parameter is not correct.

  Repair: Enter the correct value for the parameter. Verify that the original problem is resolved.

  STOP

Test Step 10. Check the Sensors for the Air Inlet Manifold

1. If the engine is running, stop the engine.

2. Connect a pressure gauge and a temperature sensor to the air inlet manifold.

3. View the Status Group 1 on Cat ET. Compare the values on the instruments with the following parameters:
   • "Inlet manifold air pressure (abs)"

   • "Inlet air temperature"

Expected Result:

The values of the parameters are correct.

Results:

• OK - The values of the parameters are correct. Proceed to Test Step 8.

• Not OK - One or both of the values of the parameters are incorrect.

  Repair: Replace the appropriate sensor. Verify that the original problem is resolved.

  STOP

Test Step 11. Check the GSC+

Verify that the GSC+ is operating correctly. Refer to the appropriate service literature for the EMCP II+.

Expected Result:

The GSC+ is operating correctly.

Results:

• OK - The GSC+ is operating correctly. Proceed to Test Step 12.

• Not OK - The GSC+ is not operating correctly.

  Repair: Repair the GSC+. Refer to the appropriate service literature for the EMCP II+. Verify that the original problem is resolved.

  STOP

Test Step 12. Verify that the Output Power Reading is Correct

Operate the generator at various loads. Verify that the value of the "Generator Real kW" parameter in Status Group 1 is within 1 percent of the generator output power.

Expected Result:

The value of the "Generator Real kW" parameter is correct.

Results:

• OK - The value of the "Generator Real kW" parameter is correct. Proceed to Test Step 13.

• Not OK - The value of the "Generator Real kW" parameter is incorrect.

  Repair: Refer to Troubleshooting, "Generator Output Power Readings Do Not Match".

  STOP

Test Step 13. Check the ECM

It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the problem is not resolved, temporarily install a new ECM. Refer to Troubleshooting, "Replacing the ECM".

Expected Result:

The problem is resolved when a new ECM is installed.

Results:

• OK - The problem is resolved when a new ECM is installed.

  Repair: Install the original ECM and verify that the problem returns. If the new ECM operates correctly and the original ECM does not operate correctly, replace the ECM. Before you replace the ECM, consult the ECM Hotline.

  STOP

• Not OK - The problem is not resolved when a new ECM is installed.

  Repair: Reinstall the original ECM. Consult with Caterpillar customer service for large gas engines.

  STOP