G3516C, G3516E, and G3512E Generator Set Engines Caterpillar

Use this procedure in order to troubleshoot suspect problems with the circuit for the throttle actuator.

This procedure covers the following diagnostic codes:

• 1440-9 Throttle Actuator : Abnormal Update Rate

• 1440-11 Throttle Actuator invalid

• 1440-12 Throttle Actuator : Failure

The throttle actuator is an electronic actuator that works with the Electronic Control Module (ECM) in order to ensure the correct throttle position in all conditions of engine operation.

The ECM and the throttle actuator communicate via the CAN data link. The ECM sends a command signal to the actuator. The actuator sends the following information to the ECM: actuator position, CCM heartbeat, software version and internal fault diagnosis.

If the ECM cannot communicate with the throttle actuator, the ECM activates a 1440-9 diagnostic code and the engine is shut down. A 1440-9 diagnostic code is probably caused by a problem with an electrical connector or a harness. The next likely cause is a problem with the actuator. The least likely cause is a problem with the ECM.

Terminating resistors must be connected to each end of the CAN data link. The terminating resistors improve the communication between the devices. If there is an intermittent diagnostic code for any of the devices that are connected to the CAN data link, be sure to check the terminating resistor that is inside the terminal box. Also check the jumper wire that is connected between terminals "J" and "K" on the actuator for the bypass valve. Make repairs, when possible. Replace parts, if necessary.

Logged diagnostic codes provide a historical record. Before you begin this procedure, use Caterpillar Electronic Technician (ET) to print the logged codes to a file.

This troubleshooting procedure may generate additional diagnostic codes. Keep your mind on correcting the cause of the original diagnostic code. Clear the diagnostic codes after the problem is resolved.

Illustration 1	g01325969
Schematic for the circuit of the throttle actuator

Test Step 1. Inspect the Electrical Connectors and Wiring

1. Remove the electrical power from the engine.

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

2. Thoroughly inspect each of the following connectors:

   • J1/P1 connectors

   • J9/P9 connectors

   • Connectors on the throttle actuator

   1. Check the torque of the allen head screw for the ECM connectors.

   2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the throttle actuator.
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      Illustration 2	g01065718
      Right side view with the throttle actuator

   3. Check the wiring for abrasion and for pinch points from the throttle actuator to the ECM.

Expected Result:

All of the 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. Ensure that all of the seals are properly installed. Ensure that the connectors are properly engaged. Verify that the repair has eliminated the original problem.

  STOP

Test Step 2. Check for Diagnostic Codes

1. Connect Cat ET to the service tool connector on the terminal box.

2. Switch the 35 amp circuit breaker ON. Set the engine control to the STOP mode.

3. Use Cat ET in order to determine if one of the following diagnostic codes is active:

   • 1440-9 Throttle Actuator : Abnormal Update Rate

   • 1440-11 Throttle Actuator invalid

   • 1440-12 Throttle Actuator : Failure

Expected Result:

None of the diagnostic codes are active.

Results:

• OK - None of the diagnostic codes are active. The communication between the ECM and the throttle actuator appears to be OK at this time. However, diagnostic codes may be logged.

  Repair: If you are troubleshooting an intermittent problem, refer to Troubleshooting, "Electrical Connectors - Inspect".

  Terminating resistors must be connected to each end of the CAN data link. The terminating resistors improve the communication between the devices. If there is an intermittent diagnostic code for any of the devices that are connected to the CAN data link, be sure to check the terminating resistor that is inside the terminal box. Also check the jumper wire that is connected between terminals "J" and "K" on the actuator for the bypass valve. Make repairs, when possible. Replace parts, if necessary.

  STOP

• Not OK (Active 1440-9) - The ECM has detected a problem with the communication between the ECM and the throttle actuator. Proceed to Test Step 3.

• Not OK (Active 1440-11) - There is an active 1440-11 diagnostic code. This code indicates a problem with the linkage of the throttle actuator.

  Repair: Set the engine control to the OFF/RESET position. Remove the electrical power from the engine. Move the throttle plate through the entire range of travel while you feel the motion. If the motion is sticky and/or rough, investigate the cause of the binding. Perform the necessary repairs.

  STOP

• Not OK (Active 1440-12) - There is an active 1440-12 diagnostic code.

  Repair: The controller for the throttle actuator has detected an internal fault. Replace the actuator. Verify that the repair has eliminated the original problem.

  STOP

Test Step 3. Check for Electrical Power at the Actuator

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Illustration 3	g01234707
Locations for the voltage check at the junction box

1. Refer to Illustration 3. Measure the battery voltage at the junction box.

2. Disconnect the electrical connector from the actuator.
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   Illustration 4	g01233703
   Locations for the voltage check at the harness connector

3. Measure the voltage between terminals "N" and "P" at the harness connector.

Expected Result:

The voltage at the harness connector is within two volts of the voltage at the junction box.

Results:

• Yes - The voltage at the harness connector is within two volts of the voltage at the junction box. The actuator is receiving the proper operating voltage. Proceed to Test Step 4.

• No - The voltage at the harness connector is not within two volts of the voltage at the junction box. The actuator is not receiving the proper operating voltage.

  Repair: Determine the cause of the excessive voltage drop. Make the necessary repairs.

  STOP

Test Step 4. Check the CAN Data Link for Continuity Between the Throttle Actuator and the ECM

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

2. Disconnect the P1 connector. Disconnect the connector for the throttle actuator.

3. Use a multimeter to check for continuity between the points that are listed in Table 1. During each measurement, wiggle the harnesses in order to check for an intermittent problem with the harness. Be sure to wiggle the harness near each of the connectors. Be sure to wiggle the harness near the fuel metering valve.
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   Table 1

   Points to Check for Continuity
   Connector and Terminal	Harness Connector for the Throttle Actuator
   P1-34	Terminal B (CAN data link −)
   P1-50	Terminal A (CAN data link +)
   P1-42	Terminal M (CAN shield)

Expected Result:

The continuity of the circuits between the terminals is good.

Results:

• OK - The continuity of the circuits between the terminals is good. Proceed to Test Step 5.

• Not OK - At least one of the continuity checks indicates an open circuit. There is an open circuit for the CAN data link between the throttle actuator and the ECM.

  Repair: The open circuit could be caused by a poor electrical connection in a connector. Alternatively, the open circuit could be caused by one of the following components:

  • The harness inside the terminal box

  • The harness between the terminal box and the fuel metering valve

  • The harness between the fuel metering valve and the throttle actuator

  • The fuel metering valve
  Make repairs, when possible. Replace parts, if necessary.

  STOP

Test Step 5. Check the CAN Data Link 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. Use a multimeter to check for continuity between the points that are listed in Table 2. During each measurement, wiggle the harnesses in order to check for an intermittent problem with the harness. Be sure to wiggle the harness near each of the connectors. Be sure to wiggle the harness near the fuel metering valve.
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   Table 2

   Points to Check for Continuity
   Connector and Terminal	Connector and Terminal
   P1-34 (CAN data link −)	P1-50 (CAN data link +) P1-42 (CAN shield) P1-52 (+Battery) Ground strap for the ECM
   P1-50 (CAN data link +)	P1-42 (CAN shield) P1-52 (+Battery) Ground strap for the ECM
   P1-42 (CAN shield)	P1-52 (+Battery) Ground strap for the ECM

Expected Result:

All of the measurements indicate an open circuit.

Results:

• OK - All of the measurements indicate an open circuit. The CAN data link does not have a short circuit.

  Repair: Connect the P1 connector. Connect the connector for the throttle actuator.

  Proceed to Test Step 6.

• Not OK - At least one of the measurements indicate a short circuit.

  Repair: The short circuit could be caused by a poor electrical connection in a connector. Alternatively, the short circuit could be caused by one of the following components:

  • The harness inside the terminal box

  • The harness between the terminal box and the fuel metering valve

  • The harness between the fuel metering valve and the throttle actuator

  • The fuel metering valve
  Make repairs, when possible. Replace parts, if necessary.

  STOP

Test Step 6. Check for Diagnostic Codes

1. Switch the 35 amp circuit breaker ON. Set the engine control to the STOP mode.

2. Use Cat ET in order to determine if a 1440-9 diagnostic code is active.

Expected Result:

The 1440-9 code is not active.

Results:

• OK - The 1440-9 code is not active. The problem seems to be resolved. The initial diagnostic code was probably caused by a poor electrical connection.

  Repair: If there is an intermittent problem that is causing the code to be logged, refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP

• Not OK - The 1440-9 code is active.

  Repair: The active 1440-9 code could be caused by one of the following components:

  • The ECM

  • The throttle actuator

  • The actuator for the bypass valve

  • The fuel metering valve
  It is unlikely that any of the components that are listed above have failed. Exit this procedure and perform this procedure again. If the 1440-9 code remains active, perform the following procedure:

  1. Temporarily install a new ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is resolved with the new ECM, 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 original ECM. Refer to Troubleshooting, "ECM - Replace". If the problem is not resolved with a new ECM, install the original ECM. Continue with this procedure.

  2. Temporarily install a new throttle actuator. If the new throttle actuator operates correctly, the problem is resolved. If the new throttle actuator does not operate correctly, install the original throttle actuator and continue with this procedure.

  3. Temporarily install a new actuator for the bypass valve. If the new actuator for the bypass valve operates correctly, the problem is resolved. If the new actuator for the bypass valve does not operate correctly, install the original actuator for the bypass valve and continue with this procedure.

  4. Temporarily install a new fuel metering valve. If the new fuel metering valve operates correctly, the problem is resolved. If the new fuel metering valve does not operate correctly, install the original fuel metering valve. Refer to Troubleshooting, "Electrical Connectors - Inspect".

  STOP