G3512E Generator Set Engine Caterpillar

Use this procedure to troubleshoot suspect problems with the circuit for the gas shutoff valve.

This procedure covers the following diagnostic codes:

• 17-5 Fuel Shutoff Valve : Current Below Normal

• 17-6 Fuel Shutoff Valve : Current Above Normal

• 17-12 Fuel Shutoff Valve : Failure

The Electronic Control Module (ECM) contains the logic and the outputs for control of starting the engine and stopping the engine. The logic for starting and for stopping is customer programmable. The logic responds to inputs from the following components: engine control, emergency stop switch, remote start switch, data link and other inputs.

To enable fuel flow to the engine, the gas shutoff valve (GSOV) must be energized. The GSOV may be controlled by the ECM or by the customer's equipment. Use this procedure to troubleshoot either configuration.

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.

The most likely causes of a diagnostic code are a poor electrical connection or a problem in a wiring harness. The next likely cause is a problem with the GSOV. The least likely cause is a problem with the ECM.

A 17-12 diagnostic code is activated after the following sequence of events:

• The engine is running.

• The ECM receives a signal for stopping the engine.

• The ECM removes power from the electrical circuit for the GSOV.

• The engine rpm does not drop to at least crank terminate rpm within the time that is specified by the "Engine Speed Drop Time" parameter.

When these events occur, the ECM assumes that the GSOV did not close. The ECM terminates the ignition. The ECM also activates a 17-12 diagnostic code. Unburned gas remains in the air inlet and exhaust system.

The following information describes the system's operation when the GSOV is controlled by the ECM:

The ECM output for the gas shutoff valve is called the "fuel control relay". This output is energize-to-run. The ECM provides +Battery voltage to this output when the logic determines that fuel is required for engine operation. The ECM removes the voltage from this output in order to stop the engine. The gas shutoff valve is de-energized. This stops the fuel flow.

There are several possible configurations for wiring the GSOV. Consider the following information:

• The circuit for the GSOV must be complete in order for the engine to crank.

• The circuit for the GSOV must remain complete in order for the engine to run.

• The GSOV can be connected anywhere in the circuit.

Some possible configurations are discussed in the following paragraphs.

The GSOV is controlled by the customer's equipment. In this case, the circuit for the engine's control system must be a complete path. The circuit must include a resistor. Otherwise, a diagnostic code will be activated and the engine will not start. Illustration 1 is an example of this type of installation.

Illustration 1	g01300262
The GSOV is controlled by the customer's equipment.

The GSOV is controlled by the engine's control system. The engine harness is used for the connection. The customer may supply an additional switch in the electrical circuit for the GSOV. If the customer does not provide an optional switch, the circuit must be closed. Refer to Illustration 2 for an example of this type of installation.

Illustration 2	g01300271
The GSOV is controlled by the engine's control system.

The GSOV is controlled by the engine's control system. The GSOV is connected to a harness that is provided by the customer. The customer may supply an additional switch in the electrical circuit for the GSOV. Refer to Illustration 3 for an example of this type of installation.

Illustration 3	g01300374
The GSOV is controlled by the engine's control system. The GSOV is connected via wiring that is provided by the customer.

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 the following connectors and the wiring harnesses for the connectors:

   • J2/P2 connectors

   • J6/P6 and J7/P7 connectors on the terminal box

   • Fuel control relay's electrical connector

   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 fuel control relay.
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      Illustration 4	g01054878
      Typical fuel control relay

   3. Check the harness and wiring for abrasion and for pinch points from the fuel control relay 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, when possible. Replace parts, if necessary.

  STOP

Test Step 2. Check for Diagnostic Codes

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

2. Establish communication between Cat ET and the ECM.

3. Wait for 30 seconds and check for an active 17-5 diagnostic code.

   If there is an active 17-5 diagnostic code, proceed to the “Results” for this Test Step. Otherwise, continue this procedure.

   Note: The 17-5 diagnostic code cannot be detected when the output for the fuel control relay is ON. The output is ON when the engine control is in the START mode and the engine speed is not zero.

4. Use Cat ET to check the logged diagnostic codes. If there is a 17-6 diagnostic code or a 17-12 diagnostic code, clear the code.

   Note: In order for the ECM to check for a 17-6 diagnostic code, the sequence for engine start-up must be initiated. In order for the ECM to check for a 17-12 diagnostic code, the engine must be shut down after the engine is running.

5. Attempt to start the engine. If the engine starts, set the engine control to the STOP mode after the engine reaches idle speed.

6. Use Cat ET in order to check for a logged 17-6 diagnostic code or a 17-12 diagnostic code again.

Expected Result:

When the engine control was in the STOP mode, there was no active 17-5 diagnostic code.

After the engine was cranked or the engine was stopped, there was no logged 17-6 or 17-12 diagnostic code.

Results:

• OK - No diagnostic codes were generated. The output for the fuel control relay seems to be OK at this time. The initial diagnostic code was probably caused by a poor electrical connection.

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

  STOP

• Not OK (17-5 diagnostic code) - A 17-5 diagnostic code was activated. This can be caused by an actual open circuit or by a short circuit to the +Battery side.

  Repair: Determine the engine's configuration.

  If the ECM is controlling the GSOV, proceed to Test Step 3. If the ECM is not controlling the GSOV, proceed to Test Step 9.

• Not OK (17-6 diagnostic code) - After the engine was cranked, a 17-6 diagnostic code was generated.

  Repair: Determine the engine's configuration.

  If the ECM is not controlling the GSOV, the wiring that is connected to terminal P2-11 has a short to ground. The short circuit could be inside the terminal box or in the engine's wiring harness. Repair the wiring, when possible. Replace parts, if necessary. STOP.

  If the ECM is controlling the GSOV, proceed to Test Step 7.

• Not OK (17-12 diagnostic code) - When the engine control was set to the STOP mode, the GSOV did not close. A 17-12 diagnostic code was generated. The ECM disabled the ignition in order to stop the engine.

  Repair: Perform the following procedure:

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  Unburned gas in the air inlet and exhaust system may ignite when the engine is started. Personal injury and/or property damage may result. Before starting an engine that may contain unburned gas, purge the unburned gas from the air inlet and exhaust system. Refer to the topic on purging unburned gas in the "Starting the Engine" section.

  1. If the GSOV is controlled by the customer's equipment, troubleshoot the customer's equipment and the GSOV. Determine the cause of the open GSOV. Make repairs, as required.

  2. If the GSOV is controlled by the ECM, replace the GSOV.

  STOP

Test Step 3. Check for a Short Circuit to the +Battery Side

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Gaseous fuel is present. Personal Injury or Death can result from an open flame or spark igniting the gaseous fuel causing an explosion and/or fire. Always use a gas detector to determine the presence of gaseous fuel when maintaining and servicing. Contact your local gas provider immediately for assistance in the event of a leak.

Note: Open sparks can be generated during this test.

1. Make sure that no combustible gas is present in the surrounding atmosphere.

2. Verify that the engine control is in the STOP mode.

3. Disconnect the connector from the fuel control relay. Then reconnect the connector. Listen for an audible click from the relay.

   If the ambient noise is too loud, touch the relay when the relay is reconnected in order to feel the vibration. The relay will vibrate when the relay is de-energized and energized.

Expected Result:

There is no audible click and/or vibration when the relay is disconnected and reconnected. The relay is not energized when the engine control is in the STOP mode.

Results:

• OK - There is no audible click and/or vibration when the relay is disconnected and connected. There is no short circuit to the +Battery side. There is an open circuit. Proceed to Test Step 5.

• Not OK - There is an audible click and/or vibration when the relay is disconnected and connected. The relay is receiving power when the engine control is in the STOP position. There is probably a short circuit to the +Battery side in a connector or in a wiring harness. Proceed to Test Step 4.

Test Step 4. Determine the Cause of the Energized Relay

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Gaseous fuel is present. Personal Injury or Death can result from an open flame or spark igniting the gaseous fuel causing an explosion and/or fire. Always use a gas detector to determine the presence of gaseous fuel when maintaining and servicing. Contact your local gas provider immediately for assistance in the event of a leak.

Note: Open sparks can be generated during this test.

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

2. Use a 151-6320 Wire Removal Tool to remove terminals P2-11 and P2-21.

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

4. Disconnect the connector from the fuel control relay. Then reconnect the connector. Listen for an audible click from the relay.

   If the ambient noise is too loud, touch the relay when the relay is reconnected in order to feel the vibration. The relay will vibrate when the relay is de-energized and energized.

Expected Result:

There is no audible click and/or vibration when the relay is disconnected and reconnected. The relay is not energized when the wiring is removed from the P2 connector.

Results:

• OK - There is no audible click and/or vibration when the solenoid is disconnected and reconnected. The solenoid is not energized when the wiring is removed from the P2 connector.

  Repair: Use the following procedure to determine whether the circuit driver for the relay is faulty:

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

  2. Reinstall terminals P2-11 and P2-21. Pull on the wires in order to verify proper installation of the terminals.

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

  4. Disconnect the connector from the fuel control relay. Then reconnect the connector. Listen for an audible click from the relay.

     If the ambient noise is too loud, touch the relay when the relay is reconnected in order to feel the vibration. The relay will vibrate when the relay is de-energized and energized.

     If the relay is not energized, there is an intermittent problem with a connector and/or the wiring. Refer to Troubleshooting, "Electrical Connectors - Inspect".

     If the relay is energized, there may be a problem with the ECM.

     It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the problem is not resolved, perform the following steps:

     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".

  STOP

• Not OK - There is an audible click and/or vibration when the relay is disconnected and reconnected. The relay is energized when the wiring is removed from the P2 connector. There is a short circuit to the +Battery side in a harness.

  Repair: Repair the connector and/or wiring, when possible. Replace parts, if necessary.

  STOP

Test Step 5. Create a Short Circuit in order to Check for an Open Circuit

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

2. Disconnect the fuel control relay's connector.
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   Illustration 5	g01054883
   Typical fuel control relay (1) Connector for the fuel control relay (2) Jumper wire

3. Install a jumper wire (2) into the two terminals of the relay's connector (1) on the engine harness.

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

   Note: The 17-5 diagnostic code can only be detected when the output for the fuel control relay is OFF. The output is OFF when the engine control is in the STOP mode and the engine is not running.

5. Wait for 30 seconds and use the "Active Diagnostic" screen of Cat ET to look for a 17-5 diagnostic code.

Expected Result:

A 17-5 was not generated when the jumper wire was installed.

Results:

• OK - A 17-5 diagnostic code was not generated when the jumper wire was installed. The harness and the ECM are OK. There is a problem with the relay.

  Repair: Perform the following procedure:

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

  2. Remove the jumper wire from the relay's connector on the engine harness.

  3. Inspect the relay's connectors for damage, for moisture, and for corrosion. Make repairs, as needed.
  If the problem is not resolved, replace the fuel control relay.

  STOP

• Not OK - A 17-5 diagnostic code was generated when the jumper wire was installed. There may be an open circuit in the engine harness. Proceed to Test Step 6.

Test Step 6. Check the ECM

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

2. Use a 151-6320 Wire Removal Tool to remove terminals P2-11 and P2-21.
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   Illustration 6	g02014216
   (3) P2 connector

3. Install a jumper wire into terminals P2-11 and P2-21. Pull on the jumper wire in order to verify proper installation.

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

   Note: The 17-5 diagnostic code can only be detected when the output for the fuel control relay is OFF. The output is OFF when the engine control is in the STOP mode and the engine is not running.

5. Wait for 30 seconds and use Cat ET to check for an active 17-5 diagnostic code.

Expected Result:

There is no active 17-5 diagnostic code.

Results:

• OK - When the jumper wire was installed, there was no active 17-5 diagnostic code. The ECM detects the jumper wire at the P2 connector. However, the ECM did not detect the jumper wire at the connector for the fuel control relay. There is an open circuit between the P2 connector and the connector for the fuel control relay.

  Repair: Perform the following procedure:

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

  2. Use a 151-6320 Wire Removal Tool to remove the jumper wire from the P2 connector.

  3. Reinstall the terminals into P2-11 and P2-21. Pull on the wires in order to verify proper installation of the terminals.

  4. Thoroughly inspect the wiring between the P2 connector and the fuel control relay. Make repairs, when possible. Replace parts, if necessary.

  STOP

• Not OK - When the jumper wire was installed, a 17-5 diagnostic code was activated. The ECM did not detect the jumper wire in the J2 connector. There is a problem with the ECM.

  Repair: Perform the following procedure:

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

  2. Use a 151-6320 Wire Removal Tool to remove the jumper wire from the P2 connector.

  3. Reinstall the terminals into P2-11 and P2-21. Pull on the wires in order to verify proper installation of the terminals.

  4. Replace the ECM according to Troubleshooting, "ECM - Replace". Verify that the problem is resolved.

  STOP

Test Step 7. Create an Open Circuit in order to Check for a Short Circuit to Ground

1. Set the engine control to the OFF/RESET mode.

2. Disconnect the connector from the fuel control relay.

3. Set the engine control to the STOP mode.

4. Use Cat ET to clear the logged 17-6 diagnostic code.

5. To prevent the engine from starting, shut OFF the main gas supply.

   Note: To provide the output for the fuel control relay, the sequence for engine start-up must be initiated. Otherwise, a 17-6 diagnostic code cannot be generated.

6. Set the engine control to the START mode for at least 30 seconds. Then set the engine control to the STOP mode.

7. Use Cat ET to look for a logged 17-6 diagnostic code again.

Expected Result:

A 17-6 was not generated.

Results:

• OK - When the relay was connected, a 17-6 diagnostic code was generated. When the relay was disconnected, no 17-6 diagnostic code was generated. There is a problem with the relay.

  Repair: Perform the following procedure:

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

  2. Inspect the relay's connectors for damage and/or for corrosion. Make repairs, as needed.
  If the problem is not resolved, replace the relay.

  STOP

• Not OK - A 17-6 diagnostic code was generated when the relay was disconnected. There is a problem with the wiring or with the ECM. Proceed to Test Step 8.

Test Step 8. Check the ECM

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

2. Use the 151-6320 Wire Removal Tool to remove terminal P2-11.

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

4. Use Cat ET to clear the logged 17-6 diagnostic code.

5. To prevent the engine from starting, shut OFF the main gas supply.

   Note: To provide the output for the fuel control relay, the sequence for engine start-up must be initiated. Otherwise, a 17-6 diagnostic code cannot be generated.

6. Set the engine control to the START mode for at least 30 seconds. Then set the engine control to the STOP mode.

7. Use Cat ET to look for a logged 17-6 diagnostic code again.

Expected Result:

The 17-6 diagnostic code was not generated.

Results:

• OK - When the output to the relay was disconnected from the P2 connector, the 17-6 diagnostic code was not generated. However, a 17-6 diagnostic code was generated when the connector was disconnected from the fuel control relay. There is a problem in the wiring between the P2 connector and the connector for the fuel control relay.

  Repair: Perform the following procedure:

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

  2. Reinstall the terminal that was removed from P2-11. Pull on the wire in order to verify proper installation of the terminal.

  3. Repair the harness, when possible. Replace parts, if necessary.

  STOP

• Not OK - A 17-6 diagnostic code was generated when the output to the relay was disconnected from the P2 connector. There may be a problem with the ECM.

  Repair: Perform the following procedure:

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

  2. Reinstall the terminal that was removed from P2-11. Pull on the wire in order to verify proper installation of the terminal.

  3. It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the problem is not resolved, perform the following steps:

     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".

  STOP

Test Step 9. Identify the Cause of the 17-5 Diagnostic Code

1. Verify that the engine control is in the STOP mode.

2. Install two 7X-1710 Multimeter Probes into the P2 connector. Install the first probe into terminal P2-11. Install the second probe into terminal P2-21.

3. Connect a voltmeter to the probes. The polarity of the connections is not important. Measure the DC voltage on the terminals.

Expected Result:

The DC voltage on the terminals is approximately zero.

Results:

• OK - The DC voltage is approximately zero. The wiring that is connected to P2-11 does not have a short circuit to a positive voltage source. The wiring has an open circuit.

  Repair: The open circuit could be in the terminal box or in the engine's wiring harness. The open circuit may be in a connector. Repair the wiring, when possible. Replace parts, if necessary.

  STOP

• Not OK - The DC voltage is not approximately zero. The wiring that is connected to P2-11 has a short circuit to a positive voltage.

  Repair: The short circuit could be in the terminal box or in the engine's wiring harness. The short circuit may be in a connector. Repair the wiring, when possible. Replace parts, if necessary.

  STOP