Use this procedure to troubleshoot the electrical system if a problem is suspected with the circuit for the fuel control solenoid. Also, use this procedure if one of the diagnostic codes in Table 1 is active or easily repeated.
| Diagnostic Codes Table | ||
|---|---|---|
| Description | Conditions which Generate this Code | System Response |
| 17-5 Fuel Shutoff Valve : Current Below Normal | The Electronic Control Module (ECM) detects a low current in the circuit for the fuel control valve for 5 seconds. The output driver must be off for 5 seconds in order for this code to become active. |
The code is logged. The alarm output is activated. |
| 17-6 Fuel Shutoff Valve : Current Above Normal | With the output driver on 5 seconds, the ECM detected a high current in the circuit for the fuel control valve for one second. | The code is logged. The alarm output is activated. The output driver automatically resets and the output driver continues to try to activate the circuit component. |
| 17-12 Fuel Shutoff Valve : Failure | The Engine Control Switch (ECS) is placed in the STOP position. The ECM has shut off the fuel to the engine, but the engine rpm does not drop at the expected rate. The deceleration rate must be within rpm of the programmed "Engine Speed Drop Time". | The code is logged. The alarm output is activated. The power to the fuel control solenoid remains in the de-energized state and the ECM removes ignition power from the engine. |
The ECM contains the logic and the outputs for control of starting the engine and stopping the engine. Some of the logic for starting the engine and for stopping the engine is customer programmable. The logic responds to inputs from the following components: engine control switch, emergency stop switch, remote start switch, data link and other inputs.
The ECM outputs a signal to the fuel control solenoid in order to control the fuel shutoff valve. To enable gas flow to the engine, the fuel control solenoid must be energized. The fuel control solenoid may be controlled by the ECM or by the customer equipment. Use this procedure to troubleshoot either configuration.
The most likely cause of a diagnostic code is a poor electrical connection or a problem in a wiring harness. The next likely cause may be a problem with the fuel control solenoid. The least likely cause is a problem with the ECM.
When the 17-12 Fuel Shutoff Valve failure occurs, the ECM assumes that the fuel shutoff valve did not close. The ECM terminates the ignition. If the fuel control solenoid does not respond to the command, unburned gas will remain in the inlet and exhaust system.
Note: Ensure that the unburned gas is purged from the exhaust before restarting the engine. Failure to purge the unburned gas from the engine may result in an explosion in the exhaust piping.
The following information describes the systems operation when the GSOV is controlled by the ECM:
The ECM sends an output signal to the solenoid for the fuel control valve that controls the operation of the fuel control valve. This output is energize-to-run. During the crank cycle, when the engine speed exceeds 50 rpm, the ECM initiates a +Battery signal to the output for the fuel control valve. The solenoid becomes energized. As the valve opens, fuel begins to flow to the engine. The ECM removes the voltage from this output in order to stop the engine. The solenoid for the fuel control valve becomes de-energized. The fuel flow to the engine is stopped.
Four configurations are available for the wiring when the fuel shutoff valve is controlled by the ECM. Refer to Illustration 1. Each configuration must be wired in the configuration of a series circuit that includes the fuel control solenoid. The customer may install an additional emergency stop button anywhere in the circuit. The customer shutdown switch must have a normally closed contact and the switch must be wired in series with the fuel control solenoid.
The following information describes the system operation when the fuel shutoff valve is controlled by the customer equipment:
If the engine is controlled by the customer equipment, the ECM circuit must be wired in series with a resistor of 470 Ohms. Remove the harness connector and make the connection for the resistor directly to the wiring of the control harness. Refer to Illustration 2.
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| Illustration 1 | g01582793 |
Schematic of the configurations for fuel control by the ECM | |
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| Illustration 2 | g01582893 |
Schematic of the configurations for the fuel control by the customer equipment | |
Test Step 1. Inspect the Electrical Connectors and the Wiring
- Set the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
- Thoroughly inspect connectors (1) , (2) , (3) , and (5) . Also, check the condition of the connectors for emergency stop switch (4) and fuel control solenoid (6) that is for fuel shutoff valve (7) . Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
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| Illustration 3 | g01415665 |
Location of the connectors at the terminal box of the master ECM that are for control of the fuel shutoff valve (left front engine view) (1) J2/P2 ECM connectors for the master ECM (2) J5/P5 customer connectors (3) J8/P8 control harness connectors for the fuel control solenoid (4) Emergency stop switch (5) P10 connectors for the harness to the optional control panel | |
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| Illustration 4 | g01415696 |
Location of the components that are for control of the fuel shutoff valve (6) Fuel control solenoid (7) Fuel control valve | |
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the fuel control solenoid.
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| Illustration 5 | g01415749 |
Terminal locations at the P2 ECM connector that are associated with the fuel control solenoid (P2-11) Fuel control solenoid (P2-21) Return | |
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| Illustration 6 | g01415763 |
Terminal locations at the P5 customer connector that are associated with the fuel control solenoid (P5-60) Fuel control solenoid (P5-61) Return | |
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| Illustration 7 | g01415774 |
Terminal locations at the P8 control harness connector that are associated with the fuel control solenoid (P8-N) Fuel control solenoid (P8-X) Return | |
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| Illustration 8 | g01415806 |
Terminal locations at the emergency stop switch that is mounted on the terminal box that is for the master ECM (Terminal 1) Fuel control solenoid (Terminal 2) Return | |
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| Illustration 9 | g01415814 |
Terminal locations at the P10 connector for the optional control panel that are associated with the fuel control solenoid (P10-m) Fuel control solenoid (P10-t) Return | |
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| Illustration 10 | g01415822 |
Terminal locations at the connector for the fuel control solenoid (Terminal A) Fuel control solenoid (Terminal B) Return | |
- Check the allen head screw for each of the ECM connectors and for the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
- Check the wiring harnesses for abrasion, for corrosion and for pinch points.
Expected Result:
All connectors, pins, and sockets are coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion and of pinch points.
Results:
- OK - The harness and wiring appear to be OK. Proceed to Test Step 2.
- Not OK - There is a problem in the wiring harness.
Repair: Repair the connectors and/or the wiring. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are coupled. Verify that the problem is resolved.
STOP
Test Step 2. Check for Active Diagnostic Codes
- Turn the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
- Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
- Restore the electrical power to the engine. Set the engine control switch to the STOP position.
Note: The 17-5 Fuel Shutoff Valve : Current Below Normal can only be detected when the output for the start command is off. The output is normally off when the engine control switch is in the STOP position and the engine speed is zero rpm.
- Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. Check for an active 17-5 Fuel Shutoff Valve : Current Below Normal.
- Initiate an engine start-up.
Note: In order for the ECM to check for a 17-6 Fuel Shutoff Valve : Current Above Normal, the sequence for engine start-up must be initiated. In order for the ECM to check for a 17-12 Fuel Shutoff Valve : Failure, the engine must be shut down after the engine is running.
- Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. Check for 17-6 or 17-12 diagnostic codes that may be active.
- Attempt to start the engine. If the engine starts, set the engine control switch to the STOP position after the engine reaches idle speed.
- Again, use Cat ET to check for logged 17-6 and 17-12 codes.
Expected Result:
During the test procedure that is described above, no diagnostic codes for the fuel control solenoid were generated.
Results:
- OK - No diagnostic codes for the fuel control solenoid were generated.
Repair: The output for the fuel control solenoid appears to be OK at this time. The initial diagnostic code may have been caused by a poor electrical connection. If an intermittent problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
- Active 17-5 Code - A 17-5 diagnostic code was activated during the test. This code can be caused by an actual open circuit or by a short circuit to the +Battery. If the ECM is controlling the fuel shutoff valve, proceed to Test Step 3. If the ECM is not controlling the fuel shutoff valve, proceed to Test Step 9.
- Active 17-6 Code - After the engine was cranked, a 17-6 diagnostic code was generated.
Repair: Determine the configuration of the engine.If the ECM is not controlling the fuel shutoff valve, 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 wiring harness. Repair the wiring, when possible. Replace parts, if necessary. STOP.
If the ECM is controlling the fuel shutoff valve, proceed to Test Step 7.
- Active 17-12 Code - When the engine control switch was returned to the STOP position, the fuel shutoff valve did not close. A 17-12 diagnostic code was generated.
Repair: The ECM disabled the ignition in order to stop the engine. Perform the following procedure:
- If the fuel shutoff valve is controlled by a customer controller, troubleshoot the customer controller and the fuel shutoff valve. Determine the cause of the open fuel shutoff valve. Perform the necessary repairs.
Show/hide table
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.
- If the fuel shutoff valve is controlled by the ECM, the valve appears to be stuck open. Repair the fuel shutoff valve or replace the fuel shutoff valve. Verify that the repair eliminates the original problem.
STOP
Test Step 3. Check for a Short Circuit to the +Battery in the Harness
- Ensure that no combustible gas is present in the surrounding atmosphere.
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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. |
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Note: Open sparks can be generated during this test.
- Verify that the engine control switch is in the STOP position.
- Disconnect the connector from the fuel control solenoid.
- Use a multimeter to check the voltage at the harness connector for the fuel control solenoid.
Expected Result:
Voltage is not present at the harness connector that is for the fuel control solenoid while the engine control switch is in the STOP position.
Results:
- OK - Voltage is not present at the harness connector for the fuel control solenoid. There is no short circuit to the +Battery in the harness. There is an open circuit in the harness. There may be a problem with the ECM. Proceed to Test Step 4.
- Not OK - Voltage is present at the harness connector for the fuel control valve. The solenoid is receiving power when the ECS 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 6.
Test Step 4. Create a Short Circuit at the Harness Connector for the Fuel Control Solenoid
- Set the ECS to the OFF/RESET position. Remove the electrical power from the engine.
- Fabricate a jumper wire that is long enough to create a test circuit at the harness connector for the fuel control solenoid. Crimp connector pins to each end of the jumper wire.
- Disconnect the harness connector from the fuel control solenoid.
- Install the jumper wire into the two terminals of the harness connector for the fuel control solenoid.
- Restore the electrical power to the engine. Set the engine control switch to the STOP position.
Note: The 17-5 Fuel Shutoff Valve current below normal can only be detected when the output for the start command is off. The output is normally off when the engine control switch is in the STOP position and the engine speed is zero rpm.
- Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. Check for an active 17-5 Fuel Shutoff Valve : Current Below Normal.
- Attempt to start the engine. If the engine starts, set the ECS to the STOP position after the engine reaches idle speed.
Note: The 17-6 Engine Fuel Shutoff Valve #1 : Current Above Normal can only be detected when the output for the start command is on. The output is normally on when the ECS is switched from the STOP position to the START position. The output remains on during engine cranking.
- Turn the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
Restore the wiring to the original configuration.
Expected Result:
The 17-5 diagnostic code is no longer active and the 17-6 diagnostic code became active with the jumper wire installed.
Results:
- OK - The 17-5 diagnostic code is no longer active and the 17-6 diagnostic code became active.
Repair: The ECM detected the short circuit and did not activate the open circuit diagnostic code. The ECM and the harness are OK. There appears to be an open circuit in the windings of the solenoid for the fuel control valve. Perform the following procedure:
- Disconnect the harness connector for the solenoid.
- Use a multimeter to measure the coil resistance for the solenoid. Measure the resistance between terminals A and B at the solenoid connector.
- Restore the wiring to the original configuration.
STOP
- Not OK - A 17-5A 17-5 diagnostic code remains active with the jumper wire installed in the circuit. The ECM does not detect the short circuit. There is an open circuit in the wiring harness between the ECM and the fuel control valve. There may be a problem with the ECM. Proceed to Test Step 5.
Test Step 5. Create a Short Circuit at the ECM Connector and Check for Diagnostic Codes
- Verify that the ECS is in the OFF/RESET position and that the electrical power is removed from the engine.
- Disconnect the J2/P2 ECM connectors.
- Fabricate a jumper wire that is long enough to create a test circuit across the ECM connector. Crimp connector sockets to each end of the jumper wire.
- Remove the wires from terminal locations P2-11 and P2-21 at the P2 ECM connector. Install one end of the jumper wire into each of these terminal locations.
- Connect the J2/P2 ECM connectors.
- Restore the electrical power to the engine. Set the ECS to the STOP position.
Note: The 17-5 Engine Fuel Shutoff Valve #1 : Current Below Normal can only be detected when the output for the start command is off. The output is normally off when the ECS is in the STOP position and the engine speed is zero rpm.
- Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. Check for an active 17-5 Engine Fuel Shutoff Valve #1 : Current Below Normal.
- Attempt to start the engine. If the engine starts, set the ECS to the STOP position after the engine reaches idle speed.
Note: The 17-6 Engine Fuel Shutoff Valve #1 : Current Above Normal can only be detected when the output for the start command is on. The output is normally on when the ECS is switched from the STOP position to the START position. The output remains on during engine cranking.
- Turn the ECS to the OFF/RESET position. Remove the electrical power from the engine.
Expected Result:
The 17-5 diagnostic code is no longer active and the 17-6 diagnostic code became active with the jumper wire installed.
Results:
- OK - The 17-5 diagnostic code is no longer active and the 17-6 diagnostic code became active.
Repair: The ECM detects the jumper wire that is installed at the P2 ECM connector. There is an open circuit in the wiring harness between the ECM connector and the harness connector for the fuel control valve. The problem could be with one of the emergency stop switches. Check for proper operation of the switches. Perform the necessary repairs. Verify that the repair resolves the original problem.
STOP
- Not OK - A 17-5 diagnostic code remains active with the jumper wire installed at the ECM connector.
Repair: The ECM did not detect the short circuit. There appears to be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN).
STOP
Test Step 6. Check for a Short Circuit to the +Battery in the Harness Circuit at the ECM Connector
- Turn the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
- Disconnect the J2/P2 ECM connectors.
- At the P2 ECM connector, use a multimeter to check for a voltage on the harness between terminal locations P2-11 and P2-21.
- Restore the electrical power to the engine. Turn the ECS to the STOP position.
- With the ECS in the STOP position, use a multimeter to check for a voltage on the harness between terminal locations P2-25 and P2-32.
- Turn the ECS to the OFF/RESET position. Remove the electrical power from the engine.
- Connect the J2/P2 ECM connectors.
Expected Result:
Voltage is not present in the wiring harness circuit while the ECM connector is disconnected.
Results:
- OK - A voltage of 18 VDC to 28.5 VDC is not present in the wiring harness circuit while the ECM connector disconnected.
Repair: Voltage is present at the fuel control valve before isolating the harness from the ECM, but is not present after isolating the harness. There appears to be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN).
STOP
- Not OK - A voltage of 18 VDC to 28.5 VDC is not present in the harness circuit for the fuel control valve. There is a short to +Battery in the harness between the P2 ECM connector and the harness connector for the fuel control valve. Repair the harness, when possible. Replace parts, if necessary.
Repair:
STOP
Test Step 7. Create an Open Circuit at the Fuel Control Solenoid
- Turn the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
- Disconnect the harness connector from the fuel control solenoid.
- Restore the electrical power to the engine. Set the ECS to the STOP position.
Note: The 17-5 Engine Fuel Shutoff Valve #1 : Current Below Normal can only be detected when the output for the start command is off. The output is normally off when the ECS is in the STOP position and the engine speed is zero rpm.
- Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. Check for an active 17-5 Engine Fuel Shutoff Valve #1 : Current Below Normal.
- Attempt to start the engine. If the engine starts, set the ECS to the STOP position after the engine reaches idle speed.
Note: The 17-6 Engine Fuel Shutoff Valve #1 : Current Above Normal can only be detected when the output for the start command is on. The output is normally on when the ECS is switched from the STOP position to the START position. The output remains on during engine cranking.
Expected Result:
A 17-6 was not activated during the attempt to start the engine.
Results:
- OK - The 17-6 is no longer active when the harness connector is disconnected. The harness and ECM are operating correctly.
Repair: There appears to be a problem with the solenoid of the fuel control valve. Perform the following procedure:
- Disconnect the harness connector for the solenoid.
- Use a multimeter to measure the coil resistance of the solenoid. Check the resistance between terminals A and B at the connector for the solenoid.
- Restore the wiring to the original configuration.
STOP
- Not OK - A 17-6 diagnostic code was activated when the fuel control solenoid was disconnected. The fuel control solenoid is OK. The short circuit is in the harness or in a connector. There may be a problem with the ECM. Proceed to Test Step 8.
Test Step 8. Create an Open Circuit at the ECM Connector and Check for Diagnostic Codes
- Turn the ECS to the OFF/RESET position. Remove the electrical power from the engine.
- Use a wire removal tool to remove the wires from terminal locations P2-11 and P2-21 at the ECM connector.
- Restore the electrical power to the engine. Set the ECS to the STOP position.
Note: The 17-5 Engine Fuel Shutoff Valve #1 : Current Below Normal can only be detected when the output for the start command is off. The output is normally off when the ECS is in the STOP position and the engine speed is zero rpm.
- Monitor the active diagnostic code and the logged diagnostic codes on Cat ET. Wait at least 30 seconds in order for diagnostic codes to become active. Check for an active 17-5 Engine Fuel Shutoff Valve #1 : Current Below Normal.
- Attempt to start the engine. If the engine starts, set the ECS to the STOP position after the engine reaches idle speed.
Note: The 17-6 Engine Fuel Shutoff Valve #1 : Current Above Normal can only be detected when the output for the start command is on. The output is normally on when the ECS is switched from the STOP position to the START position. The output remains on during engine cranking.
- Turn the ECS to the OFF/RESET position. Remove the electrical power from the engine.
Expected Result:
The 17-6 diagnostic code is no longer active and the 17-5 diagnostic code became active with harness circuit isolated from the ECM.
Results:
- OK - The 17-6 diagnostic code is no longer active and the 17-5 diagnostic code became active
Repair: There is a problem with the wiring between the ECM connector and the harness connector that is for the fuel control valve. Perform the necessary repairs. Verify that the repair resolves the original problem.
STOP
- Not OK - With the harness circuit isolated from the ECM, the 17-6 diagnostic code remains active.
Repair: There appears to be a problem with the ECM. Before you consider replacing the ECM, consult with the Dealer Solutions Network (DSN).
STOP
Test Step 9. Check the ECM Circuit for an Open or a Short to the +Battery
- Turn the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
- Disconnect the J2/P2 ECM connectors.
- Restore the electrical power to the engine. Turn the engine control switch to the STOP position.
- Use a multimeter to check for a voltage between terminal P2-11 and engine ground. Check for a voltage between terminal P2-21 and engine ground
- Turn the engine control switch to the OFF/RESET position. Remove the electrical power from the engine.
- Restore the wiring to the original configuration.
Expected Result:
The voltage between terminals P2-11 and P2-21 is approximately zero.
Results:
- OK - The voltage between terminals P2-11 and P2-21 is approximately zero.
Repair: The wiring for the fuel control solenoid is not shorted to the +Battery. The wiring has an open circuit. The open circuit could be in the ECM junction box or in the engine wiring harness. The open circuit may be in a connector. Repair the wiring, when possible. Replace parts, if necessary. Verify that the repair eliminated the original problem.
STOP
- Not OK - The voltage between terminals P2-11 and P2-21 is not zero.
Repair: There is a short to the +Battery in the harness. The short circuit could be in the ECM junction box or in the engine wiring harness. The short circuit may be in a connector. Repair the wiring, when possible. Replace parts, if necessary. Verify that the repair eliminated the original problem.
STOP