C6.6 Generator Set Caterpillar

Use this procedure to troubleshoot any suspect faults with the injector solenoids.

Use this procedure for the following diagnostic codes:

• 1-5 Cylinder #1 Injector open circuit

• 1-6 Cylinder #1 Injector short

• 2-5 Cylinder #2 Injector open circuit

• 2-6 Cylinder #2 Injector short

• 3-5 Cylinder #3 Injector open circuit

• 3-6 Cylinder #3 Injector short

• 4-5 Cylinder #4 Injector open circuit

• 4-6 Cylinder #4 Injector short

• 5-5 Cylinder #5 Injector open circuit

• 5-6 Cylinder #5 Injector short

• 6-5 Cylinder #6 Injector open circuit

• 6-6 Cylinder #6 Injector short

Perform this procedure under conditions that are identical to the conditions that exist when the fault occurs. Typically, faults with the injector solenoid occur when the engine is warmed up and/or when the engine is under vibration (heavy loads).

These engines have Electronic Unit Injectors (EUI) that are mechanically actuated and electronically controlled. The Electronic Control Module (ECM) sends a 70 volt pulse to each injector solenoid. The pulse is sent at the correct time and at the correct duration for a given engine load and speed. The solenoid is mounted on top of the fuel injector body.

If an open is detected in the solenoid circuit, a diagnostic code is generated. The ECM continues to try to fire the injector. If a short is detected, a diagnostic code is generated. The ECM will disable the solenoid circuit. The ECM will periodically try to fire the injector. If the short circuit remains this sequence of events will be repeated until the fault is corrected.

"Injector Solenoid Test"

Use the "Injector Solenoid Test" on the electronic service tool to aid in diagnosing an open circuit or a short circuit diagnostic code while the engine is not running. The "Injector Solenoid Test" will send a signal to each solenoid. The electronic service tool will indicate the status of the solenoid as "OK", "Open", or "Short". Due to the use of a shared supply, a short circuit in the wire that is used as a supply for the injector solenoid will cause three cylinders to have diagnostic codes.

"Cylinder Cutout Test"

Use the "Cylinder Cutout Test" on the electronic service tool to diagnose a malfunctioning injector while the engine is running. All active diagnostic codes must be repaired before running the "Cylinder Cutout Test". When a good injector is cut out, the "Fuel Position" should change. The change in the fuel position is caused by the other injectors that are compensating for the cut out injector. If a malfunctioning injector is cut out, the "Fuel Position" will not change. The "Cylinder Cutout Test" is used to isolate the malfunctioning injector in order to avoid replacement of good injectors.

Illustration 1	g01336666
Typical example of the fuel injector

Illustration 2	g01810354
Schematic of the circuit for the injector solenoids

Illustration 3	g01237524
Typical example of a harness connector for a fuel injector

Illustration 4	g01237558
Typical example of the cylinder head connector

Illustration 5	g01805334
View of the pin locations on the P2connector for the injectors (6) Injector (Number 6 Return) (7) Injector (Number 5 Return) (8) Injector (Number 4 Return) (33) Injector (Number 3 Return) (34) Injector (Number 2 Return) (35) Injector (Number 1 Return) (57) Injector (Number 1) (58) Injector (Number 2) (59) Injector (Number 3) (62) Injector (Number 6) (63) Injector (Number 5) (64) Injector (Number 4)

Test Step 1. Inspect Electrical Connectors and Wiring

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Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Thoroughly inspect connector P2. Thoroughly inspect the connectors at the valve cover base. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with injector solenoids.

4. Check the screw for the ECM connector for the correct torque of 5.0 N·m (44 lb in).

5. Check the harness and wiring for abrasion and for pinch points from the injectors to the ECM.

Expected Result:

All connectors, pins, and sockets are completely coupled and/or inserted and the harness is free of corrosion, of abrasion and of pinch points.

Results:

• OK - The harness is OK. Proceed to Test Step 2.

• Not OK - There is a fault in the connectors and/or the harness.

  Repair: Repair the connectors or the harness and/or replace the connectors or the harness. Ensure that all of the seals are correctly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the fault.

  STOP

Test Step 2. Check for Logged Diagnostic Codes that are Related to the Injector Solenoids

1. Connect the electronic service tool to the diagnostic connector.

2. Turn the keyswitch to the ON position.

3. Check for logged diagnostic codes that are related to the injector solenoids on the electronic service tool.

Expected Result:

One or more diagnostic codes that are related to the injector solenoids have been logged:

• 1-5 Cylinder #1 Injector open circuit

• 1-6 Cylinder #1 Injector short

• 2-5 Cylinder #2 Injector open circuit

• 2-6 Cylinder #2 Injector short

• 3-5 Cylinder #3 Injector open circuit

• 3-6 Cylinder #3 Injector short

• 4-5 Cylinder #4 Injector open circuit

• 4-6 Cylinder #4 Injector short

• 5-5 Cylinder #5 Injector open circuit

• 5-6 Cylinder #5 Injector short

• 6-5 Cylinder #6 Injector open circuit

• 6-6 Cylinder #6 Injector short

Results:

• OK - One or more diagnostic codes have been logged. Proceed to Test Step 4.

• Not OK - No diagnostic codes have been logged. Proceed to Test Step 3.

Test Step 3. Check the Variation of the Injectors between Cylinders

1. Start the engine.

2. Allow the engine to warm up to normal operating temperature.

3. After the engine is warmed to operating temperature, access the "Cylinder Cutout Test" on the electronic service tool by accessing the following display screens in order:
   • "Diagnostics"

   • "Diagnostic Tests"

   • "Cylinder Cutout Test"

4. Select the start button at the bottom of the screen for the cylinder cutout test on the electronic service tool.

5. Select the "6 Cylinder Cutout Test".

6. Follow the instructions that are provided in the cylinder cutout test. The cylinder cutout tests are interactive so the procedure is guided to the finish.

   Note: The "Manual Cylinder Cutout Test" is also available. Access the manual test by selecting the "Change" button on the screen for the cylinder cutout test. The "6 Cylinder Cutout Test" is the recommended starting procedure. The automated tests run twice collecting data. The two sets of data are analyzed and an "OK" or "Not OK" result is displayed.

7. Check for active diagnostic codes and for logged diagnostic codes that are related to the injector solenoids.

Expected Result:

All cylinders indicate "OK" on the electronic service tool.

Results:

• OK - All cylinders indicate "OK".

  Repair: If the engine is misfiring or if the engine has low power, refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable" and Troubleshooting, "Low Power/Poor or No Response to Throttle".

  If a diagnostic code results from running the cylinder cutout test, proceed to Test Step 4.

• Not OK - One or more cylinders displayed "Not OK" during the test. Proceed to Test Step 4.

Test Step 4. Use the "Injector Solenoid Test"

1. Start the engine.

2. Allow the engine to warm up to the normal operating temperature.

3. Stop the engine.

4. Turn the keyswitch to the ON position.

5. Access the "Injector Solenoid Test" on the electronic service tool by accessing the following display screens in order:
   • "Diagnostics"

   • "Diagnostic Tests"

   • "Injector Solenoid Test"

6. Activate the test.

   Note: Do not confuse the "Injector Solenoid Test" with the "Cylinder Cutout Test". The "Cylinder Cutout Test" is used to shut off fuel to a specific cylinder while the engine is running. The "Injector Solenoid Test" is used to actuate the injector solenoids while the engine is not running. This allows the click of the injector solenoids to be heard while the engine is off in order to determine that the circuit is functioning correctly.

7. As each solenoid is energized by the ECM, an audible click can be heard at the valve cover.

8. Perform the "Injector Solenoid Test" at least two times.

Expected Result:

All cylinders indicate "OK".

Results:

• OK - There is not an electronic fault with the injectors at this time.

  Repair: If the "Cylinder Cutout Test" returned a "Not OK" for any injector, refer to Troubleshooting, "Engine Misfires, Runs Rough or Is Unstable".

  STOP

• Open - Note the cylinders that indicate "Open". Proceed to Test Step 5.

• Short - Note the cylinders that indicate "Short". Proceed to Test Step 8.

Test Step 5. Check the Harness between the ECM and the Valve Cover Base for an Open Circuit

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Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Disconnect the connectors from the valve cover base.

3. Turn the keyswitch to the ON position.

4. Fabricate a jumper wire 100 mm (4 inch) long with terminals on both ends of the wire.

5. Insert one end of the jumper wire into the supply terminal for the suspect injector. Insert the other end of the jumper wire into the return terminal for the suspect injector.

6. Perform the "Injector Solenoid Test" at least two times.

7. Repeat this test for each suspect injector. Stop the "Injector Solenoid Test" before handling the jumper wires.

Expected Result:

The electronic service tool displays "Short" for the cylinder with the jumper wire.

Results:

• OK - The harness between the ECM and the valve cover base is OK. Proceed to Test Step 6.

• Not OK - There is a fault between the ECM and the valve cover base. Proceed to Test Step 7.

Test Step 6. Check the Injector Harness Under the Valve Cover

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Remove the valve cover.

3. Disconnect the harness from the suspect injector. Disconnect the harness from the injectors that shares the same supply circuit as the suspect injector.

   Note: Injectors 1, 2, and 3 share a common injector driver circuit in the ECM. Injectors 4, 5, and 6 share a common injector driver circuit in the ECM. If three injectors that share a common supply indicate "Open", the open circuit is probably caused by a faulty ECM.

4. Thoroughly clean the terminals on three injectors and on the harness connectors.

5. Exchange the harness between two of the three injectors that share the common driver.

6. Turn the keyswitch to the ON position.

7. Perform the "Injector Solenoid Test" at least two times.

Expected Result:

Exchanging the harness between the two injectors caused the fault to move to the other injector.

Results:

• OK - There is a fault with the injector harness under the valve cover.

  Repair: Repair the injector harness or replace the injector harness under the valve cover.Verify that the repair eliminates the fault.

  STOP

• Not OK - The injector may be faulty.

  Repair: Replace the faulty injector.Restore the wiring to the correct injectors.Perform the "Injector Solenoid Test".Verify that the repair eliminates the fault.

  STOP

Test Step 7. Check the ECM for an Open Circuit

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Disconnect connector P2 from the ECM.

3. Remove the supply wire and the return wire for the suspect injector from connector P2. Install a jumper wire into connector P2 in order to provide a short between the supply and the return of the suspect injector.

4. Reinstall connector P2 to the ECM.

5. Turn the keyswitch to the ON position.

6. Perform the "Injector Solenoid Test" at least two times.

Expected Result:

The electronic service tool displays "Short" for the cylinder with the jumper wire.

Note: Shorting a shared supply will affect the status of three injectors. Ignore the status of the other injectors that are on the shared shared supply.

Results:

• OK - The ECM is OK.

  Repair: If three injectors that share a supply indicate "Open", the open circuit is probably caused by a faulty ECM. Repair the engine harness or replace the engine harness, as required.Verify that the repair eliminates the fault.

  STOP

• Not OK - There may be a fault with the ECM.

  Repair: Perform the following procedure:

  1. Remove the jumper wire from connector P2 and reinstall the injector wires.

  2. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  3. Contact the Technical Communicator.

     Note: This consultation can greatly reduce the repair time.

  4. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  5. Perform the "Injector Solenoid Test".

  6. If the fault is resolved with the test ECM, reconnect the suspect ECM.

  7. If the fault returns with the suspect ECM, replace the ECM.

  8. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 8. Check the Harness between the ECM and the Valve Cover Base for a Short Circuit

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Disconnect the connectors from the valve cover base.

3. Turn the keyswitch to the ON position.

4. Perform the "Injector Solenoid Test" at least two times.

Expected Result:

All cylinders indicate "Open".

Results:

• OK - All cylinders indicate "Open". Proceed to Test Step 10.

• Not OK - One or more cylinders indicate "Short". Note the cylinders that indicate "Short". Proceed to Test Step 9.

Test Step 9. Check the ECM for a Short Circuit

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Disconnect connector P2 from the ECM and check for evidence of moisture entry.

3. Turn the keyswitch to the ON position.

4. Perform the "Injector Solenoid Test" at least two times.

Expected Result:

All cylinders indicate "Open" when connector P2 is disconnected from the ECM.

Note: When the engine harness is disconnected, all of the diagnostic codes for supply voltage to the sensors will be active. This is normal. Clear all of these diagnostic codes after completing this test step.

Results:

• OK - The short circuit is in the engine harness.

  Repair: The fault is most likely in one of the wires to the injector. Inspect the connectors for moisture and for corrosion. Also, check the wire insulation for damage and for strands that are exposed.Repair the engine harness or replace the engine harness, as required. Clear all diagnostic codes after completing this test step.Verify that the repair eliminates the fault.

  STOP

• Not OK - There may be a fault with the ECM.

  Repair: Perform the following procedure:

  1. Make sure that the latest flash file for the application is installed in the ECM. Refer to Troubleshooting, "Flash Programming".

  2. Contact the Technical Communicator.

     Note: This consultation can greatly reduce the repair time.

  3. If the Technical Communicator recommends the use of a test ECM, install a test ECM. Refer to Troubleshooting, "Replacing the ECM".

  4. Perform the "Injector Solenoid Test".

  5. If the fault is resolved with the test ECM, reconnect the suspect ECM.

  6. If the fault returns with the suspect ECM, replace the ECM.

  7. Use the electronic service tool in order to clear all logged diagnostic codes and then verify that the repair eliminates the fault.

  STOP

Test Step 10. Check the Engine Harness Under the Valve Cover for a Short Circuit

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Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Remove the valve cover.

3. Disconnect each of the injectors that indicate a "Short" from the wiring harness. Ensure that each of the connectors from the disconnected injector harness does not touch any other components.

4. Turn the keyswitch to the ON position.

5. Perform the "Injector Solenoid Test" at least two times.

Expected Result:

All of the injectors that were disconnected indicate "Open".

Results:

• OK - All of the injectors that were disconnected indicate "Open".

  Repair: Leave the injector wires disconnected. The supply wire is not shorted to the engine.

  Proceed to Test Step 11.

• Not OK - One or more of the injectors that were disconnected indicate "Short".

  Repair: The fault is most likely in the supply to the injector. Inspect the connectors for moisture and for corrosion. Also, check the supply wire's insulation for damage and for strands that are exposed.Repair the injector harness or replace the injector harness under the valve cover.Verify that the repair eliminates the fault.

  STOP

Test Step 11. Check for a Short Circuit in the Return Wire

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Electrical shock hazard. The electronic unit injector system uses 67-73 volts.

1. Turn the keyswitch to the OFF position. A strong electrical shock hazard is present if the keyswitch is not turned OFF.

2. Disconnect the connector P2 from the ECM.

3. Locate the terminal for the supply of the faulty injector in the connector P2. Measure the resistance from the terminal to the engine ground stud.

Expected Result:

The resistance is greater than 10 Ohms.

Results:

• OK - The resistance is greater than 10 Ohms.

  Repair: Reconnect connector P2.Replace the faulty injector.Perform the "Injector Solenoid Test".Verify that the repair eliminates the fault.

  STOP

• Not OK - There is a short in the return line.

  Repair: Disconnect the connectors from the valve cover base.Measure the resistance of the return wire between connector P2 and the engine ground stud.If the resistance is less than 10 Ohms, the fault is in the return wire between the ECM and the valve cover base.If the resistance is greater than 10 Ohms, the fault is in the return wire under the valve cover.Repair the injector harness or replace the injector harness.Perform the "Injector Solenoid Test" in order to verify that the repair eliminates the fault.

  STOP