C-12 Generator Set Engine Caterpillar

• An injector solenoid may have a problem.

• You have been directed to this procedure from Troubleshooting, "Troubleshooting without a Diagnostic Code".

• There is an active diagnostic code for an injector solenoid.

Use this procedure for the following diagnostic codes:

• 1-11 Injector Cylinder #1 fault

• 2-11 Injector Cylinder #2 fault

• 3-11 Injector Cylinder #3 fault

• 4-11 Injector Cylinder #4 fault

• 5-11 Injector Cylinder #5 fault

• 6-11 Injector Cylinder #6 fault

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

These engines have Hydraulically Actuated Electronically Controlled Unit Injectors (HEUI). The Engine Control Module (ECM) sends a 105 volt pulse to each injector solenoid. The pulse is sent at the proper 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 problem is corrected.

When an injector is replaced, program the new injector code into the ECM. If the ECM is replaced, all six injector codes must be programmed into the new ECM. Refer to Troubleshooting, "Replacing the ECM" for the correct procedure.

The Caterpillar Electronic Technician (ET) includes the following tests that aid in troubleshooting the injector solenoids:

"Cylinder Cutout Test"

The "Cylinder Cutout Test" is used on an engine in order to determine the individual cylinder performance while the engine is running. As one or more cylinders are cut out during the test, the "Cylinder Cutout Test" uses the "Fuel Position" of each injector in order to evaluate the performance of the remaining cylinders that are firing. As the different cylinders are cut out, a comparison of the change in "Fuel Position" is used to identify cylinders that are weak or misfiring. One reason for a cylinder that is weak or misfiring is an injector that is malfunctioning mechanically.

During the test, when a good injector is cut out, the "Fuel Position" of the remaining injectors will show a consistent change. This consistent change in the "Fuel Position" is caused by the remaining injectors that are compensating for the cut out injector. If a malfunctioning injector is cut out, the "Fuel Position" will not show a proportional change. This unbalanced change is the result of the smaller quantity of fuel that is needed to compensate for the power loss from the malfunctioning injector. The "Cylinder Cutout Test" is used to isolate a malfunctioning injector in order to avoid replacement of injectors that are in good repair.

Note: Prior to running the "Cylinder Cutout Test", all active diagnostic codes must be repaired.

"Injector Solenoid Test"

Use the "Injector Solenoid Test" to aid in diagnosing an open circuit or a short circuit while the engine is not running. The "Injector Solenoid Test" briefly activates each solenoid. A good solenoid will create an audible click when the solenoid is activated. Cat ET will indicate the status of the solenoid as "OK", "Open", or "Short".

Note: Refer to Illustration 1. Two injector solenoids share a common return wire. For this reason, an open circuit or a short circuit in a return wire could cause diagnostic codes for two injector solenoids.

Illustration 1	g01198132
Schematic for the injector solenoids

Test Step 1. Inspect the Electrical Connectors and the Wiring

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM. A strong electrical shock hazard is present if electrical power is not removed from the ECM.

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Illustration 2	g01198129
Left side engine view (typical example) (1) Connector for the injector harness (2) J2/P2 ECM connectors

2. Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

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Illustration 3	g01129751
P2 terminals that are associated with the injector solenoids (P2-36) Injector 1 supply (P2-37) Injector 2 supply (P2-38) Injector 3 supply (P2-39) Injector 4 supply (P2-44) Injector 1 & 2 return (P2-45) Injector 3 & 4 return (P2-46) Injector 5 & 6 return (P2-54) Injector 5 supply (P2-55) Injector 6 supply

3. Perform a 45 N (10 lb) pull test on each of the wires in the J2/P2 ECM connector and in the connector for the injector harness that are associated with the circuit.

4. Check the allen head screw for each of the ECM connectors for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

5. Check the harness and wiring for abrasion and for pinch points from the injector valve cover base to the ECM.

Expected Result:

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

Results:

• OK - The wiring and the connectors appear to be OK. Proceed to Test Step 2.

• Not OK - There is a problem with the wiring and/or the connectors.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the repair eliminates the problem.

  STOP

Test Step 2. Check for Logged Diagnostic Codes

1. Connect Cat ET to the service tool connector.

2. Restore electrical power to the ECM.

3. Monitor the "Logged Diagnostic Code" screen on Cat ET.

4. Look for a 11 code that is related to one of the unit injectors.

Expected Result:

There is a 11 code that has been logged for one of the unit injectors.

Results:

• OK - There is a logged diagnostic code for one or more of the injectors. The ECM has detected an electrical problem. Proceed to Test Step 4.

• Not OK - There are no logged diagnostic codes for the injectors. There may be a malfunctioning cylinder that is caused by a mechanical problem. Proceed to Test Step 3 to check for a weak cylinder.

Test Step 3. Use the "Cylinder Cutout Test" to Check the Variation Between the Cylinders

1. Connect Cat ET to the service tool connector.

2. Start the engine.

3. Allow the engine to warm up to the normal operating temperature of 77 °C (171 °F).

4. After the engine is warmed to operating temperature, access the "Cylinder Cutout Test" on Cat ET.

5. Enable the cooling fan, if the fan is not controlled by the ECM. If the ECM controls the cooling fan, the cooling fan will start automatically when the test begins.

6. Shut off all parasitic loads which could affect the results of the test.

7. Run the "Cylinder Cutout Test".

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

   2. Print a report of the test and evaluate the results.

Expected Result:

The results of the "Cylinder Cutout Test" indicates that all of the cylinders are OK.

Results:

• OK - The "Cylinder Cutout Test" indicates that all of the cylinders are OK.

  Repair: The results of the test has indicated that all of the injectors appear to be operating correctly. If no diagnostic codes for the injectors are active or logged, suspect an electrical problem or a mechanical problem with another system on the engine.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".

  STOP

• Not OK - Cat ET indicates that there is a weak cylinder. There may be an injector solenoid that is partially shorted or there may be a mechanical problem with the cylinder. Proceed to Test Step 4.

Test Step 4. Use the "Injector Solenoid Test" to Test the Injector Solenoids

1. Start the engine.

2. Ensure that the engine has warmed to the normal operating temperature of 77 °C (171 °F).

3. Stop the engine.

4. Restore electrical power to the ECM. Do not start the engine.

5. Access the "Injector Solenoid Test" on Cat ET.

6. Activate the test.

   Note: Do not confuse the "Injector Solenoid Test" with the "Cylinder Cutout Test". The cylinder cutout test is used while the engine is running. The injector solenoid test is used in order to actuate the injector solenoids while the engine is stopped.

7. As each solenoid is energized by the ECM an audible click can be heard at the valve cover. Listen for a click at each valve cover. A black square will appear over the cylinder number on Cat ET as each cylinder is being fired.

8. Perform the injector solenoid test at least two times.

Expected Result:

Cat ET reports each cylinder as "OK", as "SHORT", or as "OPEN".

Results:

• "OK" - Cat ET reported that all cylinders are "OK".

  Repair: There is not an electronic problem with the injectors at this time. If an intermittent electrical problem is suspected, refer to Troubleshooting, "Electrical Connectors - Inspect" for the proper troubleshooting procedure.In the previous test step, if the "Cylinder Cutout Test" indicated a problem with one of cylinders, there may be a problem with the injector for the cylinder or there may be a mechanical problem with the cylinder.If a problem with an injector is suspected, replace the suspect injector with another injector on the engine in order to confirm the problem. Use the "Exchange" feature in the "Injector Trim Calibration" tool that is in Cat ET to exchange the information for the injector trim file. Perform the "Cylinder Cutout Test" again. If the problem moves to the other cylinder with the suspect injector, replace the injector. If the problem remains in the original cylinder, there is a mechanical problem with the cylinder.If a mechanical problem with the cylinder is suspected, refer to Systems Operation/Testing and Adjusting, "Compression - Test" in order to help isolate the problem.

  STOP

• SHORT - Cat ET reported that one or more cylinders are "SHORT". Record the cylinder numbers for the injectors that indicate "SHORT". Proceed to Test Step 5.

• OPEN - Cat ET reported that one or more cylinders are "OPEN". Record the cylinder numbers for the injectors that indicate "OPEN". Proceed to Test Step 6.

Test Step 5. Use the Injector Solenoid Test to Check for Shorts in the Engine Wiring Harness

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM. A strong electrical shock hazard is present if the electrical power is not removed from the ECM.

2. Disconnect the connector for the injector harness at the valve cover. Check for evidence of moisture entry. Refer to Troubleshooting, "Electrical Connectors - Inspect" for troubleshooting details.

3. Restore electrical power to the ECM.

4. Perform the injector solenoid test at least two times.

Expected Result:

All cylinders indicate "OPEN".

Results:

• OK - The status of all cylinders indicate "OPEN" when the connector for the injector harness is disconnected. There is not a short circuit in the engine harness from the ECM connector to the connector for the injector harness. Reconnect the connector for the injector harness. Proceed to Test Step 10.

• Not OK - At least one cylinder does not indicate "OPEN" when the connector for the injector harness is disconnected. Record the cylinder numbers that indicate a short circuit. Proceed to Test Step 7.

Test Step 6. Use the Injector Solenoid Test to Check for Opens in the Engine Wiring Harness

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM. A strong electrical shock hazard is present if the electrical power is not removed from the ECM.

2. Disconnect the connector for the injector harness.

3. Fabricate a jumper wire that is long enough to jumper two connector pins at the connector for the injector harness. Crimp connector sockets to each end of the jumper wire.

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Illustration 4	g01198133
Terminals at the connector for the injector harness that are associated with the injector solenoids (1) Injector 1 supply (2) Injector 2 supply (3) Injector 3 supply (4) Injector 4 supply (5) Injector 5 supply (6) Injector 6 supply (8) Injector 5 and 6 return (10) Injector 3 and 4 return (12) Injector 1 and 2 return

4. Insert one end of a jumper wire onto the pin of the supply wire of the suspect injector. Insert the other end of the jumper wire onto the pin of the return wire of the suspect injector. For example, if injector 5 is the problem injector, insert the jumper onto terminal 5 and into terminal 8 of the connector for the injector harness.

   Ensure that the ends of the jumper wire are not in contact with any of the other terminals in the connector.

5. Restore electrical power to the ECM.

6. Perform the injector solenoid test at least two times.

7. Remove electrical power from the ECM.

   Repeat this test for each suspect Injector. Ensure that the injector solenoid test is disabled before handling the jumper wires.

   Note: Cat ET may report a "SHORT" for the injector that shares the supply with the suspect injector. Disregard the result for this injector.

Expected Result:

Cat ET displays "SHORT" for the cylinder with the jumper wire.

Results:

• OK - Cat ET displays "SHORT" for the cylinder with the jumper wire. The ECM and the engine harness are OK. Remove the jumper wire. Reconnect the connector for the injector harness. Proceed to Test Step 9.

• Not OK - Cat ET displays "Open" for the cylinder with the jumper wire. The problem is in the engine harness or in the ECM. Proceed to Test Step 8.

Test Step 7. Use the Injector Solenoid Test to Check the ECM for Short Circuits

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM.

2. Disconnect the J2/P2 ECM connectors.

3. Remove the suspect injector's supply wire and return from the P2 ECM connector. Connect the J2/P2 ECM connectors.

4. Restore electrical power to the ECM.

5. Perform the injector solenoid test at least two times. Record the results.

   Note: Cat ET will report a "OPEN" for the injector that shares the supply with the suspect injector. Disregard the result for this injector.

Expected Result:

Cat ET indicates "OPEN" for the suspect cylinder.

Results:

• OK - Cat ET indicates "OPEN" for the suspect cylinder.

  Repair: The short circuit is in the engine harness. Repair the engine harness or replace the engine harness, as required. Verify that the repair eliminates the problem.

  STOP

• Not OK - Cat ET indicates "SHORT" for the suspect cylinder.

  Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" for the proper procedure. Verify that the repair eliminates the problem.

  STOP

Test Step 8. Use the Injector Solenoid Test to Check the ECM for Open Circuits

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM.

2. Disconnect the J2/P2 ECM connectors. Remove the terminals for the supply wire and for the return wire of the suspect injector from the ECM connector.

3. Fabricate a jumper wire that is long enough to jumper two terminals at the ECM connector. Crimp connector sockets to each end of the jumper wire.

4. Install the jumper wire into the terminal locations for the suspect injector at the ECM connector. Connect the J2/P2 ECM connectors.

5. Restore electrical power to the ECM.

6. Perform the injector solenoid test at least two times. Record the results of the test.

   Note: Cat ET may report a "SHORT" for the injector that shares the supply with the suspect injector. Disregard the result for this injector.

7. Remove electrical power from the ECM.

Expected Result:

Cat ET displays "SHORT" for the cylinder with the jumper wire.

Results:

• OK - Cat ET displays "SHORT" for the suspect cylinder.

  Repair: The ECM is OK. There is a open circuit in the harness between the connector for the injector harness and the P2 ECM connector. Replace the engine harness or repair the engine harness, as required. Verify that the repair eliminates the problem.

  STOP

• Not OK - Cat ET does not display "SHORT" for the suspect cylinder.

  Repair: There is a problem with the ECM. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" for the correct procedure. Verify that the repair eliminates the problem.

  STOP

Test Step 9. Check the Injector Harness Under the Valve Cover for Open Circuits in the Injector Wires

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM.

2. Remove the valve cover.

3. Disconnect the connector for the problem injector.

4. Attach a jumper wire to both terminals at the harness side of the injector connector for the suspect injector.

5. Restore electrical power to the ECM.

6. Perform the injector solenoid test at least two times. Record the results of the test.

   Note: Cat ET may report a "SHORT" for the injector that shares the supply with the suspect injector. Disregard the result for this injector.

7. Remove electrical power from the ECM.

Expected Result:

Cat ET indicates "SHORT" for the cylinder with the suspect injector.

Results:

• OK - Cat ET reports "SHORT" for the suspect injector.

  Repair: The harness under the valve cover is OK. The problem is in the windings of the injector solenoid. Replace the injector. Verify that the repair eliminates the problem.

  STOP

• Not OK - Cat ET does not report "SHORT" for the suspect injector.

  Repair: The problem appears to be in the engine harness under the valve cover. Replace the engine harness under the valve cover or replace the engine harness under the valve cover. Run the injector solenoid test in order to check the installation of the new harness before installing the valve covers. Verify that the repair eliminates the problem.

  STOP

Test Step 10. Check the Injector Harness Under the Valve Cover for Short Circuits in the Injector Wires

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Electrical shock hazard. The electronic unit injector system uses 90-120 volts.

1. Remove electrical power from the ECM.

2. Remove the valve cover.

3. Disconnect the suspect injector from the wiring harness. Place the connector in a place that will not allow arcing during the test.

4. Restore electrical power to the ECM.

5. Perform the injector solenoid test at least two times.

Expected Result:

Cat ET indicates "OPEN" for the cylinder with the suspect injector.

Results:

• OK - Cat ET indicates "OPEN" for the suspect injector.

  Repair: The harness under the valve cover is OK. The problem is in the windings of the injector solenoid. Replace the injector. Verify that the repair eliminates the problem.

  STOP

• Not OK - Cat ET does not indicate "OPEN" for the suspect injector.

  Repair: The problem appears to be in the engine harness under the valve cover. Replace the engine harness under the valve cover or repair the engine harness under the valve cover. Run the injector solenoid test in order to check the installation of the new harness before installing the valve covers. Verify that the repair eliminates the problem.

  STOP