C13 and C15 On-highway Engines Caterpillar

This procedure covers the following diagnostic codes:

Background Information

These engines have Electronic Unit Injectors (EUI) that are electronically controlled. Each injector contains two solenoids. The Engine Control Module (ECM) sends 105 V pulses to each injector solenoid. The pulses are sent at the proper time and at the correct duration for a given engine load and speed.

The ECM monitors the current flow through the circuit for each solenoid. If low current flow is detected, a diagnostic code is activated. The ECM continues to try to fire the injector.

If high current flow is detected, a diagnostic code is activated. The ECM will disable the solenoid circuit in order to prevent damage from the high current flow. However, 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.

Ensure that the fuel system is not restricted. A restricted fuel supply to the injectors will cause the injector solenoids to overheat and possibly fail. A sufficient fuel supply to the injector solenoids is necessary to cool the solenoids during operation.

Typically, problems with an injector solenoid occur when the engine is warmed up and/or when the engine is under vibration (heavy loads). Perform this procedure when the engine is at normal operating temperature. Pay careful attention to the condition of the wiring and the connectors as you perform this procedure. The wiring and/or the connectors may have problems that only occur during vibration.

Diagnostic Tests on the Caterpillar Electronic Technician (ET)

Cat ET includes the following test that aids in troubleshooting injector solenoids:

Injector Solenoid Test - The "Injector Solenoid Test" identifies an open circuit or a short circuit in the circuits for the injector solenoids. The test is performed 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 indicates the status of the solenoid as "OK", "Open", or "Short".

Note: Refer to the following schematics. Two injector solenoids share a common supply wire. For this reason, an open circuit or a short circuit in a supply wire could cause diagnostic codes for two cylinders.

Illustration 1	g01373808
Schematic for the injectors on C13 engines

Illustration 2	g01373904
Schematic for the injector solenoids on C15 engines

Test Step 1. Test the Fuel Supply at Secondary Filter Base

1. Test the fuel supply at the sampling port located on the secondary fuel filter base. T

Expected Result:

The fuel supply pressure should not exceed 655 kPa (95 psi) at high idle.

Results:

• No - The fuel supply pressure does not exceed 655 kPa (95 psi). Proceed to Test Step 2.

• Yes - The fuel supply pressure exceeds 655 kPa (95 psi).

  Repair: Replace the fuel filters and check the fuel system for restrictions.

  STOP

Test Step 2. Determine if the Code is Active or Logged

1. Establish communication between Cat ET and the ECM . Refer to Troubleshooting, "Electronic Service Tools", if necessary.

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

3. Determine if the code is active or logged.

Expected Result:

The code is logged.

Results:

• Logged code - Do not turn off the engine. Proceed to Test Step 3.

• Active code - Do not turn off the engine. Proceed to Test Step 6.

Test Step 3. Check the External Engine Harness

1. Inspect the injector wiring harness between the ECM and the valve cover. Look for these problems:

   • Improper routing of the wire harness

   • Missing clamps or other hardware

   • Loose connectors or damaged connectors

   • Damage that is caused by excessive heat

   • Damage that is caused by chafing

2. Slowly wiggle the wiring harness and the connectors between the P2 connector and the valve cover. Pay particular attention to the wiring near each connector. As you wiggle the wiring, look for the code to become active.

   Continue with this procedure if the code does not become active. If the code becomes active, note the location of the problem. Proceed to the appropriate result for this Test Step.

3. Refer to the appropriate schematic diagram. Identify the wires at each connector that relate to the cylinder that has the code. Perform the following procedure for the wires at each connector:

   1. Inspect the seal around each wire. Verify that the seal is sealing correctly, properly installed, and not damaged.

   2. Pull on each wire in order to verify that the wire and the terminal are correctly installed.

Expected Result:

The code becomes active when the wiring is moved. Alternatively, there is a problem with a connector.

Results:

• Yes - There is a problem with the external engine harness.

  Repair: Stop the engine. Repair the wiring problem. Replace parts, if necessary. Start the engine. Verify that the problem is resolved.

  STOP

• No - The external engine harness is OK. Note the cylinder that has the code. Stop the engine. Proceed to Test Step 4.

Test Step 4. Check the Harness Under the Valve Cover

1. Remove the valve cover.

2. Carefully perform a visual inspection of the wiring harness under the valve cover. Look for the following problems:

   • Improper routing of the wire harness

   • Missing clamps or other hardware

   • Loose connectors or damaged connectors

   • Damage that is caused by excessive heat

   • Damage that is caused by chafing

3. Inspect the connectors on the harness under the valve cover. Perform the following procedure on each wire that relates to the cylinder that has the code:

   1. Inspect the seal around each wire. Verify that the seal is sealing correctly, properly installed, and not damaged.

   2. Pull on each wire in order to verify that the wire and the terminal are correctly installed.

   3. Disconnect the harness connector from the suspect injector. When the injector faults are present, carefully inspect the injector connector pins for arcing.

   4. Connect the harness connector to the injector. Verify that the clip works correctly.

Expected Result:

There is a problem with the wiring harness under the valve cover.

Results:

• Yes - There is a problem with the wiring harness under the valve cover, or pin arcing is present.

  Repair: Correct the problem. Replace the injector and injector harness if pin arcing is present. Replace parts, if necessary. Install the valve cover. Start the engine. Allow the engine to warm up to normal operating temperature. Verify that the code does not recur.

  STOP

• No - The wiring harness under the valve cover appears to be OK.

  Repair: Start the "Injector Solenoid Test". Allow the test to continue until each cylinder is activated at least two times.

  If a solenoid fails the injector solenoid test, there is a problem with the harness under the valve cover. Correct the problem. Replace parts, if necessary. Install the valve cover. Start the engine. Allow the engine to warm up to normal operating temperature. Verify that the code does not recur.

  If all of the solenoids pass the injector solenoid test, proceed to Test Step 5.

Test Step 5. Check the Components

1. Clear the logged codes. When injector faults are present, inspect the injector connector pins for evidence of arcing.

2. Temporarily install a new injector in place of the suspect injector. Replace the injector harness if pin arcing is present.

3. Install the valve cover.

4. Start the engine. Allow the engine to warm up to normal operating temperature. Perform a test drive of the vehicle, when possible.

5. Look for the original diagnostic code to recur.

Expected Result:

The original diagnostic code does not recur.

Results:

• OK - The original diagnostic code does not recur. The problem appears to be resolved. Return the engine to service.

  STOP

• Not OK - The original diagnostic code recurs.

  Repair: Perform the following procedure:

  1. Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode".

  2. Start the "Injector Solenoid Test". Allow the test to continue until each solenoid is activated at least two times.

     If the test ECM fixes the problem, connect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.

  STOP

Test Step 6. Check the External Engine Harness

1. Wiggle the injector wiring harness between the ECM and the valve cover. Look for these problems.

   • Improper routing of the wire harness

   • Missing clamps or other hardware

   • Loose connectors or damaged connectors

   • Damage that is caused by excessive heat

   • Damage that is caused by chafing

2. Refer to the appropriate schematic diagram. Identify the wires at each connector that relate to the solenoid that has the code. Perform the following procedure for the wires at each connector:

   1. Inspect the seal around each wire. Verify that the seal is sealing correctly.

   2. Pull on each wire in order to verify that the wire and the terminal are correctly installed.

Expected Result:

The code becomes inactive when the wiring is moved.

Results:

• Yes - The code becomes inactive when the wiring is moved.

  Repair: Stop the engine. Repair the problem with the harness. Replace parts, if necessary. Start the engine. Verify that the problem is resolved.

  STOP

• No - Short Code - A short code remains active. Note the cylinder that indicates "Short". Stop the engine. Proceed to Test Step 10.

• No - Open Code - An open code remains active. Note the cylinder that indicates "Open". Stop the engine. Proceed to Test Step 7.

Test Step 7. Check the External Engine Harness for an Open Circuit

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Electrical shock hazard. The electronic unit injector system uses 90-120 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 harness connectors for the injector solenoids.
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   Illustration 3	g01170844
   Location of the jumper wire on the harness for the injectors

3. Refer to the applicable schematic diagram. Determine the appropriate terminals for the solenoid with the code. Refer to Illustration 3. Connect a jumper wire between the supply wire and the return wire for the solenoid. This will replace the solenoid with a short circuit.

4. Turn the keyswitch to the ON position.

5. Activate the "Injector Solenoid Test". Allow the "Injector Solenoid Test" to continue until each solenoid is activated at least two times.

Expected Result:

Cat ET displays "Short" for the solenoid with the jumper wire.

Results:

• Yes - Cat ET displays "Short" for the solenoid with the jumper wire. The harness between the ECM and the connector does not have an open circuit. Remove the jumper wire. Connect the connectors. Proceed to Test Step 8.

• No - Cat ET displays "Open" for the solenoid with the jumper wire. The ECM did not detect the jumper wire. Proceed to Test Step 9.

Test Step 8. Check the Injector Harness under the Valve Cover for an Open Circuit

Show/hide table

Electrical shock hazard. The electronic unit injector system uses 90-120 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. Carefully perform a visual inspection of the wiring harness under the valve cover. Look for the following problems:

   • Improper routing of the wire harness

   • Missing clamps or other hardware

   • Loose connectors or damaged connectors

   • Damage that is caused by excessive heat

   • Damage that is caused by chafing

   • Evidence of arcing on injector connector pins

4. Identify the harness connector for the solenoid that has the code. Perform the following procedure on each wire that relates to the solenoid that has the code:

   1. Inspect the seal around each wire. Verify that the seal is sealing correctly, installed properly, and not damaged.

   2. Pull on each wire in order to verify that the wire and the terminal are correctly installed.

   3. Disconnect the harness connector from the suspect injector.

   4. When injector faults are present, inspect the injector connector pins for arcing.
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   Illustration 4	g01322701
   Harness connector for an injector

5. Refer to the appropriate schematic diagram. Determine the appropriate terminals for the solenoid with the code. Refer to Illustration 3. Connect a jumper wire between the terminal for the supply and the terminal for the return. This will replace the injector solenoid with a short circuit.

6. Turn the keyswitch ON.

7. Activate the "Injector Solenoid Test". Allow the "Injector Solenoid Test" to continue until each solenoid is activated at least two times.

Expected Result:

Cat ET displays "Open" for the solenoid with the jumper wire.

Results:

• OK - Cat ET displays "Open" for the solenoid with the jumper wire. There is a problem with the injector harness under the valve cover. There may be a problem with a connector. Replace the suspect injector and injector harness if pin arcing is present.

  Repair: Repair the wiring and/or the connector, when possible. Replace parts, if necessary. Verify that the problem is resolved.

  STOP

• Not OK - Cat ET displays "Short" for the solenoid with the jumper wire. The wiring is OK.

  Repair: Replace the faulty injector. Replace the suspect injector and injector harness if pin arcing is present. Verify that the problem is resolved.

  STOP

Test Step 9. Check the ECM for Proper Operation

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

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

   Note: When the P2 connector is disconnected, numerous diagnostic codes will be generated when the keyswitch is turned ON. This is normal. Ignore the codes and clear the codes after you complete this Test Step.

2. Disconnect the P2 connector.

3. Use a jumper wire in order to create a short circuit on J2 between the terminals for the solenoid supply and the solenoid return.

4. Turn the keyswitch ON.

5. Activate the "Injector Solenoid Test". Allow the "Injector Solenoid Test" to continue until each solenoid is activated at least two times.

Expected Result:

Cat ET displays "Short" for the solenoid with the jumper wire.

Results:

• Yes - Cat ET displays "Short" for the solenoid with the jumper wire. The ECM detected the short circuit.

  Repair: There is an open circuit in the external engine harness for the injectors. There may be a problem in a connector.

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

  Verify that the problem is resolved.

  STOP

• No - Cat ET displays "Open" for the solenoid with the jumper wire. The ECM did not detect the jumper wire.

  Repair: Perform the following procedure:

  1. Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode".

  2. Activate the "Injector Solenoid Test". Allow the "Injector Solenoid Test" to continue until each solenoid is activated at least two times.

     If the test ECM fixes the problem, connect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. Verify that the problem is resolved.

  STOP

Test Step 10. Check the External Engine Harness for a Short Circuit

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

1. Turn the keyswitch OFF. A strong electrical shock hazard is present if the keyswitch is not turned off.
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   Illustration 5	g01424960
   Typical harness connector for the injectors

2. Disconnect all of the harness connectors for the injector solenoids. This will disconnect the valve cover harness from the engine harness.

3. Turn the keyswitch ON.

4. Activate the "Injector Solenoid Test". Allow the "Injector Solenoid Test" to continue until each solenoid is activated at least two times.

Expected Result:

All cylinders indicate "Open" on Cat ET.

Results:

• OK - All cylinders indicate "Open" on Cat ET. Connect the harness connectors. Proceed to Test Step 11.

• Not OK - One or more cylinders indicate "Short" on Cat ET. Note the cylinders that indicate "Short". Connect the harness connectors. Proceed to Test Step 12.

Test Step 11. Check the Harness under the Valve Cover for a Short Circuit

Show/hide table

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

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

2. Remove the valve cover.

3. Disconnect the harness connector for each injector solenoid that indicates a "Short" on Cat ET. Ensure that each disconnected connector does not touch other components and create a short circuit. When injector faults are present, inspect the injector connector pins for arcing.

4. Verify that the injector seal is properly installed, sealing correctly, and not damaged.

5. Turn the keyswitch ON.

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

Expected Result:

All of the injector solenoids that were disconnected indicate "Open" on Cat ET.

Results:

• OK - All of the injector solenoids that were disconnected indicate "Open" on Cat ET.

  Repair: Replace the faulty injector.

  Perform the "Injector Solenoid Test".

  Verify that the problem is resolved.

  STOP

• Not OK - At least one of the injector solenoids that were disconnected still indicate "Short" on Cat ET. There is a problem with the wiring harness inside the valve cover. There may be a problem with a connector. There are signs of arcing on the injector pins.

  Repair: Inspect the connectors for moisture and for corrosion. Repair the wiring and/or the connector, when possible. Replace the suspect injector and/or injector harness assembly. Replace parts, if necessary.

  Verify that the problem is resolved.

  STOP

Test Step 12. Check the ECM for Proper Operation

Show/hide table

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

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

   Note: When the P2 connector is disconnected, numerous diagnostic codes will be generated when the keyswitch is turned to the ON position. This is normal. Ignore the codes and clear the codes after you complete this Test Step.

2. Disconnect the P2 connector.

3. Turn the keyswitch ON.

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

Expected Result:

All injector solenoids indicate "Open" when the P2 connector is disconnected.

Results:

• OK - All injector solenoids indicate "Open" when the P2 connector is disconnected. There is a short circuit in the engine harness. There may be a problem with a connector.

  Repair: Inspect the connectors for moisture and for corrosion. Repair the wiring and/or the connector, when possible. Replace parts, if necessary. Clear all diagnostic codes after you complete this test step.

  Verify that the problem is resolved.

  STOP

• Not OK - At least one injector solenoid does not indicate "Open". There is a problem with the ECM.

  Repair: Perform the following procedure:

  1. Temporarily connect a test ECM. Refer to Troubleshooting, "Test ECM Mode".

  2. Activate the "Injector Solenoid Test". Allow the "Injector Solenoid Test" to continue until each solenoid is activated at least two times.

     If the test ECM fixes the problem, connect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM.

  Verify that the problem is resolved.

  STOP