C27 and C32 Tier 4 Engines Caterpillar

This procedure covers the following diagnostic trouble 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.

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 schematic. 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	g02010956

Schematic for the injector solenoids

Test Step 1. Check for Logged Codes or Active Codes

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

2. Determine if a code is active or logged.

Expected Result:

A code is active or logged.

Results:

• A code is not active or logged. -

  Repair: There is not an electronic problem with the injectors at this time.

  STOP

• A -5 code or a -6 code is active or logged. - Proceed to Test Step 2.

Test Step 2. Inspect the Wiring Harness Between the ECM and the Valve Cover Base

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

1. Turn the keyswitch to the OFF position.

2. Thoroughly inspect the connectors. 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 and each of the wires that are associated with injector solenoids.

4. Check the allen head screw on the ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

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

Results:

• OK - The connectors and the wiring appear to be OK. Proceed to Test Step 3.

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

  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 coupled. Perform an injector solenoid test in order to verify that the problem has been corrected.

  STOP

Test Step 3. 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 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 electrical power from the engine ECM.

3. Disconnect the connectors of the injector harness at the valve cover base.

4. Fabricate a jumper wire long enough to create a short circuit across the different terminal locations at the connector of the injector harness. Crimp connector pins on both ends of the jumper wire.

5. Insert one end of the jumper wire into the connector socket for the suspect injector supply wire. Insert the other end of the jumper wire into the connector socket for the suspect injector return wire. The jumper will bypass the injector solenoid with a short.

6. Restore electrical power to the engine ECM.

7. Turn the keyswitch to the ON position.

8. Perform the "Injector Solenoid Test" in Cat ET.

9. Repeat this test for each suspect circuit.

   Note: Stop the "Injector Solenoid Test" before handling the jumper wire. Restore the wiring to the original configuration.

Expected Result:

Cat ET displays a -6 code for each of the circuits that were jumpered.

Results:

• OK - Cat ET displays a -6 code for each circuit that was jumpered. The harness between the ECM and the connector does not have an open circuit. Proceed to Test Step 4.

• Not OK - Cat ET does not display a -6 code for the cylinder with the jumper wire.

  Repair: There is a problem in the engine harness. Repair the harness or replace the harness between the ECM and the valve cover base. Perform an injector solenoid test in order to verify that the problem has been corrected.

  STOP

Test Step 4. Check the Harness between the ECM and the Valve Cover Base for a Short 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. Remove electrical power from the engine ECM.

3. Disconnect the connectors of the injector harness at the valve cover base.

4. Restore electrical power to the engine ECM.

5. Turn the keyswitch to the ON position.

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

Expected Result:

All of the cylinders indicate a -5 code on Cat ET.

Results:

• OK - All cylinders for the appropriate cylinder bank indicate a -5 code on Cat ET. The harness between the ECM and the connector does not have a short circuit. Proceed to Test Step 5.

• Not OK - One or more cylinders indicate a -6 code on Cat ET. Note the cylinders that indicate "Short".

  Repair: The problem is in the wiring between the ECM and the valve cover base, or the ECM is not operating properly.

  Test the harness wiring for the suspect cylinders for a short circuit.

  If a short circuit in the harness wiring is discovered, repair the wiring or replace the wiring.

  Perform an injector solenoid test in order to verify that the problem has been corrected.

  If the problem still exists, proceed to Test Step 7.

Test Step 5. Check the Injector Harness under the Valve Cover for a Short 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. Remove electrical power from the engine ECM.

3. Remove the valve cover in order to gain access to the suspect injector.

4. Disconnect the harness connector from the suspect injector.

   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.

5. Turn the keyswitch ON.

6. 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 that is not connected.

Results:

• OK - Cat ET displays "Open" for the solenoid that is not connected. Proceed to Test Step 6.

• Not OK - Cat ET displays "Short" for the solenoid that is not connected. There is a problem with the injector harness under the valve cover. Replace the harness or repair the harness.

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

  STOP

Test Step 6. Check the Injector Harness under the Valve Cover for an Open Circuit

Illustration 2	g02047716
Harness connector for an injector (Terminal 1) Supply for solenoid 1 (Terminal 2) Supply for solenoid 2 (Terminal 3) Return for solenoid 1 (Terminal 4) Return for solenoid 2

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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. Remove electrical power from the engine ECM.

3. Determine the appropriate terminals for the solenoid with the code. Refer to Table 2 for the proper terminal connections. Connect a jumper wire between the terminal for the supply and the terminal for the return. The jumper will replace the injector solenoid with a short circuit.

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 connector with the jumper wire that is installed between the terminals.

Results:

• OK - Cat ET displays "Short " for the connector with the jumper wire that is installed between the terminals. The wiring is OK. Proceed to Test Step 7.

• Not OK - Cat ET displays "Open " for the connector with the jumper wire that is installed between the terminals.

  Repair: The wiring has an open. Repair the harness or replace the harness under the valve cover. Perform an injector solenoid test in order to verify that the problem has been corrected.

  STOP

Test Step 7. 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. Ignore the codes and clear the codes after you complete this Test Step.

2. Disconnect the P2 connector.

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.

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

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

7. Turn the keyswitch ON.

8. 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 that has been installed between the terminals. Cat ET displays "open" when the P2 connector is disconnected.

Results:

• OK - Cat ET displays "Short" for the solenoid with the jumper wire that has been installed between the terminals. Cat ET will display "Open" when P2 connector is not connected to the ECM.

  Repair: The problem is in the injector. Replace the injector. Perform an injector solenoid test in order to verify that the problem has been corrected.

  STOP

• Not OK - Cat ET does not display "Short" for the solenoid with the jumper wire that has been installed between the terminals. Cat ET does not display "Open" when P2 is not connected to the ECM.

  Repair: There may be a problem with the ECM. Before you consider replacing the ECM, consult the Dealer Solution Network (DSN).

  STOP