3406E and 3456 Generator Set Engines Caterpillar


Injector Solenoid Circuit - Test

Usage:

3406E 8AZ
System Operation Description:

The engine has electronic unit injectors that are mechanically actuated and electronically energized. The Electronic Control Module 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 105 volt pulse can be individually cut out to aid in troubleshooting misfire problems.

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 temporarily disable the solenoid circuit. The ECM will then enable the solenoid. If the short circuit remains this sequence of events will be repeated until the problem is corrected.



Illustration 1g00744368

Test Step 1. INSPECT ELECTRICAL CONNECTORS AND WIRING

    ------ WARNING! ------

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


  1. Verify that no circuit breakers are tripped.

  2. Turn the Engine Control Switch (ECS) to the OFF/RESET position.

  3. Turn the circuit breaker for the battery to the OFF position.

  4. Thoroughly inspect ECM connector J2/P2 and unit injector connector J91/P91. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

  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 inserted and coupled. The harness and wiring are free of corrosion, of abrasion, and of pinch points.

Results:

  • OK - Proceed to Test Step 2.

  • Not OK -

    Repair: Repair the circuit. 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 the Caterpillar Electronic Technician (ET) to the service tool connector.

  2. Turn the circuit breaker for the battery to the ON position.

  3. Turn the ECS to the STOP position.

  4. Observe the diagnostic codes on Cat ET.

Expected Result:

One or more of the following diagnostic codes have been logged:

  • 1-05 "Injector Cylinder 1 open circuit" through 6-05 "Injector Cylinder 6 open circuit"

  • 1-06 "Injector Cylinder 1 short" through 6-06 "Injector Cylinder 6 short"

Results:

  • OK - Diagnostic codes that are associated with the injectors have been logged. Proceed to Test Step 3.

  • Not OK - Proceed to Test Step 4.

Test Step 3. PERFORM THE INJECTOR SOLENOID TEST



Illustration 2g00663576
"Injector Solenoid Test" screen in Cat ET

Note: This test will help the service technician verify that the ECM can fire the injector solenoids. Do not try to manually crank the engine during this test. The ECM will terminate the Injector Solenoid Test.

  1. Start the engine and allow the engine to reach normal operating temperatures.

  2. Turn the ECS to the OFF/RESET position.

  3. Connect Cat ET to the service tool connector.

  4. Turn the ECS to the STOP position.

  5. Use "Diagnostic Tests" on Cat ET to initiate the "Injector Solenoid Test".

  6. As each solenoid is energized by the ECM an audible click can be heard at the valve mechanism cover. Listen for a click at each valve mechanism cover. There will be a momentary delay between each one. A black square will appear over the cylinder number on Cat ET when the cylinder is being fired.

    Note: Repeat the Injector Solenoid Test a few times in order to verify that the ECM is energizing each solenoid.

Expected Result:

All cylinders indicate "OK".

Results:

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

    STOP

  • Not OK -

    Repair: Note the cylinders that indicate "OPEN" and/or "SHORT".

    Proceed to Test Step 5.

Test Step 4. PERFORM THE CYLINDER CUTOUT TEST



Illustration 3g00663575
"Automated Cylinder Cutout Test" screen in Cat ET


    NOTICE

    Engine power is reduced when a properly functioning cylinder is cut out. Make sure that you will not damage auxiliary or driven equipment if the engine power is suddenly reduced.


  1. Turn the circuit breaker for the battery to the OFF position.

  2. Turn the ECS to the OFF/RESET position.

  3. Verify that the ECM connector J2/P2 and the injector connectors J91/P91 are properly connected.

  4. Turn the circuit breaker for the battery to the ON position.

  5. Start the engine.

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

  7. Apply a load to the engine.

  8. After the engine is warmed to operating temperature, access the "Cylinder Cutout Test" by accessing the following display screens in order:

    • "Diagnostics"

    • "Diagnostic Tests"

    • "Cylinder Cutout Test"

  9. Set the engine speed to 1800 rpm.

  10. Select the start button at the bottom of the screen for the "Cylinder Cutout Test".

  11. Select the "4 Cylinder Cutout Test" which is the default test.

  12. Follow the instructions that are provided in the "Cylinder Cutout Test". The "Cylinder Cutout Test" is 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 Cat ET screen for the "Cylinder Cutout Test". The "4 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.

    Note: Check for a difference in the sound, feel, or power of the engine as each cylinder is cut out. The amount of change should be similar for all of the properly operating cylinders. The amount of change should be minimal for a weak cylinder or a misfiring cylinder.

Expected Result:

All cylinders indicate "OK" on Cat ET.

Results:

  • OK - The test indicates that all of the cylinders are operating correctly.

    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".

    STOP

  • Not OK - There was no change in the sound, feel, or power of the engine as one of the cylinder's was cut out. Proceed to Test Step 5.

Test Step 5. CHECK THE ENGINE HARNESS FROM P2 TO P91 FOR SHORT CIRCUITS

  1. Turn the ECS to the OFF/RESET position.

  2. Disconnect unit injector connector J91/P91.

  3. Turn the ECS to the STOP position.

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

Expected Result:

All cylinders indicate "Open".

Results:

  • OK - Proceed to Test Step 6.

  • Not OK - All injectors do not indicate "Open".

    Repair: Note the cylinders that indicate a short circuit.

    Proceed to Test Step 7.

Test Step 6. CHECK THE ENGINE HARNESS FROM P2 TO P91 FOR AN OPEN CIRCUIT



Illustration 4g00663572
Injector connector for engine harness

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Disconnect unit injector connector J91/P91.

  3. Turn the ECS to the STOP position.

  4. Fabricate a jumper wire 100 mm (4 inch) long. Crimp a Deutsch pin to both ends of the wire.

  5. Insert one end of the jumper wire into the "Injector Common" socket of the problem injector. Insert the other end of the jumper wire into the socket of injector connector P300 that goes to the problem injector. For example, if Injector 5 is the problem injector, insert the jumper from terminal 5 of the injector connector P91 to terminal 8 of the injector connector P91.

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

  7. Repeat this test for each suspect Injector. Ensure that the "Injector Solenoid Test" is disabled before handling the jumper wires.

Expected Result:

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

Results:

  • OK - Proceed to Test Step 9.

  • Not OK - There is an open circuit in the valve cover base harness or the injector solenoid. Proceed to Test Step 9.

Test Step 7. CHECK THE ECM FOR SHORT CIRCUITS

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Ensure that the ECM connector J2/P2 is disconnected and that the unit injector connector J91/P91 is disconnected.

  3. Turn the ECS to the STOP position.

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

Expected Result:

All cylinders indicate "OPEN" when the P2 ECM connector 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: Repair the harness or replace the harness. verify that the repair has eliminated the problem.

    STOP

  • Not OK - The ECM is suspect.

    Repair: Temporarily connect a test ECM. Remove all jumpers and replace all connectors. Recheck the system for active diagnostic codes. Repeat the Test Step. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. Verify that the repair eliminates the problem.

    STOP

Test Step 8. EVALUATE THE SYMPTOMS

Expected Result:

Choose from these possible results:

Result 1 Test Step 6 indicated that only one injector had an "OPEN" or "SHORT", or that one injector had an "OPEN" but the other injector on the injector common line had a "SHORT".

Result 2 Test Step 6 indicated that two injectors that share an injector common line are open.

Result 3 Test Step 6 indicated that two injectors that share an injector common line are shorted.

Results:

  • Result 1 - Proceed to Test Step 10.

  • Result 2 - Proceed to Test Step 11.

  • Result 3 - Proceed to Test Step 12.

Test Step 9. CHECK THE ECM FOR AN OPEN CIRCUIT

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Disconnect the ECM connector J2/P2.

  3. Use a jumper wire to short between the socket of the injector and the common socket of the suspect injector.

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

Expected Result:

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

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 ECM is OK.

    Repair: Replace the engine harness or repair the engine harness, as required. Verify that the repair eliminates the problem.

    STOP

  • Not OK - The ECM is suspect.

    Repair: Temporarily connect a test ECM. Remove all jumpers and replace all connectors. Recheck the system for active diagnostic codes. Repeat the Test Step. If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. Verify that the repair eliminates the problem.

    STOP

Test Step 10. CHECK THE INJECTOR HARNESS UNDER THE VALVE COVER

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Remove the valve cover.

  3. Disconnect the harness from the problem injector. Disconnect the harness from the other injector that has the same injector common line.

  4. Thoroughly clean the terminals of both injectors and the harness.

  5. Exchange the harness between the two injectors that share the common line.

  6. Turn the ECS to the STOP position.

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

Expected Result:

Exchanging the harness between the two injectors caused the problem to move to the other injector on Cat ET.

Results:

  • OK -

    Repair: Replace the faulty injector. Restore the wiring to the proper injectors. Verify that the repair eliminates the problem.

    STOP

  • Not OK -

    Repair: Perform the following repair:

    Replace the injector harness under the valve cover. Verify that the repair eliminates the problem.

    STOP

Test Step 11. CHECK THE ENGINE HARNESS UNDER THE VALVE COVER FOR AN OPEN CIRCUIT IN THE COMMON LINE



Illustration 5g00663574
Harness terminals of Electronic Unit Injector

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Remove the valve cover.

  3. Disconnect each of the injectors that indicate an "OPEN" from the wiring harness. Ensure that each of the connectors from the disconnected injector harness does not touch other components and short to ground.

  4. Attach a jumper wire to both terminals of the injector harness for the two injectors that share an injector common line.

  5. Turn the ECS to the STOP position.

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

Expected Result:

The cylinders with the short in place indicate an "OPEN".

Results:

  • OK -

    Repair: Replace the engine harness under the valve cover. Use the Injector Solenoid Test to check the installation of the new harness before installing the valve covers. Verify that the repair eliminates the problem.

    STOP

  • Not OK - Both injectors indicate "SHORT".

    Repair: Both injectors indicate "SHORT". Replace Both injectors. Verify that the repair eliminates the problem.

    STOP

Test Step 12. CHECK THE ENGINE HARNESS UNDER THE VALVE COVER FOR SHORT CIRCUITS IN THE INJECTOR WIRES

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  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 other components and short to ground.

  4. Turn the ECS to the STOP position.

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

Expected Result:

Both cylinders indicate an "OPEN".

Results:

  • OK - Leave the injector wires disconnected. Neither of the injector wires are shorted to the engine. Proceed to Test Step 13.

  • Not OK - The injector harness is suspect.

    Repair: Replace the injector harness under the valve cover. Use the Injector Solenoid Test to check the installation of the new harness before installing the valve covers. Verify that the repair eliminates the problem.

    STOP

Test Step 13. CHECK FOR A SHORT CIRCUIT IN THE INJECTOR COMMON LINE TO THE ENGINE

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Disconnect the J2/P2 ECM connector.

  3. Locate the common line for the problem injector in the P2 connector. Measure the resistance from the terminal to the engine ground stud connection.

Expected Result:

The multimeter indicates that the resistance is greater than 10 Ohms.

Results:

  • OK - Reconnect the engine harness to the ECM. Proceed to Test Step 14.

  • Not OK -

    Repair: Replace the injector harness under the valve cover.

    Verify that the repair eliminates the problem.

    STOP

Test Step 14. CHECK FOR A SHORT CIRCUIT IN THE INJECTOR

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Reconnect one of the two disconnected injectors.

  3. Turn the ECS to the STOP position.

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

Expected Result:

The reconnected injector indicates a "SHORT".

Results:

  • OK -

    Repair: Replace the injector. Verify that the repair eliminates the problem.

    STOP

  • Not OK - The injector is OK. Proceed to Test Step 15.

Test Step 15. CHECK FOR A SHORT CIRCUIT IN THE OTHER INJECTOR

    ------ WARNING! ------

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


  1. Turn the ECS to the OFF/RESET position.

  2. Reconnect the other disconnected injector.

  3. Turn the ECS to the STOP position.

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

Expected Result:

The reconnected injector indicates a "SHORT".

Results:

  • OK -

    Repair: Replace the faulty injector. Restore the wiring to the proper injectors. Verify that the repair eliminates the problem.

    STOP

  • Not OK - This injector is OK.

    STOP

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