3508B Engine for 854G Wheel Dozers and 992G Wheel Loaders Caterpillar

The engine uses Electronic Fuel Injectors that are mechanically actuated and electronically energized. The Electronic 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. If a diagnostic is detected in the solenoid circuit, the ECM will disable that solenoid circuit. The ECM keeps the solenoid circuit disabled for 10 revolutions of the crankshaft. The ECM then tries to fire the injector. If the diagnostic is still present, the ECM will disable the circuit for another 10 revolutions of the crankshaft. This sequence of events will be repeated indefinitely until the problem is corrected.

The Cylinder Cutout Test on the Caterpillar Electronic Technician (ET) can be used to troubleshoot misfire problems. The Cylinder Cutout Test cuts out the 105 volt pulse to the injector solenoids. The solenoid is mounted on top of the fuel injector body.

Illustration 1	g00599630

Test Step 1. Check for Connector Damage.

1. Turn the keyswitch to the OFF position.

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

3. Thoroughly inspect the ECM connectors J1/P1 and J2/P2. Inspect all of the other connectors. Refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors" for details.

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

5. Check the ECM connector (allen head screw) for the proper torque of 6.0 N·m (55 lb in).

6. Check the customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

7. Check the harness and the wiring for abrasion and for pinch points.

Expected Result:

The connectors and wiring should be free of the following problems: damage, corrosion, abrasion and incorrect attachment.

Results:

• OK - The connectors and wiring are okay. Proceed to test step 2.

• Not OK - The connectors and/or wiring are not okay.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 2. Check for "ACTIVE" Diagnostic Codes.

1. Connect the Cat ET to the service tool connector. Start the Cat ET.

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

3. Turn the keyswitch to the ON position. The engine should be off.

4. Observe the diagnostic codes on the Cat ET.

Expected Result:

A CID-FMI 1-05 to 8-05 or 1-06 to 8-06 should not be logged.

Results:

• OK - A CID-FMI 1-05 to 8-05 or 1-06 to 8-06 is not logged. Logged diagnostic codes are not present. Proceed to test step 3.

• Not OK - A CID-FMI 1-05 to 8-05 or 1-06 to 8-06 is logged. There are logged diagnostic codes. Proceed to test step 5.

Test Step 3. Perform the Cylinder Cutout Test.

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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 keyswitch to the OFF position.

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

3. Verify that the ECM connector J2/P2 and the injector connectors J4/P4 through J11/P11 are properly connected.

4. Start the Cat ET.

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

6. Turn the keyswitch to the ON position.

7. Start the engine.

8. Apply a load to the engine.

9. Use the diagnostic test on the Cat ET to initiate the cylinder cutout test.

10. Check for a difference in the sound, in the feel, or in the power of the engine as each cylinder is cut out. The amount of change should be similar for all of the good cylinders. The amount of change should be minimal for a weak cylinder or for a bad cylinder.

11. Disable the override. Repeat the above steps for each cylinder (solenoid).

Expected Result:

The amount of change should be similar for all of the good cylinders. The amount of change should be minimal for a weak cylinder or for a bad cylinder.

Results:

• OK - There was a noticeable change in engine performance during the cylinder cutout test.

  Repair: The change in engine performance indicates that each cylinder is operating correctly. There may be an intermittent problem. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".

  Stop.

• Not OK - There was no noticeable change in engine performance during the cylinder cutout test for a specific cylinder. Proceed to test step 4.

Test Step 4. Check the Adjustment of the Fuel Injector and of the Engine Valve Lash Setting.

1. Turn the keyswitch to the OFF position.

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

3. Check the adjustment of the fuel injector and of the engine valve lash setting for the suspect cylinder. Refer to the Testing and Adjusting, "Fuel Injector Adjustment".

Expected Result:

The engine valve lash setting should be correct. The injectors should be okay.

Results:

• OK - The engine valve lash setting is correct. The injectors are okay.

  Repair: Recheck the system for any diagnostic codes.

  Stop.

• Not OK - The engine valve lash setting is not correct. The injectors are not okay. A problem is found with the injector.

  Repair: Adjust the engine valve lash. Refer to the Testing and Adjusting, "Valve Lash and Valve Bridge Adjustment". Repair the injector. If the problem is still present, replace the injector. If the new injector has a 4 Digit code that is different from the old injector, change the code in the ECM.

  Stop.

Test Step 5. Check the Resistance of the Harness from the Solenoid to the ECM Connector.

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This engine uses high voltage to control the fuel injectors. Disconnect electronic fuel injector enable circuit connector to prevent personal injury. Do not come in contact with the fuel injector terminals while the engine is running.

1. Turn the keyswitch to the OFF position.

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

3. Disconnect ECM connector J2/P2 and the injector connectors J4/P4 through J11/P11.

4. Measure the resistance at the ECM connector P2 between the following pins:
   • P2-16 and P2-5

   • P2-32 and P2-5

   • P2-26 and P2-17

   • P2-38 and P2-17

   • P2-37 and P2-27

   • P2-30 and P2-27

   • P2-31 and P2-39

   • P2-36 and P2-39

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance was greater than 20,000 Ohms. Proceed to test step 6.

• Not OK - The resistance was less than 20,000 Ohms.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 6. Check for a Short Circuit from the Harness to the Engine Ground.

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This engine uses high voltage to control the fuel injectors. Disconnect electronic fuel injector enable circuit connector to prevent personal injury. Do not come in contact with the fuel injector terminals while the engine is running.

1. For the 3508B, measure the resistance between the following sockets at ECM connector P2 and the engine ground: P2-5, P2-16, P2-17, P2-26, P2-27, P2-30, P2-31, P2-32, P2-36, P2-37, P2-38 and P2-39.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. Proceed to test step 7.

• Not OK - The resistance is less than 20,000 Ohms.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 7. Check for an Open Circuit in the Harness.

1. Use a suitable piece of wire to short socket 1 to socket 2 at each injector connector.

2. Measure the resistance at the ECM connector P2 between the power output for the individual solenoid and the solenoid return.

Expected Result:

The resistance should be less than 10 Ohms.

Results:

• OK - The resistance is less than 10 Ohms. Proceed to test step 8.

• Not OK - The resistance is greater than 10 Ohms.

  Repair: There is an open wire or excessive resistance in the circuit. Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

Test Step 8. Measure the Resistance at the Valve Cover Base.

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Personal injury can result from high voltage. The Electronic Control Module produces high voltage. Make sure the Electronic Control Module is not powered and the fuel injector solenoids are disconnected before proceeding.

1. Turn the keyswitch to the OFF position.

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

3. Ensure that the ECM connector J2/P2 is disconnected. Ensure that the injector connectors J4/P4 through J11/P11 are disconnected.

4. Measure the solenoid resistance between pin 1 and pin 2 at the injector connectors J4 through J11.

5. Record the measured resistance for each solenoid.

Expected Result:

The resistance should be between 0.6 and 3.6 Ohms.

Results:

• OK - The resistance is between 0.6 and 3.6 Ohms. Proceed to test step 9.

• Not OK - The resistance is not between 0.6 and 3.6 Ohms. Proceed to test step 10.

Test Step 9. Perform the Injector Solenoid Test.

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

1. Turn the keyswitch to the OFF position.

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

3. Ensure that the ECM connector J2/P2 is connected. Ensure that the injector connectors J4/P4 through J11/P11 are connected.

4. Start the Cat ET.

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

6. Turn the keyswitch to the ON position.

7. Use the diagnostic test on the Cat ET to initiate the injector solenoid test.

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

Expected Result:

As each solenoid is energized by the ECM, an audible click of the solenoid should be heard at the valve cover. The solenoids will be energized one at a time in the following numerical order: 1 to 8. There will be a momentary delay between each one.

Results:

• OK - The audible click is heard for each solenoid. Proceed to test step 3.

• Not OK - The audible click is not heard for each solenoid.

  Repair: Perform a diagnostic functional test. Perform the diagnostic functional test Troubleshooting, "Electrical Power Supply".

  Stop.

Test Step 10. Check the Resistance of the Injector Solenoid.

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This engine uses high voltage to control the fuel injectors. Disconnect the fuel enable circuit connector to prevent personal injury. Do not come in contact with the fuel injector terminals while the engine is running.

1. Turn the keyswitch to the OFF position.

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

3. Remove the valve cover of the suspected cylinder.

4. Remove the harness yoke from the solenoid terminals.

5. Measure the resistance between the two solenoid terminals on top of the injector. Record the resistance.

6. Measure the resistance from either solenoid terminal to the fuel injector body (metal).

7. Record the resistance.

8. Reconnect the harness yoke and install the valve cover.

Expected Result:

The resistance between the two solenoid terminals should be between 0.6 and 3.6 Ohms. The resistance from either solenoid terminal to the fuel injector body (metal) should be greater than 20,000 Ohms.

Results:

• OK - The resistance between the two solenoid terminals is between 0.6 and 3.6 Ohms. The resistance from either solenoid terminal to the fuel injector body (metal) is greater than 20,000 Ohms. All resistance readings are within limits. There is a problem in the valve cover base harness.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring.

  Stop.

• Not OK - The resistance between the two solenoid terminals is not between 0.6 and 3.6 Ohms. The resistance from either solenoid terminal to the fuel injector body (metal) is not greater than 20,000 Ohms. The injector has failed.

  Repair: Repair the fuel injector. If the problem is still present, replace the injector. If the new injector has a 4 Digit code that is different from the old injector, change the code in the ECM.

  Stop.