3412E Engine for Caterpillar Built Machines Caterpillar

The engine has Hydraulic Electronic Unit Injectors (HEUI). 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. The solenoid is mounted on top of the fuel injector body. 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 and the ECM continues to try to fire the fuel injector. If a short is detected, a diagnostic code is generated and the ECM temporarily disables the solenoid circuit. The ECM will then enable the solenoid circuit. This sequence of events will be repeated until the problem is corrected.

Illustration 1	g00712248
Schematic

Illustration 2	g00893822
12 cylinder P2 ECM connector (5) Solenoid 1/3 Return (11) Solenoid 2/4 Return (12) Solenoid 12 Power (16) Solenoid 1 Power (17) Solenoid 5/7 Return (18) Solenoid 10 Power (21) Solenoid 6/8 Return (22) Solenoid 8 Power (26) Solenoid 3 Power (27) Solenoid 9/11 Return (28) Solenoid 6 Power (31) Solenoid 11 Power (32) Solenoid 5 Power (33) Solenoid 10/12 Return (34) Solenoid 4 Power (37) Solenoid 9 Power (38) Solenoid 7 Power (40) Solenoid 2 Power

Test Step 1. Inspect Electrical Connectors And Wiring

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

1. Turn the keyswitch to the OFF/RESET position. A strong electrical shock hazard is present if the ignition key is not turned OFF.

2. Thoroughly inspect the J2/P2 ECM connector and the J52/P52 through J58/P58 unit injector connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Check the harness and wiring for abrasion and pinch points from the injectors to the ECM.

Expected Result:

All connectors, pins, and sockets should be completely inserted and coupled. The harness and wiring should be free of corrosion, abrasion, and 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 (Cat ET) to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Observe the diagnostic codes on Cat ET.

Expected Result:

The following diagnostic codes should not be logged:

• 1-05 Injector Cylinder 1 open circuit through 12-05 Injector Cylinder 12 open circuit

• 1-06 Injector Cylinder 1 short through12-06 Injector Cylinder 12 short

Results:

• OK - None of the diagnostic codes are logged. Proceed to Test Step 3.

• Not OK - One or more of the diagnostic codes are logged. Proceed to Test Step 4.

Test Step 3. Perform the Injector Solenoid Test

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

1. Turn the keyswitch to the ON position.

2. Perform the Injector Solenoid Test on Cat ET.

3. 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.

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

Expected Result:

As each solenoid is energized by the ECM, an audible click of the solenoid should be heard. The solenoids will be energized one at a time in numerical order from 1 through 12. There will be a momentary delay between each one.

Results:

• OK - All of the solenoids were energized. Proceed to Test Step 9.

• Not OK - One or more of the solenoids did not energize. Proceed to Test Step 4.

Test Step 4. Check the Harness Resistance

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

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

2. Disconnect the J2/P2 ECM connector.

3. Measure the resistance at the P2 ECM connector between the terminals for each solenoid.

   Refer to Illustration 1.

Expected Result:

The resistance should be less than 10 Ohms.

Results:

• OK - Proceed to Test Step 5.

• Not OK - There is an open in the harness or there is an open in the injector solenoid. Proceed to Test Step 6.

Test Step 5. Check the Harness for Shorts

1. Disconnect the J52/P52 through J58/P58 unit injector connectors.

2. Measure the resistance at the P2 ECM connector between the terminals for each solenoid.

   Refer to Illustration 1.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - There are no shorts in the harness or the connectors. Proceed to Test Step 7.

• Not OK - There is a short in the harness or the connectors.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

Test Step 6. Isolate the 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/RESET position.

2. Disconnect the suspect injector at the valve cover base.

3. Measure the solenoid resistance of the suspect injector at the valve cover base (J52 through J58). Refer to Illustration 1.

Expected Result:

Resistance should be less than 3.6 Ohms.

Results:

• OK - There is an open circuit or excessive resistance in the harness or the connectors.

  Repair: Repair the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect".Verify that the repair eliminates the problem.

  Stop.

• Not OK - There is an open circuit in the valve cover base harness or the injector solenoid. Proceed to Test Step 8.

Test Step 7. Measure Solenoid Resistance at 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/RESET position.

2. Ensure that the J2/P2 ECM connector and the J52/P52 through J58/P58 unit injector connectors are disconnected.

3. Measure the solenoid resistance between terminals 1 and 2 and between terminals 3 and 4 at the J52 through J58 unit injector connectors. Record the measured resistance for each solenoid.

Expected Result:

Resistance should be between 0.6 and 3.6 Ohms for each solenoid.

Results:

• OK -

  Repair: Reconnect all connectors and repeat the Injector Solenoid Test. If the problem still exists, the ECM has a faulty injector driver. Replace the ECM. Refer to Troubleshooting, "Replacing the ECM" for the correct procedure.

  Stop.

• Not OK - There is a problem with the valve cover base harness or the injector solenoid. Proceed to Test Step 8.

Test Step 8. Check Resistance at the Injector Solenoid

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

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

2. Remove the valve mechanism cover from the suspect cylinder.

3. Remove the harness yoke from the solenoid terminals.

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

5. Measure the resistance from either solenoid terminal to the unit injector body (metal). Record the resistance.

Expected Result:

Resistance between the two solenoid terminals should be between 0.6 and 3.6 Ohms.

Resistance from either solenoid terminal to the fuel injector body (metal) should be greater than 20,000 Ohms.

Results:

• OK - The injector solenoid is electrically OK. There is a problem in the valve cover base harness.

  Repair: Repair the circuit.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The injector solenoid has failed.

  Repair: Replace the injector. Refer to Disassembly and Assembly, "Unit Injector - Remove" for the correct procedure.Verify that the repair eliminates the problem.

  Stop.

Test Step 9. Perform the Cylinder Cutout Test

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

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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/RESET position.

2. Verify that the J2/P2 ECM connector and the J52/P52 through J58/P58 unit injector connectors are properly connected.

3. Turn the keyswitch to the ON position.

4. Start the engine.

5. When possible, apply a load to the engine. This will help to differentiate a weak cylinder or a dead cylinder.

6. Perform the Cylinder Cutout Test on Cat ET.

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

8. Disable the override. Repeat 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 a bad cylinder.

Results:

• OK - All cylinders (solenoids) are functioning properly. Stop.

• Not OK - A cylinder is malfunctioning. This indicates that there is a problem with an injector.

  Repair: Replace the injector. Refer to Disassembly and Assembly, "Unit Injector - Remove" for the correct procedure.Verify that the repair eliminates the problem.

  Stop.