3500B Marine Engines Caterpillar

The Electronic Control Module (ECM) has the ability to automatically prelube the engine before cranking. This prelubrication may increase the life of certain engine parts. The ECM will prelube the engine, when the Engine Control Switch (ECS) is placed in the START position. The ECM will prelube the engine, when the Engine Control Switch (ECS) is placed in the AUTO position and the remote start/run/stop switch is closed. The length of time for the prelube cycle can be programmed by the customer. The prelube cycle will end when the prelube pressure switch closes or if the customer programmed time ends. The engine speed must equal zero rpm before the prelube will begin.

The prelube cycle has the following status codes: "OFF", "ON", "COMPLETED" and "DISABLED".

The "OFF" status is entered when the engine control is first powered up with the ECS in the STOP position.

The "ON" status is entered when the ECM is on with the ECS in the START position.

The "COMPLETED" status is entered when the engine prelube duration is reached or when the engine prelube pressure switch is activated.

The "DISABLED" status is entered when the engine prelube duration is programmed to 0.

The prelube function will be aborted when one of the following conditions occur:

• The prelube pressure switch is activated.

• The user defined engine prelube duration has been reached.

• The operator activates the prelube override switch.

When the ECM senses the ECS in the START position, the ECM will activate the sinking driver for the prelube pump. This input allows current to flow through the main prelube relay to the ECM. When the main prelube relay energizes, the normally open contacts of the main prelube relay close. This allows current to flow to the prelube relay. The normally open contacts of the prelube relay close. This allows current to flow to the prelube motor. The prelube motor activates the prelube pump. The prelube pump builds pressure in the prelube system. When the prelube pressure switch closes as a result of the increased pressure in the prelube system, the ECM input for the prelube pressure switch is taken low. The ECM then knows that the prelube pressure is adequate to prelube the engine. The ECM will begin the starting sequence.

Illustration 1	g00979679
Typical example

Test Step 1. Check for Connector Damage.

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

2. Turn the ECS to the OFF/RESET 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 2.25 ± 0.25 N·m (20 ± 2 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:

All connectors, pins, and sockets are completely coupled and/or inserted, and the harness and wiring should be free of corrosion, of abrasion or of pinch points.

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 the Resistance of the Prelube Pressure Switch at the ECM.

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

2. Disconnect ECM connector J1/P1.

3. Ensure that the prelube override switch is not activated.

4. Measure the resistance between the prelube pressure switch P1-20 and the digital return P1-29.

5. Reconnect the ECM connector P1.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Note: If the engine has been running, the residual oil pressure may be high enough to activate the prelube pressure switch. If the residual oil pressure is high, the resistance would be less than 5 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. The prelube pressure switch is not active. Proceed to Test Step 4.

• Not OK - The resistance is less than 20,000 Ohms. The prelube pressure switch is active. Verify that the engine does not have a residual oil pressure that is high enough to activate the switch. If there is no residual oil pressure, the switch is not operating correctly or there is a problem with the wiring. Proceed to Test Step 3.

Test Step 3. Measure the Resistance of the Prelube Pressure Switch at the Prelube Pressure Switch.

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

2. Disconnect the wires from the terminals of the prelube pressure switch.

3. Measure the resistance between the terminals of the prelube pressure switch.

Expected Result:

The resistance should be greater than 20,000 Ohms.

Results:

• OK - The resistance is greater than 20,000 Ohms. There is a problem with the wiring between ECM connector J1/P1 and the switch.

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

  STOP

• Not OK - The resistance is less than 20,000 Ohms. There is a problem with the prelube pressure switch.

  Repair: Temporarily replace the prelube pressure switch with a new switch. If the problem is no longer present, reinstall the old switch. If the problem returns, replace the switch.

  STOP

Test Step 4. Check the Status of the ECS and the Prelube Pressure Switch on the Caterpillar Electronic Technician (ET).

1. Use the Cat ET and view the following parameters: Engine Prelube and Ignition Switch.

2. Turn the ECS to the STOP position.

3. View the parameters for the prelube pressure switch and the ignition switch.

4. Connect the Cat ET to the service tool connector.

5. Go to the diagnostic test in the diagnostic section on the CAT ET. Activate the override for the engine prelube.

6. View the parameters for the prelube pressure switch and the ignition switch.

7. Disable the override for the engine prelube.

Expected Result:

When the ECS is in the STOP position, the engine prelube should display "OFF" and the ignition switch should display "STOP". When the override for the engine prelube is activated, the engine prelube should display "ON" and the ignition switch should display "STOP".

Results:

• OK - The parameters are correct. Proceed to Test Step 5.

• Not OK - The status of the ignition switch does not display "STOP".

  Repair: Perform the diagnostic functional test Troubleshooting, "Engine Control Switch (ECS)".

  STOP

• Prelube Disabled - The prelube function is disabled. The engine prelube duration is set to zero.

  Repair: The cycle time of the engine prelube must be greater than zero for the prelube function to work.

  STOP

Test Step 5. Check for Output Voltage to the Prelube Motor from the Prelube Relay.

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

2. Connect one end of the voltmeter to the − Battery terminal.

3. Connect the other end of the voltmeter to wire C465-OR(Orange) on terminal 2 of the prelube relay.

4. Turn the ECS to the STOP position.

5. Go to the diagnostic test in the diagnostic section on the CAT ET. Activate the override for the engine prelube.

6. Monitor the voltage on the voltmeter.

7. Disable the override for the engine prelube.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 11.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 6.

Test Step 6. Check for Output Voltage to the Prelube Relay from the Main Prelube Relay.

1. Leave one end of the voltmeter on the − Battery terminal.

2. Connect the other end of the voltmeter to wire 118-GN(Green) on terminal 30 of the main prelube relay.

3. Turn the ECS to the STOP position.

4. Go to the diagnostic test in the diagnostic section on the CAT ET. Activate the override for the engine prelube.

5. Monitor the voltage on the voltmeter.

6. Disable the override for the engine prelube.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 7.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 8.

Test Step 7. Check the Voltage to the Coil of the Prelube Relay at the Prelube Relay.

1. Leave one end of the voltmeter on the − Battery terminal.

2. Connect the other end of the voltmeter to wire 118-GN(Green) on terminal 4 of the prelube relay.

3. Turn the ECS to the STOP position.

4. Go to the diagnostic test in the diagnostic section on the CAT ET. Activate the override for the engine prelube.

5. Monitor the voltage on the voltmeter.

6. Disable the override for the engine prelube.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC.

  Repair: Verify that 24 ± 3 VDC is present on terminal 1 of the prelube relay. If voltage is not present on terminal 1 of the prelube relay, check the wiring and circuit breakers between the prelube relay and the battery.

  Verify that the wire 200-BK(Black) on terminal 3 of the prelube relay has continuity to the − Battery terminal. If the wire 200-BK(Black) is okay and voltage is present on terminal 1 of the prelube relay, replace the prelube relay.

  STOP

• Not OK - The voltage does not measure 24 ± 3 VDC.

  Repair: Repair the wire 118-GN(Green) between the main prelube relay and the prelube relay.

  STOP

Test Step 8. Check the Voltage through the Coil of the Main Prelube Relay.

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

2. Remove the wire F705-PK(Pink) from terminal 86 of the main prelube relay.

3. Leave one end of the voltmeter on the − Battery terminal.

4. Connect the other end of the voltmeter to terminal 86 on the main prelube relay.

5. Turn the ECS to the STOP position.

6. Monitor the voltage on the voltmeter.

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

8. Reconnect the wire F705-PK(Pink) to terminal 86 of the main prelube relay.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. Proceed to Test Step 10.

• Not OK - The voltage does not measure 24 ± 3 VDC. Proceed to Test Step 9.

Test Step 9. Check the Battery Voltage to the Coil of the Main Prelube Relay.

1. Turn the ECS to the STOP position.

2. Leave one end of the voltmeter on the − Battery terminal.

3. Measure the voltage between wire 104-RD(Red) on terminal 85 of the main prelube relay and the − Battery terminal.

4. Measure the voltage between wire 104-RD(Red) on terminal 87 of the main prelube relay and the − Battery terminal.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. The problem is the main prelube relay.

  Repair: Replace the main prelube relay. Verify that the problem is no longer present.

  STOP

• Not OK - The voltage does not measure 24 ± 3 VDC. There is a problem in the wiring and/or connectors between the main prelube relay and the battery.

  Repair: Verify that the breaker for the relay is not tripped. Verify that the breaker for the battery is not tripped. Repair the connectors or wiring and/or replace the connectors or wiring.

  STOP

Test Step 10. Check the Sinking Driver on the ECM.

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

2. Disconnect ECM connector J1/P1.

3. Remove the wire F705-PK(Pink) from P1-21 at ECM connector P1. Install a wire jumper into P1-21.

4. Connect a voltmeter between the wire jumper in P1-21 and the − Battery terminal.

5. Turn the ECS to the STOP position.

6. Go to the diagnostic test in the diagnostic section on the CAT ET. Activate the override for the engine prelube.

7. Monitor the voltage on the voltmeter.

8. Disable the override for the engine prelube.

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

10. Remove all jumpers and replace all wires.

Expected Result:

The voltage should measure 24 ± 3 VDC.

Results:

• OK - The voltage measures 24 ± 3 VDC. There is a problem in the wiring between the ECM and the main prelube relay.

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

  STOP

• Not OK - The voltage does not measure 24 ± 3 VDC.

  Repair: Replace the ECM. Refer to the diagnostic procedure Troubleshooting, "Replacing the ECM".

  STOP

Test Step 11. Check the Operation of the Prelube Motor.

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

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

3. Connect one side of a suitable piece of 10 AWG wire to the + Battery terminal.

4. For one second, connect the other end of the wire to the + Battery terminal of the prelube motor.

Expected Result:

The prelube motor should start.

Results:

• OK - The prelube motor starts. There is a problem in the wiring harness between the prelube motor and the prelube relay.

  Repair: Inspect the connectors and the wiring between the positive terminal of the prelube motor and pin 2 of the prelube relay.

  STOP

• Not OK - The prelube motor did not start. The problem appears to be in the prelube motor.

  Repair: Replace the prelube motor with a new prelube motor. Verify that the problem is no longer present.

  STOP