3412E, C30 and C32 Marine Engines Caterpillar

The engine synchronization switch may exhibit problems due to the following possibilities.

• Vessel Wiring

• Faulty Switch

• Electronic Control Module

• Faulty Display Indicator

Illustration 1	g00884187
Schematic

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the keyswitch OFF.

2. Thoroughly inspect the J3/P3 customer connector, the J1/P1 ECM connector, and the J2/P2 ECM connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

3. Perform a 45 N (10 lb) pull test on each of the wires in the customer connector and the ECM connector that are associated with the engine synchronization switch. Refer to Illustration 1 for pin locations.

4. Check the J3/P3 customer connector (allen head screw) for the proper torque of 2.25 ± 0.25 N·m (20 ± 2 lb in).

   Check the ECM connector J1/P1 and J2/P2 for the proper torque of 2.25 N·m (55 lb in).

5. Check the harness and wiring for abrasions and for pinch points from the battery to the ECM.

6. Verify that the negative battery connections to the negative battery bus bar are installed properly.

   Note: All negative battery bus bars must be connected together for proper engine synchronization.

Expected Result:

All connections have been properly installed and no damage has been observed in the connections or the wiring.

Results:

• OK - Proceed to Test Step 2.

• Not OK -

  Repair: Make the necessary repairs to the connections or the wiring.Verify that the repair eliminates the problem.

  Stop.

Test Step 2. Check the Operation of the Throttle Position Sensor

1. Remove J3:34 Sync Switch Input 1 and J3:35 Sync Switch Input 2 from the J3 customer connector for the "PORT" ECM and the "STBD" ECM.

2. Connect Cat ET to the service tool connector.

3. Turn the keyswitch to the ON position.

4. Monitor the "Desired Engine Speed" on Cat ET for both engines. Move the throttle from the low idle position to the high idle position while the "Desired Engine Speed" is being monitored.

Expected Result:

The "Desired Engine Speed" for each engine should move independently of each other.

Results:

• OK - The "Desired Engine Speed" for both engines changes independently of each other.

  Repair: Set the "Desired Engine Speed" for each engine within 50 rpm of each other.

  Proceed to Test Step 3.

• Not OK - The "Desired Engine Speed" does not change independently of each other.

  Repair: Refer to Troubleshooting, "Throttle Position Sensor Circuit - Test" in order to locate the problem and make the necessary repairs.Verify that the repair eliminates the problem.

  Stop.

Test Step 3. Install a Jumper at the Customer Connector and Monitor the "Desired Engine Speed" While the Throttle for the PORT Engine is Moved.

1. Turn the keyswitch OFF.

2. Fabricate two jumper wires that will reach from the negative battery bus bar to the J3 customer connector for each engine.

3. Install a 9W-0844 Connection Socket on one end of each jumper wire and a connector that will connect to the negative battery bus bar on the opposite end of each jumper wire.

4. Connect one jumper wire from the negative battery bus bar to the pin J3:34 on the PORT connector and connect the other jumper from the negative battery bus bar to the pin J3:35 on the STBD connector. Refer to illustration 1 for pin locations.

5. Turn the keyswitch to the ON position.

6. Operate the throttle for the PORT engine and observe the "Desired Engine Speed" for each engine.

Expected Result:

The "Desired Engine Speed" for both the PORT and the STBD engines should be equal and the speeds should change equally while the throttle for the PORT engine is moved.

Results:

• OK - The "Desired Engine Speed" changes when the throttle is changed. Proceed to Test Step 4.

• Not OK - The "Desired Engine Speed" does not change equally. Proceed to Test Step 5.

Test Step 4. Install a Jumper at the Customer Connector and Monitor the "Desired Engine Speed" While the Throttle for the STBD Engine is Moved.

1. Turn the keyswitch OFF.

2. Fabricate two jumper wires that will reach from the negative battery bus bar to the J3 customer connector for each engine.

3. Install a 9W-0844 Connection Socket on one end of each jumper wire and a connector that will connect to the negative battery bus bar on the opposite end of each jumper wire.

4. Connect one jumper wire from the negative battery bus bar to the pin J3:35 on the PORT connector and connect the other jumper from the negative battery bus bar to the pin J3:34 on the STBD connector. Refer to illustration 1 for pin locations.

5. Turn the keyswitch to the ON position.

6. Operate the throttle for the STBD engine and observe the "Desired Engine Speed" for each engine.

Expected Result:

The "Desired Engine Speed" for both the PORT and STBD engines should be equal and the speeds should change equally while the throttle for the STBD engine is moved.

Results:

• OK - The "Desired Engine Speed" changes when the throttle is changed. Proceed to Test Step 7.

• Not OK - The "Desired Engine Speed" does not change equally. Proceed to Test Step 6.

Test Step 5. Check the Wiring Between the ECM for the PORT Engine and the Customer Connector

1. Turn the keyswitch OFF.

2. Connect an ohmmeter between the following pins:
   • P1:25 to J3:34

   • P1:2 to J3:35

Expected Result:

The resistance is less than 10 ohms.

Results:

• OK - The resistance is less than 10 ohms. Proceed to Test Step 6.

• Not OK - The resistance is greater than 10 ohms. This indicates an open circuit.

  Repair: Repair the wiring or replace the wiring.Verify that the repair eliminated the problem.

  Stop.

Test Step 6. Check the Wiring Between the ECM for the STBD Engine and the Customer Connector

1. Turn the keyswitch OFF.

2. Connect an ohmmeter between the following pins:
   • P1:25 to J3:34

   • P1:2 to J3:35

Expected Result:

The resistance is less than 10 ohms.

Results:

• OK - The resistance is less than 10 ohms. Proceed to Test Step 7.

• Not OK - The resistance is greater than 10 ohms. This indicates an open circuit.

  Repair: Repair the wiring or replace the wiring.Verify that the repair eliminated the problem.

  Stop.

Test Step 7. Check the Negative Battery Side of the Circuit that is Used for the Engine Synchronization Switch.

1. Measure the resistance between the negative battery connection at the switch and a connection for the negative battery bus bar that is known and in the same general location.

Expected Result:

The resistance is 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. An open circuit exists.

  Repair: Repair the wiring or replace the wiring.Verify that the repair eliminates the problem.

  Stop.

Test Step 8. Check the Switch

1. Install a 100 mm (4 inch) jumper across the switch contacts in order to short the switch.

2. Turn the keyswitch to the ON position.

3. Monitor the "Desired Engine Speeds" on Cat ET.

4. Operate the throttle for the STBD engine and observe the "Desired Engine Speed" for each engine.

Expected Result:

The jumper wire does not affect the "Desired Engine Speeds".

Results:

• OK - The "Desired Engine Speeds" did not change. Proceed to Test Step 9.

• Not OK - The "Desired Engine Speeds" changed. The switch is not working properly.

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

  Stop.

Test Step 9. Jumper the Switch and Check the Voltage

1. Turn the keyswitch OFF.

2. Connect a voltmeter. Place the positive probe on the pin for the J3 customer connector that is suspect. Place the negative probe on the connection for the negative battery bus bar.

3. Turn the keyswitch ON.

4. Measure the voltage.

Expected Result:

The voltage should be less than 0.9 VDC.

Results:

• OK - The voltage is less than 0.9 VDC. Proceed to Test Step 10.

• Not OK - The voltage is greater than 0.9 VDC.

  Repair: The negative battery connection is not proper at an unknown location. Locate the improper connection and make the necessary repairs.Verify that the repair eliminates the problem and also verify that the voltage is less than 0.9 VDC.

  Proceed to Test Step 10.

Test Step 10. Measure the Voltage at the ECM

1. Turn the keyswitch OFF.

2. Fabricate two jumper wires that will reach from the negative battery bus bar to the J1 ECM connector for each engine.

3. Install a 9W-0844 Connection Socket on one end of each jumper wire and a connector that will connect to the negative battery bus bar on the opposite end of each jumper wire.

4. Connect the jumper wire from the negative battery bus bar in the engine room to the suspect pin on the J1 ECM connector.

5. Turn the keyswitch to the ON position.

6. Connect the voltmeter between the suspect J1 pin and the negative battery.

7. Measure the voltage.

Expected Result:

The voltage should be less than 0.9 VDC.

Results:

• OK - The voltage is less than 0.9 VDC. The ECM is not reading the switch input.

  Repair: If the problem still exists, temporarily connect a test ECM. 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.Refer to Troubleshooting, "Replacing the ECM" for additional information.

  Stop.