3412E, C30 and C32 Marine Engines Caterpillar

The customer installed switches provide a path to ground for the respective switch circuit. A short to ground condition will cause the switch to be active. An open circuit in the wiring will prevent the switch from working properly.

The following tests check the following components if a problem is suspected.

• Wiring

• Faulty switch

• Electronic control module (ECM)

Illustration 1	g00884378
Schematic

Illustration 2	g00886448
P1 and P2 ECM connectors

Test Step 1. Inspect Electrical Connectors and Wiring

1. Turn the keyswitch to the OFF position.

2. Thoroughly inspect the J3/P3 customer connector and the J1/P1 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 switch circuits. Refer to Illustration 1.

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

   Check the J1/P1 ECM connector for the proper torque of 2.25 N·m (20 lb in).

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

6. Check for proper connections to the negative battery bus bar. Verify that the negative battery bus bar is connected to the negative terminal on the battery.

Results:

• OK - Proceed to Test Step 2.

• Not OK - There is a problem with the wiring or the connectors.

  Repair: Repair the connectors or wiring and/or replace the connectors or wiring. 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 the Status of the Switch

1. Connect the Caterpillar Electronic Technician (Cat ET) to the service tool connector.

2. Turn the keyswitch to the ON position.

3. Monitor the status screen on Cat ET while you cycle the suspect switch.

Expected Result:

The status for the suspect switch is displayed as "On" and "Off" when the switch is cycled.

Results:

• OK - The switches are operating properly. Stop.

• Status remains "ON" - There is a short circuit in the wiring between the ECM and the switch. Proceed to Test Step 7.

• Status remains "OFF" - There is an open circuit in the wiring or the switch. Proceed to Test Step 3.

Test Step 3. Check the Voltage at the Switch

1. Turn the keyswitch to the ON position.

2. Use a voltage test lamp between the two terminals of the suspect switch.

Expected Result:

The voltage test lamp should turn on.

Results:

• OK - The voltage test lamp turns on. The switch is receiving power. Proceed to Test Step 4.

• Not OK - The voltage test lamp did not turn on. The switch is not receiving power. Proceed to Test Step 5.

Test Step 4. Check the Switch

1. Turn the keyswitch to the ON position.

2. Use a voltage test lamp to check for voltage on the negative side of the switch. Connect one end of the voltage test lamp to the negative side of the switch. Connect the other end of the voltage test lamp to the negative battery bus bar.

3. Move the suspect switch to the ON position.

Expected Result:

The voltage test lamp should turn on when the switch is turned on.

Results:

• OK - The voltage test lamp turns on. The switch is OK.

  Repair: Repair the wiring between the switch and the negative battery.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The voltage test lamp does not turn on. The switch is bad.

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

  Stop.

Test Step 5. Check the Voltage at the Customer Connector

1. Remove the socket for the suspect switch from the P3 customer connector.

2. Turn the keyswitch to the ON position.

3. Connect one end of the voltage test lamp to the appropriate pin on the J3 customer connector. Connect the other end to the negative battery bus bar.

Expected Result:

The test lamp should turn on.

Results:

• OK - The test lamp turns on. There is a problem in the wiring between the customer connector and the switch.

  Repair: Repair the wiring between the customer connector and the switch.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The test lamp does not turn on. Proceed to Test Step 6.

Test Step 6. Check the Voltage at the ECM

1. Install a 40-Pin Breakout T between the J1 and P1 ECM connectors.

2. Connect one end of a voltage test lamp to the appropriate pin for the suspect switch on the breakout T. Connect the other end to terminal 5 (-Battery).

Expected Result:

The voltage test lamp should turn on.

Results:

• OK - The voltage test lamp turned on. There is a problem in the wiring between the ECM and the customer connector.

  Repair: Repair the wiring between the ECM and the customer connector.Reconnect the J1/P1 ECM connector.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The voltage test lamp did not turn on.

  Repair: Perform the following procedure.

  1. Temporarily connect a test ECM.

  2. Cycle the suspect switch while you monitor the switch status on Cat ET.

  3. If the problem is resolved with the test ECM, then reconnect the suspect ECM.

  4. If the problem returns with the suspect ECM, then replace the ECM.
  Refer to Troubleshooting, "Replacing the ECM" for additional information.

  Stop.

Test Step 7. Check the Circuit at the Customer Connector

1. Turn the keyswitch to the OFF position.

2. Remove the socket for the suspect switch from the P3 customer connector.

3. Turn the keyswitch to the ON position.

4. Observe the status of the suspect switch on Cat ET.

Expected Result:

The status of the suspect switch is "Off".

Results:

• OK - The status of the suspect switch is "Off". Proceed to Test Step 8.

• Not OK - The status of the suspect switch is "On". Proceed to Test Step 9.

Test Step 8. Check the Switch

1. Turn the keyswitch to the OFF position.

2. Disconnect the wire between the suspect switch and the J3/P3 customer connector at the switch.

3. Turn the keyswitch to the ON position.

4. Observe the status of the suspect switch on Cat ET.

Expected Result:

The status of the suspect switch is "Off".

Results:

• OK - The status of the suspect switch is "Off". The switch is bad.

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

  Stop.

• Not OK - The status of the suspect switch is "On". There is a short circuit in the wiring between the switch and the customer connector.

  Repair: Repair the wiring between the customer connector and the switch.Verify that the repair eliminates the problem.

  Stop.

Test Step 9. Check for a Short Circuit at the ECM

1. Turn the keyswitch to the OFF position.

2. Disconnect the wire for the suspect switch from the appropriate terminal on the P1 ECM connector. Leave the P1 ECM connector connected to the ECM.

3. Turn the keyswitch to the ON position.

4. Observe the status of the suspect switch on Cat ET.

Expected Result:

The status of the suspect switch is "Off".

Results:

• OK - The status of the suspect switch is "Off". There is a short circuit in the harness between the ECM and the customer connector.

  Repair: Repair the wiring between the ECM and the customer connector.Verify that the repair eliminates the problem.

  Stop.

• Not OK - The status of the suspect switch is "On".

  Repair: Perform the following procedure.

  1. Temporarily connect a test ECM.

  2. Cycle the suspect switch while you monitor the switch status on Cat ET.

  3. If the problem is resolved with the test ECM, then reconnect the suspect ECM.

  4. If the problem returns with the suspect ECM, then replace the ECM.
  Refer to Troubleshooting, "Replacing the ECM" for additional information.

  Stop.