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C9 Marine Auxiliary and Marine Generator Set Engines Caterpillar


Switch Circuits - Test

Usage:

C9 C9A
System Operation Description:

Use this procedure to troubleshoot any suspect problems with the switch inputs to the Electronic Control Module (ECM).

This troubleshooting procedure checks the following components if a problem is suspected.

  • Wiring

  • Switches

  • ECM

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Illustration 1g01173118

Schematic

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Illustration 2g01173384

P1 ECM connector

(P1-22) Emergency stop switch

(P1-23) Maintenance clear switch

(P1-40) Diagnostic reset switch

(P1-47) Low idle switch

Test Step 1. Inspect Electrical Connectors and Wiring

  1. Turn the keyswitch OFF.

  1. Thoroughly inspect the J61/P61 customer connector, the J1/P1 ECM connector, and the J2/P2 ECM connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.

  1. 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 diagnostic lamp. Refer to illustration 1.

  1. Check the J61/P61 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 6.0 N·m (55 lb in).

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

Expected Result:

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

Results:

  • OK - The connectors and wiring are OK. Proceed to Test Step 2.

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

    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. Verify the Negative Battery Connections

  1. Locate the negative battery bus bars and verify that the connections are installed properly.

    Refer to Troubleshooting, "Engine Wiring Information" for additional information.

Expected Result:

The negative battery connections have been properly installed.

Results:

  • Ok - The connections for the negative battery bus bar have been installed properly. Proceed to Test Step 3.

  • Not Ok - The connections for the negative battery bus bar have not been installed properly.

    Repair: Make the necessary connections in order to ensure proper installation.

    Proceed to Test Step 3.

Test Step 3. Check the Status of the Switch

  1. Connect the electronic service tool to the service tool connector.

  1. Turn the keyswitch to the ON position.

  1. Monitor the status screen on the electronic service tool while each switch is cycled.

Expected Result:

Each switch is displayed as "ON" and "OFF" when the switch is cycled.

Results:

  • OK - The switches are operating properly.STOP

  • Not OK - There is a problem with the wiring or the switch. Proceed to Test Step 4.

Test Step 4. Install a Jumper at the Customer Connector and Check the Status of the Switch

  1. Turn the keyswitch to the OFF position.

  1. Fabricate a jumper wire that will reach from the negative battery bus bar to the J61 customer connector.

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

  1. Connect the jumper wire from the negative battery bus bar to the pin for the suspect switch on the J61 customer connector.

  1. Turn the keyswitch ON.

  1. Monitor the status screen on the electronic service tool as the jumper wire is connected and disconnected from the customer connector.

Expected Result:

The status screen indicates a change in status for a particular switch.

Results:

  • OK - The status screen indicated a change in switch status. There is a problem in the circuit between the customer connector and the negative battery bus bar. Proceed to Test Step 5.

  • Not OK - The switch status on the status screen did not change. Proceed to Test Step 8.

Test Step 5. Bypass the Switch

  1. Make a jumper wire that is 100 mm (4 inch) long. Use two 9W-0852 Connector Pin on the ends of the wire.

  1. Turn the keyswitch to the OFF position.

  1. Install the jumper wire across the switch that is suspect.

  1. Turn the keyswitch ON.

  1. Monitor the status screen on the electronic service tool for the suspect switch.

Expected Result:

The switch status changes for the suspect switch.

Results:

  • OK - The switch status changed.

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

    STOP

  • Not OK - The switch status did not change. Proceed to Test Step 6.

Test Step 6. Check the Negative Battery Wiring for the Suspect Switch

  1. Turn the keyswitch OFF.

  1. Measure the resistance between the negative battery terminal on the suspect switch and a negative battery connection that is in close proximity. Check in order to ensure that the negative battery connection is good.

Expected Result:

The resistance is less than 5 Ohms.

Results:

  • OK - The resistance is less than 5 Ohms. The wiring is OK. Proceed to Test Step 7.

  • Not OK - The resistance is greater than 5 Ohms.

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

    STOP

Test Step 7. Measure the Voltage for the Suspect Switch at the Customer Connector

  1. Turn the keyswitch ON.

  1. Connect the positive probe of the voltmeter to the input for the suspect switch on the customer connector J61 and connect the negative probe of the voltmeter to the negative battery bus bar.

Expected Result:

The voltage is less than 0.9 VDC.

Results:

  • OK - The voltage is less than 0.9 VDC. The input signal is correct. Proceed to Test Step 8.

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

    Repair: Ensure that the negative battery connection to the switch is a direct connection to the negative battery bus bar in the engine room. If the voltage is fluctuating, the wire from the switch to the J61 customer connector is faulty.Replace the wire.Verify that the repair eliminates the problem.

    STOP

Test Step 8. Check for a Short between the Customer Connector and the ECM

  1. Turn the keyswitch OFF.

  1. Measure the resistance between the suspect switch input on the customer connector J61 and the negative battery terminal on the same connector.

    Wiggle the harness during the measurement. This will help reveal an intermittent condition.

Expected Result:

The resistance is greater than 5 Ohms.

Results:

  • OK - The resistance is greater than 5 Ohms. Proceed to Test Step 9.

  • Not OK - The resistance is less than 5 Ohms. The circuit is shorted to the negative battery.

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

    STOP

Test Step 9. Check for an Open Circuitbetween the Customer Connector and the ECM

  1. Disconnect the ECM connector P1 from the ECM.

  1. Measure the resistance between the input for the suspect switch on the customer connector J61 and the input for the suspect switch on the ECM connector P1.

Expected Result:

The resistance is less than 5 Ohms.

Results:

  • OK - The resistance is less than 5 Ohms. Proceed to Test Step 10.

  • Not OK - The resistance is greater than 5 Ohms.

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

    STOP

Test Step 10. Check the voltage at the ECM

  1. Turn the keyswitch to the OFF position.

  1. Install a 70-pin Breakout T at the J1/P1 ECM connector.

  1. Turn the keyswitch to the ON position.

  1. Measure the voltage between the input for the suspect switch and the negative battery.

Expected Result:

The voltage is less than 0.9 VDC.

Results:

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

    Repair: Perform the following procedure.

    1. Temporarily connect a test ECM.

    1. Cycle the suspect switch and monitor the switch status on the electronic service tool.

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

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

    STOP

  • Not OK - The voltage is correct. An intermittent condition exists. Repeat the test steps and carefully observe the connectors.STOP

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