C32 Marine Propulsion Engines Caterpillar


Switch Circuits - Test

Usage:

C32 RND
System Operation Description:

Switch circuits may have problems such as faulty wiring, faulty switches, or faulty connectors. Use the following diagnostic procedures in order to diagnose problems with these switch circuits and repair these switch circuits:

  • Maintenance clear switch

  • Remote engine stop switch

  • Slow vessel mode switch

  • Synchronize switch (No.1)

  • Synchronize switch (No.2)

  • Trip clear switch

  • Trolling mode switch

These switches are normally open or normally closed.




Illustration 1g01390154

Typical switch inputs and wiring

Test Step 1. Check the Electrical Connectors and the Wiring

  1. Remove the electrical power from the Electronic Control Module (ECM).



    Illustration 2g01377328

    Location of the connectors that are for the switch circuits (rear engine view)

    (1) J1/P1 ECM connectors

    (2) Customer connector

  1. Thoroughly inspect connectors (1) and (2). Thoroughly inspect the connections for the suspect switch. Refer to Troubleshooting, "Electrical Connectors - Inspect".



    Illustration 3g01378034

    Terminal locations at the J1/P1 ECM connectors that are for the switch circuits

    (P1-22) Remote engine stop switch

    (P1-23) Maintenance clear switch

    (P1-35) Synchronize switch (No.1)

    (P1-40) Trip clear switch

    (P1-41) Trolling mode switch

    (P1-44) Synchronize switch (No.2)

    (P1-59) Slow vessel mode switch




    Illustration 4g01369117

    Terminals at the customer connector that are for the switch circuits

    (Terminal 19) Trip clear switch

    (Terminal 34) Synchronize switch (No.1)

    (Terminal 35) Synchronize switch (No.2)

    (Terminal 36) Remote engine stop switch

    (Terminal 37) Trolling mode switch

    (Terminal 38) Slow vessel mode switch

    (Terminal 39) Maintenance clear switch

  1. Perform a 45 N (10 lb) pull test on each of the wires in the circuit for the suspect switch.

  1. Check the allen head screw on each ECM connector for the proper torque. Also, check the allen head screw on the customer connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.

  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 wiring and connectors appear to be OK. Proceed to Test Step 2.

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

    Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.

    STOP

Test Step 2. Test the Switch for Proper Operation

  1. Disconnect the P1 connector.

  1. Refer to Table 1. Determine the P1 terminal for the suspect switch.

    Table 1
    Terminals for the Switch Inputs    
    Name of the Switch     Terminal Locations at the J1/P1 ECM Connectors     Terminal Locations at the Customer Connector    
    Maintenance clear switch     23     39    
    Remote engine stop switch     22     36    
    Slow vessel mode switch     59     38    
    Synchronize switch (No.1)     35     34    
    Synchronize switch (No.2)     44     35    
    Trip clear switch     40     19    
    Trolling mode switch     41     37    

  1. Connect one lead of a multimeter to the P1 terminal for the suspect switch. Connect the other lead of the multimeter to negative ground.

    Note: Wiggle the harnesses during the following measurements in order to reveal any intermittent short condition.

  1. Measure the resistance between the P1 terminal for the suspect switch and negative ground.

  1. Activate the switch and measure the resistance again.

Expected Result:

One resistance measurement indicates an open circuit. The other resistance measurement indicates that a short circuit exists.

Results:

  • OK - One resistance measurement indicates an open circuit. The other resistance measurement indicates that a short circuit exists.

    Repair: The switch is operating correctly. The wiring does not have a short circuit or an open circuit. Operate the engine and check the switch for proper operation.If the switch does not operate correctly, there may be a short circuit between the circuit for the suspect switch and another circuit. Carefully reinspect the components. Refer to Troubleshooting, "Electrical Inspectors - Inspect". Locate the short circuit and perform repairs.

    STOP

  • Not OK - Both resistance measurements indicate an open circuit or both resistance measurements indicate a short circuit.

    Repair: There is a problem with the circuit for the switch. The problem could be in the switch, in the wiring, or in a connector.Carefully reinspect the components. Refer to Troubleshooting, "Electrical Inspectors - Inspect" for information that relates to troubleshooting suspect electrical problems in the harness.If the inspection does not identify the faulty component, replace the switch and test the switch again.If the problem is not resolved, repair the wiring or the connector. Replace parts, if necessary. Verify that the problem is resolved.

    STOP

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