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C-10, C-12, C-15 and C-16 Industrial Engines – Switch Circuits – Test

System Operation Description:

Use the following diagnostic procedures in order to diagnose problems with the switch circuits and repair the switch circuits that are shown in Table 1.

Illustration 1 g01080836

Terminal locations for ECM connector

Test Step 1. Check the Electrical Connectors and the Wiring

  1. Place the engine control in the OFF/RESET mode and thoroughly inspect the J61/P61 customer connector, and J1/P1 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 suspect switch circuits.
  1. Check the J61/P61 customer connector (allen head screw) for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.

    Check the ECM connector J1/P1 for the proper torque. Refer to Troubleshooting, “Electrical Connectors – Inspect” for details.

  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 are OK. Proceed to Test Step 2.

  • Not OK – Repair the wiring and connectors or replace the wiring or the connectors. Ensure that all of the seals are properly connected. Verify that the repair eliminates the problem.STOP

Test Step 2. Check the Circuit for a Short to Engine Ground or a Short to another Wire in the Harness

Table 1
Pin Locations for Switch    
Name of Switch     J61/P61 Connection     P1 Connection    
Starting aid override switch     38     22    
Maintenance clear switch     12     23    
Torque limit switch     2     40    
Remote shutdown switch     27     44    
Intermediate speed switch     28     45    
Overspeed verify switch     40     54    
PTO interrupt switch     19     41    
PTO enable switch     29     56    
PTO ramp up switch     30     58    
PTO ramp down switch     39     60    

Illustration 2 g00763614

Typical schematic
  1. Disconnect the J1/P1 ECM connector.
  1. Determine the correct P1 pin number for the suspect switch. Refer to Table 1 for pin locations.

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

  1. Measure the resistance from ECM connector P1 to every pin on ECM connector P1.
    1. Measure the resistance from ECM connector P1 to the ECM ground strap.

Expected Result:

Each resistance measurement is more than 20,000 Ohms.

Results:

  • OK – The resistance check does not indicate a short in the engine harness or a short to engine ground. Proceed to Test Step 3.

  • Not OK – A resistance measurement is less than 20,000 Ohms. The wire for the suspect switch is shorted in the engine harness or the wire for the suspect switch is shorted to engine ground.

    Repair: Repair the wire or replace the wire. Replace all wires to the original configuration. Verify that the repair eliminates the problem.

    STOP

Test Step 3. Check the Circuit for an Open

  1. Determine the correct P1 pin number for the suspect switch. Refer to Table 1 for pin locations.
  1. Connect a wire jumper between the ECM connector P1 and engine ground.

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

  1. Measure the resistance from the suspect switch to engine ground. Take the measurement from the side of the switch that is connected to the customer connector.
  1. Remove the wire jumper from ECM connector P1.

Expected Result:

The resistance is less than 5 Ohms.

Results:

  • OK – The resistance check does not indicate an open circuit in the engine harness. The wires between the ECM connector P1 and the suspect switch are OK. Proceed to Test Step 4.

  • Not OK – A resistance measurement is greater than 5 Ohms. The measurement indicates excessive resistance in the circuit or an open in the circuit.

    Repair: Repair the wires or replace the wires. Inspect the customer connector for damage. Replace all wires to the original configuration. Verify that the repair eliminates the problem.

    STOP

Test Step 4. Check the Switch for Proper Operation

  1. Turn the suspect switch to the open position or the OFF position.

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

    1. Measure the resistance from the suspect switch to the −Battery. Take the measurement from the side of the switch that is connected to the customer connector.
    1. Record the resistance measurement.
  1. Turn the suspect switch to the closed position or the ON position.

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

    1. Measure the resistance from the suspect switch to the −Battery. Take the measurement from the side of the switch that is connected to the customer connector.
    1. Record the resistance measurement.

Expected Result:

The resistance measures more than 20,000 Ohms when the suspect switch is in the open position (OFF position). The resistance measures less than 5 Ohms when the suspect switch is in the closed position (ON position).

Results:

  • OK – The resistance checks are correct. The switch is operating correctly. Proceed to Test Step 5.

  • Not OK – A resistance check is not correct. The suspect switch is not operating correctly.

    Repair: Verify that the wire from the switch to the −Battery has continuity to the −Battery. If the wire to the −Battery is OK, replace the suspect switch. Replace all wires to the original configuration. Verify that the repair eliminates the problem.

    STOP

Test Step 5. Check the Switch Circuit at the J1/P1 ECM Connector

  1. Determine the correct P1 pin number for the suspect switch. Refer to Table 1 for pin locations.
  1. Remove the wire for the suspect switch at ECM connector P1. Install a wire jumper with sockets on both ends into the socket for the suspect switch.
  1. Reconnect ECM connector J1/P1.
  1. Connect a wire jumper between the wire jumper that was installed for the suspect switch and the −Battery.
  1. Connect the Caterpillar Electronic Technician (ET) to the service tool connector.
  1. Place the engine control in the ON mode.
  1. Monitor the switch input on the Cat ET.
  1. Place the engine control in the OFF/RESET mode.

Expected Result:

The circuit operates correctly.

Results:

  • OK – The circuit operates correctly.

    Repair: The problem may be intermittent. If the problem is intermittent, perform the diagnostic functional test Troubleshooting, “Electrical Connectors – Inspect”.

    STOP

  • Not OK – The circuit does not operate correctly.

    Repair: Perform the following repair:

    1. Temporarily connect a test ECM.
    1. Remove all jumpers and reconnect all connectors.
    1. Recheck the system for active diagnostic codes.
    1. Repeat the test step.
    1. If the problem is resolved with the test ECM, reconnect the suspect ECM.
    1. If the problem returns with the suspect ECM, replace the ECM.
    1. Verify that the repair eliminates the problem.

    STOP