HUB 3P6123 - Caterpillar

Illustration 1 g01276102
Typical schematic
Illustration 2 g01276103
Connector for the user interface panel to the ECM (Terminal 10) Return for the air shutoff (Terminal 11) Air shutoff
Illustration 3 g01276105
AC-C1 connector (Terminal 11) Air shutoff (Terminal 12) Return for the air shutoff
Illustration 4 g01276104
P2 ECM connector (P2-13) Air shutoff (P2-23) Return for the air shutoffTest Step 1. Inspect Electrical Connectors and Wiring
Turn the local/remote switch on the control panel to the OFF/RESET position.
Thoroughly inspect the ECM connectors. Inspect all of the other connectors for the circuit. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector that are associated with the circuit.
Check the ECM connector (allen head screw) for the proper torque. Refer to Troubleshooting, "Inspecting Electrical Connectors" for details.
Check the harness and the wiring for abrasion and for pinch points.Expected Result:All connectors, pins, and sockets are completely coupled and/or inserted. 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 in the 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.STOPTest Step 2. Test the Air Shutoff System
Turn the local/remote switch on the control panel to the LOCAL position.
Proceed to the "Diagnostic Overrides" screen on Cat ET. Activate the "overspeed verify override".
Start the engine.
Monitor the air shutoff solenoid as the engine speed nears the modified setpoint for overspeed.Note: As the engine speed exceeds the modified setpoint the air shutoff solenoid should activate. The engine should shut down.Expected Result:The air shutoff solenoid activates.Results:
OK - The air shutoff solenoid activated correctly.Repair: The problem may be intermittent. If the problem is intermittent, refer to the diagnostic functional test Troubleshooting, "Inspecting Electrical Connectors".STOP
Not OK - The air shutoff solenoid failed to activate. Proceed to Test Step 3.Test Step 3. Check the Voltage to the Air Shutoff Solenoid from the User Interface Panel
Turn the local/remote switch on the control panel to the OFF/RESET position.
Remove wire N757-GY from terminal TB85 or from terminal AC-C1-11 in the user interface panel. Refer to Illustration 1 in order to identify the configuration of the wiring.
Connect a voltmeter between the wire N757-GY and engine ground.
Turn the local/remote switch on the control panel to the LOCAL position.
Proceed to the "Diagnostic Overrides" screen on Cat ET. Activate the "overspeed verify override".
Start the engine.
Monitor the voltage on the voltmeter as the engine speed nears the modified setpoint for overspeed.Note: As the engine speed exceeds the modified setpoint the voltage should measure approximately 24 VDC for one second.
Turn the local/remote switch on the control panel to the OFF/RESET position.
Reinstall all wires.Expected Result:The voltage measured approximately 24 VDC.Results:
OK - The voltage was OK.Repair: Verify that wire G971-GY has continuity between terminal TBX07 and ECM connector P2-23 or between terminal AC-C1-12 and ECM connector P2-23. If wire G971-GY is OK, repair