HUB 7T9788 - Caterpillar

Probable Causes
Emergency stop switch
Batteries
Battery cables
Cranking circuit
Starting circuit
Starting motor solenoid
Starting motor
Flywheel ring gear
Engine accessories
Hydraulic cylinder lock
Internal engine problemRecommended Actions
Emergency Stop Switch
Verify that the emergency stop switch is in the RUN (out) position. If the switch is depressed, fuel injection is disabled and the engine will not be allowed to crank. Refer to the diagnostic functional test Troubleshooting, "Engine Shutdown Switch Circuit - Test".Batteries and/or Battery Cables
Inspect the battery posts, and battery cables for loose connections and for corrosion. If the battery cables are corroded, remove the battery cables and clean the battery cables. Tighten any loose connections.
Inspect the batteries.
Charge the batteries. Refer to Special Instruction, SEHS7633, "Battery Test Procedure".
Load test the batteries. Refer to Special Instruction, SEHS9249, "Use of 4C-4911 Battery Load Tester for 6, 8 and 12 Volt Lead Acid Batteries". Cranking Circuit
The Electronic Modular Control Panel (EMCP) controls the crank cycle for the engine. A crank relay is used to actuate the Starter Motor Magnetic Switch (SMMS) for the starter. Ensure that the cranking circuit is operating correctly. Perform the following Steps:
Check the output voltage of the crank relay at the EMCP.
Check if the SMMS is receiving the correct control coil voltage.
Check the input voltage for the secondary circuit of the SMMS.
Check the output voltage for the secondary circuit of the SMMS. The correct voltages during engine cranking will be equal to the battery voltage.If any of the voltages are incorrect, repair the circuit.Starting Motor Solenoid or Starting Circuit
Test the operation of the starting motor solenoid.
Check the wiring to the starting motor solenoid. Starting Motor or Flywheel Ring Gear
Test the operation of the starting motor.
Inspect the pinion for the starting motor and the flywheel ring gear for damage. Engine Accessories
Ensure free movement of the driveline.
Ensure that the timing pin was not left in the flywheel housing.
Remove any engine accessories that may lock up the engine and inspect any engine accessories that may lock up the engine. Hydraulic Cylinder Lock
Check for fluid in the cylinders (hydraulic cylinder lock) by removing the individual unit injectors.Note: Drain the fuel from the cylinder head. Fuel will flow from the cylinder head into the cylinders when the unit injector is removed.Internal Engine Problem
Disassemble the engine. Refer to Disassembly and Assembly.
Inspect the internal components for the following conditions:
Seizure
Broken components
Bent components