CENTRAL AND LOWER STRUCTURE 6V6444 - Caterpillar

The connection of any electrical equipment and the disconnection of any electrical equipment may cause an explosion hazard which may result in injury or death. Do not connect any electrical equipment or disconnect any electrical equipment in an explosive atmosphere.
Probable Causes
Batteries
Battery cables
Starting circuit
Starting motor solenoid
Starting motor
Flywheel ring gear
Transmission (if applicable)
Engine accessories
Hydraulic cylinder lock
Internal engine problemRecommended Actions
Batteries and/or Battery Cables
Inspect the main power switch, 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". 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. Transmission (if applicable) or Engine Accessories
Ensure free movement of the driveline.
Remove any engine accessories that may lock up the engine and inspect any engine accessories that may lock up the engine. The following list illustrates examples of engine accessories that may lock up the engine:
Hydraulic pump that is driven from the rear gear group
Air compressor
Engine oil pump
Other components that are driven by the engineHydraulic 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 the Disassembly and Assembly manual. Inspect the internal components for the following conditions:
Seizure
Broken components
Bent components