SPOOL AS 9U8668 - Caterpillar

Probable Causes
Machine security system (if equipped)
Battery cables and/or batteries
Starting motor solenoid or starting circuit
Starting motor and/or flywheel ring gear
Electrical power supply
Internal engine faultRecommended Repairs
Machine Security System (If Equipped)
Verify that the correct ignition key is being used. Turn the keyswitch to the ON position.
Use the electronic service tool in order to check if diagnostic code 1639-09 is active. Verify that the lamp for the machine security system is on.
If diagnostic code 1639-09 is active, the machine security system is armed. Deactivate the machine security system and try to start the engine.
If the engine will not start, use the electronic service tool to check for logged diagnostic codes.
Make repairs for all diagnostic codes. Ensure that the repair has eliminated the fault.
If there are no active diagnostic codes, refer to the Troubleshooting Manual for your machine application. Battery Cables and/or Batteries
Inspect the main power switch, battery posts, and battery cables for loose connections and corrosion. If the battery cables are corroded, remove the battery cables and clean the battery cables. Clean the battery posts. Replace the cables. Tighten any loose connections.
Inspect the batteries.
Charge the batteries.
Load test the batteries. Refer to Systems Operation, Testing and Adjusting, "Battery - Test". Starting Motor Solenoid or Starting Circuit
Test the operation of the starting motor solenoid. Refer to Systems Operation, Testing and Adjusting, "Electric Starting System - Test".
Check the wiring to the starting motor solenoid. Starting Motor and/or Flywheel Ring Gear
Test the operation of the starting motor. Check the wiring for the starting motor. Refer to Systems Operation, Testing and Adjusting, "Electric Starting System - Test".
Inspect the pinion on the starting motor and the flywheel ring gear for damage. Electrical Power Supply
If there is no electrical power supply, investigate the cause and rectify any defects. Refer to Systems Operation, Testing and Adjusting, "Charging System - Test".Internal Engine Fault
Remove the glow plugs. Refer to Disassembly and Assembly, "Glow Plugs - Remove and Install".
Attempt to rotate the crankshaft through 360 degrees in both direction. If the crankshaft rotates correctly but fluid is expelled from the hole for the glow plug, investigate the cause of the fluid in the cylinder.
If the crankshaft rotates correctly and no fluid is expelled, install the glow plugs. Refer to Disassembly and Assembly, "Glow Plugs - Remove and Install".
If the engine does not rotate in Step 2, disassemble the engine. Refer to Disassembly and Assembly.
Inspect the internal components for the following conditions:
Seizure
Failure
Distortion