GEAR-PLANETARY 9G8638 - Caterpillar

Perform a visual inspection at the beginning of troubleshooting a problem. Perform the inspection while the engine is turned off. Put the transmission control in the NEUTRAL position.
Do not check for leaks with your hands. Pin hole (very small) leaks can result in a high velocity oil stream that will be invisible close to the hose. This oil can penetrate the skin and cause personal injury. Use cardboard or paper to locate pin hole leaks.
Check for leaks.Inspect all oil lines, hoses, and connections for damage or for leaks.Note: If oil can leak out of a fitting or a connection, air can leak into the system. Air in the system can be as bad as a low amount of oil.
Check the electrical system.Inspect the harnesses, the electrical connectors and the fuse for the ECM. Refer to Electrical Schematic, KENR5278 for the TA19.With the engine start switch and the battery disconnect switch in the OFF position, check the 20 ampere fuse for the Electronic Control Module. If the fuse is open, replace the fuse.Inspect the electrical harnesses for damaged wires or for broken wires. Disconnect each connector and look for pins and sockets that have been bent, broken, or removed. Look for any foreign material inside the connectors. The connectors must be tightened with normal force. The connectors must be disconnected with the same amount of force.Check the Electronic Control Module. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, KENR6678, "Power Train Electronic Control System".