725, 730 and 730 EJECTOR Articulated Trucks Power Train Caterpillar

Note: The troubleshooting information is intended to aid in diagnosing a given problem. The possible causes are ordered from the most probable cause to the least probable cause. The possible causes should be examined in order until the problem is resolved.

Refer to Systems Operation, Testing and Adjusting, "Machine Preparation for Troubleshooting" before you perform any testing and adjusting or troubleshooting.

Prior to carrying out troubleshooting on the interaxle differential lock, use Caterpillar ET in order to diagnose any fault codes that may be present. Refer to Systems Operation, Troubleshooting, Testing and Adjusting, RENR8085, "Power Train Electronic Control System".

If fault codes are present, repair the source of the fault code.

The Interaxle Differential Does Not Engage

Possible Cause

1. The hoses or the lines in the hydraulic system for the transfer gear and the differential locks may be damaged.
   • Inspect the condition of the lines. Refer to Systems Operation, Testing and Adjusting, "Visual Inspection".

2. The electrical circuit for the interaxle differential lock may have a blown fuse.
   • Check the circuit. If there is a blown fuse, replace the blown fuse. Refer to Operation and Maintenance Manual, SEBU7814, "Fuses - Replace" and Schematic, RENR8087, "Electrical Systems".

3. The oil supply to the solenoid and relief valve group may not be sufficient.
   • Test the oil supply to the solenoid and relief valve group. Refer to Systems Operation, Testing and Adjusting, "Interaxle Differential - Test".

4. The solenoid in the solenoid and relief valve is not functioning correctly.
   • Test the solenoid for correct operation. Refer to Systems Operation, Testing and Adjusting, "Interaxle Differential - Test".

5. The seals on the piston in the interaxle differential may be leaking.
   • The pressure of the oil in the interaxle differential may be lower than the specification. Check the pressure of the oil when the interaxle differential is selected. Refer to Systems Operation, Testing and Adjusting, "Power Train Pressures".

6. There is debris or damaged components in the interaxle differential or in the transfer gear.
   • Inspect the oil filter and inspect the magnetic screen for debris.

   • Determine the origin of the debris and repair or replace the damaged component.

   • Change the oil. Clean the magnetic screen and install a new oil filter.

7. The disks or plates of the interaxle differential may be worn or damaged.
   • Inspect the condition of the plates and disks in the interaxle differential. Replace the plates or the disks if the plates or the disks are damaged or worn. Refer to Disassembly and Assembly.

The Effort of Steering Increases With Load and/or The Interaxle Differential Does Not Disengage

Possible Cause

1. The solenoid in the solenoid and relief valve group may be sticking.
   • Check the operation of the solenoid. Refer to Systems Operation, Testing and Adjusting, "Interaxle Differetial - Test".

   • Check the pressure of the oil for the interaxle differential when the interaxle differential is unselected. Refer to Systems Operation, Testing and Adjusting, "Interaxle Differential - Test".

2. There is debris or damaged components in the interaxle differential or in the transfer gear.
   • Inspect the oil filter and inspect the magnetic screen for debris.

   • Determine the origin of the debris and repair or replace the damaged component.

   • Change the oil. Clean the magnetic screen and install an new oil filter.

3. The piston in the interaxle differential may be sticking.
   • Check the oil pressure in the interaxle differential when the interaxle differential is unselected. Refer to Systems Operation, Testing and Adjusting, "Power Train Pressures ". If the oil pressure is normal, the piston may be sticking. Inspect the lockup clutch for correct operation. Refer to Disassembly and Assembly, "Interaxle Differential - Disassemble ".