525D, 535D, 545D and 555D Wheel Skidders Caterpillar

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Personal injury or death can result from sudden machine movement. Sudden movement of the machine can cause injury to persons on or near the machine. To prevent injury or death, make sure that the area around the machine is clear of personnel and obstructions before operating the machine.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Escaping fluid under pressure, even a pinhole size leak, can penetrate body tissue, causing serious injury, and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

Operator Keypad

The eight button keypad provides inputs to the Machine ECM for several features, these being as follows: Differential Locking, Lights, Operator Present Override, Implement Lockout, Lockup Clutch, and Parking Brake.

Illustration 1	g03682573
(1) Lockup clutch (2) Park Brake (3) Operator Present Override (4) Implement Lockout (5) Front Light (6) Rear Lights (7) Differential Lock Front (8) Differential Lock Rear

Buttons 7 and 8 operate the front and rear differential locks respectively. The center indicators to the left of each button illuminate when the differential lock is engaged.

If communication between the Machine ECM and the keypad is lost, the Machine ECM will return inputs from the keypad to their default states and one of the following diagnostics will be issued:

Troubleshooting Problem List

• There is constant noise in the differential.

• Noise occurs in the differential at different intervals.

• Noise only occurs during turns.

• Lubricant is leaking.

• The drive wheels do not turn but the universal joint turns.

Troubleshooting

Check for any active service codes from the machine electronic control. Solve any active service codes from the machine electronic control. Use the built-in electrical diagnostics that are performed with the Monitoring System and with the electronic control module.

Note: This machine is equipped with an electronic control module (ECM). The Machine ECM has a built-in diagnostic system that detects faults in the electronic system of the power train.

Reference: For additional information on troubleshooting the Machine ECM, refer to Service Manual, "Electronic Transmission Control System" for diagnostic procedures on the machine electronic control .

Reference: For additional information on troubleshooting the Machine ECM, refer to Service Manual, " Monitoring System" for diagnostic procedures.

Probable Causes of Problems in the Differential and Final Drive

The problem indicates that there is constant noise in the differential.

The probable causes include the following items:

1. The level of lubricant is incorrectly high or low.

2. The wrong type of lubricant is being used.

3. Wheel bearings are damaged or improperly adjusted.

4. The ring gear and the pinion do not have correct tooth contact.

5. The ring gear and the pinion are damaged or worn.

6. There is too much pinion to gear backlash or too little pinion to gear backlash.

7. Pinion bearings are loose or worn.

8. Side bearings are loose or worn.

The problem indicates that noise occurs in the differential at different intervals.

The probable causes include the following items:

1. Ring gear does not run evenly because the bolts on the ring gear are not tight or the ring gear is warped.

2. Differential bearings are loose or broken.

The problem indicates that noise only occurs during turns.

The probable causes include the following items:

1. Differential pinion gears are too tight on the retainer pins or on the pinion shaft.

2. Side gears are too tight in the differential case.

3. Differential pinion gears or side gears are faulty.

4. Thrust washers are damaged or worn.

5. There is too much backlash between the side gears and the pinion gears.

The problem indicates that the lubricant is leaking.

The probable causes include the following items:

1. Loss of lubricant through the axle shafts can be caused by any of the following conditions:

   1. Lubricant is above the proper level.

   2. The wrong type of lubricant is being used.

   3. There is a restriction in the axle housing breather.

   4. An oil seal for the axle shaft is worn or an oil seal was incorrectly installed.

2. Loss of lubricant at the pinion shaft can be caused by the following conditions:

   1. Lubricant is above the proper level.

   2. The wrong type of lubricant is being used.

   3. There is a restriction in the axle housing breather.

   4. An oil seal on the pinion shaft is worn or installed incorrectly.

   5. A universal joint flange is loose on the pinion shaft.

The problem indicates that the drive wheels do not turn but the universal joint turns.

The probable causes include the following items:

1. An axle shaft is broken.

2. Ring gear teeth are damaged.

3. The side gear or the differential pinion is broken.

4. The differential pinion shaft or the retainer pin is broken.