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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. |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products. Dispose of all fluids according to local regulations and mandates. |
This section provides probable causes to known problems. Since there may be several probable causes, specific inspections or instrument tests may be recommended. These inspections and tests will help to identify the causes that are most probable.
Note: Make sure that you use an oil with the correct viscosity for the operating conditions.
Reference: For additional information about the various lubricant viscosities, refer to Operation and Maintenance Manual, "Lubricant Viscosities (Fluids Recommendations)" for your machine.
Problem List
The Accumulator Pressure Will Not Reach Cutout Pressure At Low Idle.
Probable Cause
Note: Low accumulator pressure typically causes a warning category 3 to occur. Low accumulator pressure may also engage the parking brake.
- When the hydraulic oil is hot and the engine is at low idle, pump output is not sufficient to overcome internal losses in the pump.
The Front Service Brakes Do Not Operate, And The Warning System Is Not Activated
Probable causes
- The brake group within the axle housing is damaged.
- The lines to the front service brakes are obstructed.
- The wiring harness connecting the service brake control valve to the ECM may be disconnected. The open condition could be the result of a loose connection or a broken wire inside the wiring harness.
The Rear Service Brakes Do Not Operate, And The Warning System Is Not Activated
Probable causes
- The brake group within the axle housing is damaged.
- The lines to the rear service brakes are obstructed.
- The wiring harness connecting the service brake control valve to the ECM may be disconnected. The open condition could be the result of a loose connection or a broken wire inside the wiring harness.
Service Brakes Slip, And The Warning System Is Not Activated
Probable causes
- One or both axles contain an incorrect hydraulic oil additive, or an incorrect quantity.
- The brake disc in the axle housing is worn.
The Service Brakes Are Not Applied Evenly
Probable causes
- The brake disc and associated components in the axle housing are excessively worn.
- The brake valve is sticking because of contaminated oil.
- The service brake valve is not delivering the correct amount of pressure.
- One accumulator is not holding the correct pressure. Incorrect pressure may be caused by a damaged piston seal.
Too Much Force Needed To Push The Brake Pedals, And The Warning System Is Not Activated
Probable causes
- The brake pedals and/or brake pedal linkages are damaged.
- The brake valve is sticking because of contaminated oil.
The Parking Brake Does Not Hold The Machine Stationary
Probable causes
- The parking brake must be adjusted.
- The brake linings are excessively worn.
- There is grease or oil on the brake drum and/or on the brake lining.
The Parking Brake Does Not Engage When The Parking Brake Switch Is Activated
Probable causes
- The parking brake solenoid is not functioning.
- The parking brake is out of adjustment.
- Parking brake switch or wiring is damaged. The damage could have resulted in an open or a short being created in the circuit. A continuity check of the wire will reveal the most likely problem.
The Low Oil Pressure Warning Will Not Turn Off
Probable causes
- There is inadequate pump pressure for the brake system.
- The hydraulic oil is too hot.
- Accumulator pressure sensor is malfunctioning or wiring is damaged.