LAMP AS-INDICATOR 4215575 - Caterpillar

Personal injury or death can result from escaping fluid under pressure.Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue, causing serious injury, and possible death.Always use a board or cardboard when checking for a leak.Do not check for pin hole leaks in pump or motor hoses during a steer stall condition. If fluid is injected into your skin, it must be treated by a doctor familiar with this type of injury immediately.
Personal injury or death can result from sudden machine movement.Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine.To help prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic and steering system:
The pilot oil system supplies oil to the pilot control valve. The pilot control valve allows pilot oil to shift the main control valve spools.
Table 1
Required Tools    
Part Number     Description    
1U-5481     Pressure Gauge Group    
1U-5482     Pressure Adapter Group    Machine Preparation
Park the machine on a smooth, level surface. Park the machine in an area away from working machines and personnel.
Allow only one operator on the machine. Keep all personnel away from the machine and in the view of the operator.
Engage the parking brake. Lower the blade to the ground. Shift the machine into neutral.
Illustration 1 g00849168
Install the steering frame lock.
Release the hydraulic pressure in the machine. Push down on the service brake pedal several times. This will release any hydraulic pressure in the accumulators. Move all the hydraulic control levers in order to release the pressure in the hydraulic system. In order to relieve any pressure in the hydraulic oil tank, slowly remove the hydraulic tank cap.
Illustration 2 g00853451
Location of Pressure Tap For Pilot Pressure
Install 1U-5481 Pressure Gauge Group and 1U-5482 Pressure Adapter Group to the pressure tap.Note: The pressure tap is located next to the combination valve. The pressure tap is located on the right side of the machine. Access to the pressure tap can be gained by raising the cover on the platform over the hydraulic tank.
Engage the parking brake.
Shift the transmission to neutral.Testing Procedure
Start the engine. Warm the hydraulic oil to a normal operating temperature of approximately 49 to 65°C (120 to 150°F).
Run the engine at low idle. Observe the pressure gauge.
The pilot oil pressure should be 2400 100 kPa (350 15 psi) at a flow of 16 L/min (4.2 US gpm).
If the pilot pressure is incorrect, the setting of the pilot relief valve may require adjustment.
Stop the engine. Repeat step 5 in order to release hydraulic pressure. Disconnect the test equipment.Reference: For additional information on adjusting the pilot relief valve, refer to the Service Manual module Testing and Adjusting, "Relief Valve (Braking System Backup) - Test and Adjust" for the machine that is being serviced.