The Low Pressure Warning Circuit Not Operating Properly; Low Pressure Warning Is On Even Though System Pressure Is Proper; Low Pressure Warning Comes On And Pressure Is Low; A Brake Accumulator Bleeds Off Quickly When Supply Pressure Is Cut Off - Komatsu 930E-2 Shop Manual

POSSIBLE CAUSES
TROUBLE: The Low Pressure Warning Circuit Not Operating Properly
The Low Brake Pressure lamp is burned out.
The electrical circuit is open.
Pressure switch defective.
TROUBLE: Low Pressure Warning is On Even Though System Pressure is Proper
Short in electrical system.
Pressure switch is defective.
TROUBLE: Low Pressure Warning Comes On and Pressure is Low
Steering circuit is malfunctioning.
The pump is worn.
TROUBLE: A Brake Accumulator Bleeds Off Quickly When Supply Pressure is Cut Off
Accumulator bleeddown valve is open.
Accumulator precharge is low.
Leak in one circuit.
Malfunction in brake valve.
TROUBLE: A "Squeal" is Heard When Controller is Operated
Rapid operation of controller.
Brake Valve assembly is damaged.
Hydraulic oil is too hot.
TROUBLE: The Output Pressure At Controller is Correct but Brakes are Not Applying
Brake lines are blocked or improperly connected.
TROUBLE: The Brake Pressures Drift Excessively While Pedal is Held Steady
Contamination in brake valve assembly.
Damage in brake valve assembly.
Dual relay valve malfunctioning
J04025
SUGGESTED CORRECTIVE ACTION
Replace the bulb.
Check switch circuit wiring.
Replace the pressure switch.
Check wiring.
Replace the switch.
Check steering circuit pressures.
Rebuild or replace pump.
Close valve, check precharge.
Recharge accumulator
Check plumbing.
Remove, disassemble, clean, reassemble; or replace.
Normal
Replace the brake valve assembly.
Check entire hydraulic system for restriction etc.
Check plumbing.
Remove, disassemble, clean, reassemble; or replace.
Repair or replace brake valve assembly.
Repair or replace dual relay valve assembly.
Brake Circuit Checkout J4-11