Komatsu 830E Shop Manual page 369

POSSIBLE CAUSES
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 "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.
TROUBLE: Oil is Leaking Around the Pedal Base
Defective seal on top of brake valve.
TROUBLE: The Pump Cycles Too Often Or Low Pressure Warning Comes On At Low Engine RPM
Excessive internal leakage in a component.
Accumulator precharge too high or too low.
Brake Valve plumbed incorrectly.
Internal leakage in brake valve assembly.
Pump is worn.
TROUBLE: The Pump Cycles Too Often Or Low Pressure Warning Comes On At Low Engine RPM
Leak in charge system.
Accumulators precharge too high or too low.
Brake Valve plumbed incorrectly.
Internal leakage in brake valve assembly.
Pump is worn.
J04031
SUGGESTED CORRECTIVE ACTION
Check wiring.
Replace the switch.
Check steering circuit pressures.
Rebuild or replace pump.
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.
Replace the seal.
Check all steering and brake system components.
Check accumulator precharge.
Correct plumbing.
Replace brake valve assembly.
Rebuild or replace pump.
Check charge system.
Check accumulator precharge.
Correct plumbing.
Replace brake valve assembly.
Rebuild or replace pump.
Brake Circuit Check-Out Procedure J4-9