A Low Brake Pressure Warning Occurs When Brakes Are Applied; The Differential Pressure Warning Circuit Is Not Operating - Komatsu 930E-2 Shop Manual

POSSIBLE CAUSES
TROUBLE: Differential Pressure Warning Circuit activates Briefly When Brakes are Applied or Released
Brake valve out of balance (not tracking).
Differential pressure switch is defective or improperly
adjusted.
Accumulator precharge/leak.
Problem in brake valve subassembly.
Dual relay valve defective
Air in one brake circuit.
Small leak in one circuit.
Brake warning delay timer defective
Adjust collars according to instructions.
TROUBLE: A Low Brake Pressure Warning Occurs When Brakes are Applied
Leak or other malfunction in one brake circuit.
Brake valve balance is out of adjustment.
Differential pressure switch is defective or improperly
adjusted.
A dual relay valve is defective
TROUBLE: The Differential Pressure Warning Circuit is not Operating
Low Brake Pressure lamp is burned out.
Electrical problem.
Differential pressure switch is defective or improperly
adjusted.
Problem in brake valve assembly.
Dual relay valve defective
Brake warning relay defective.
J4-10
SUGGESTED CORRECTIVE ACTION
Check the switch and replace if defective.
Check differential pressure switch adjustment. Refer
to Table I - Differential Pressure Switch Adjustment.
NOTE: If the differential pressure switch is O.K. and
the differential pressure is 300 ±30 psi (2 068 ±207
kPa), replace "red" spring in Differential Pressure
Switch Assembly with "green" spring and re-adjust
differential pressure to: 600 ±50 psi (4 137 ±345 kPa).
Check accumulators and recharge if necessary.
Remove, disassemble, clean, and inspect brake valve
assembly or replace it.
Inspect and repair dual relay valve(s)
Bleed brakes.
Inspect brake system and repair leaks.
Replace timer.
Inspect brake system and repair leaks.
Adjust collars according to instructions.
Check the switch and replace if defective.
Check differential pressure switch adjustment. Refer
to Table I - Differential Pressure Switch Adjustment.
See NOTE: above.
Inspect and repair dual relay valve(s)
Replace bulb.
Check switch circuit wiring.
Check the switch and replace if defective.
Check differential pressure switch adjustment. Refer
to Table I - Differential Pressure Switch Adjustment.
See NOTE: above.
Remove, disassemble, clean, and inspect, or replace
brake valve.
Inspect and repair dual relay valve(s)
Replace relay.
Brake Circuit Checkout J04025