Hyundai HL955 Manual page 380

2. TROUBLESHOOTING 2. TROUBLESHOOTING
1) 1) SERVICE BRAKE SERVICE BRAKE
Diagnose malfunction charts are arranged from most probable and simplest to verify, to least likely,
more difficult to verify. Remember the following steps when troubleshooting a problem :
Step 1. Operational check out procedure (see section 1)
Step 2. Operational checks (in this group)
Step 3. Troubleshooting
Step 4. Tests and adjustments (see group 3)
Problem
Poor or no brakes Poor or no brakes
Aggressive brakes Aggressive brakes
Brakes drag Brakes drag
Brakes lock up Brakes lock up
Cause
Brake accumulator charge low.
Brake pump standby pressure
low.
Brake pressure low.
Air in system.
Worn brake surface material.
Leakage in brake valve.
Leakage in brake piston seal.
Internal restriction in circuit.
Brake valve malfunction.
Low oil level.
Brake pedal not retur ning
properly.
Debris holding valve partially
open in brake valve.
Warped brake disk.
Stuck brake piston.
Brake valve malfunction.
4-37
Remedy
Do brake accumulator check.
Do brake pump standby pressure test.
Do brake valve pressure test.
Bleed brakes.
Inspect brake surface material.
Do brake valve leakage test.
Check for an over filled differential.
Apply brakes and check for leakage from check
plug.
※It is normal for the oil level to be slightly
above the check plug.
Remove lines and components.
Disassemble and inspect.
Check oil level.
Inspect floor mat and pedal.
Do brake valve pressure test.
Inspect brake disk.
Repair.
Clean or replace brake valve.