JLG 150HAX Service Manual - Manual (Page 132)

SECTION 6 - SCHEMATICS
6-4 – JLG Lift – 3120817
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Table 6-2.Boom Assembly - Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY
BOOM ELEVATION SYSTEM.
No response to lift control switch.
Lift control inoperative. Repair or replace control lever.
Dump valve (bypass) not operating. Determine cause and repair or replace valve.
Hydraulic system oil low. Replenish oil as necessary.
Restricted or broken supply line on valve bank or
hydraulic pump. Clean or replace line.
Control valve not functioning properly. Repair or replace valve.
Lift cylinder not functioning properly. Repair or replace cylinder.
Hydraulic pump not functioning properly. Repair or replace pump.
Boom will not raise.
Load capacity exceeded (personnel or equip-
ment on platform). Reduce load. (Refer to capacity placard.)
Hydraulic system oil low. Replenish oil as necessary.
Restricted or broken hydraulic line or fitting. Clean, repair, or replace line or fitting.
Control valve not functioning properly. Repair or replace valve.
Pressure relief valve not functioning properly. Re-adjust or replace valve.
Bypass valve (dump) not functioning. Repair or replace valve.
Lift cylinder not functioning properly. Repair or replace cylinder.
Contaminated port relief. Repair or replace valve.
Boom will not lower.
See: Boom will not raise