Manitowoc 999, Service And Maintenance Manual

Page: 261 / 298

Reference
Only
Manitowoc
Published 05-16-17, Control # 233-03
10-25
999 SERVICE/MAINTENANCE MANUAL TROUBLESHOOTING
10
CHECKS
Does system pressurize to 3,500 psi when moving mast switch to
raise position in operator cab?
Problem 22
Mast cylinders will not raise or lower.
POSSIBLE CAUSES
Not in setup mode; Faulty control valve section; Low pump pressure; Bad pump;
Switch failure; Faulty counterbalance valve.
Yes
No
Repair
problem.
Are mechanical problems present at
mast assist cylinders?
Yes No
See Diagnostic Display topic in section 3. Does (bank 1)
change by 32 for raise and (bank 2) change by 4 for lower when
moving mast switch from neutral to raise or lower?
Yes No
Adjust cylinder counterbalance
valve (See Test 26.) Does
cylinder operate correctly?
Replace cylinder or
consult dealer/factory.
No
Is crane setup mode selected and confirmed?
Yes No
Consult dealer/factory.
Select and confirm setup mode.
Check for 12 volts at mast power switch, pin number
WB-06 for raise or WB-11 for lower.
Voltage No Voltage
Are solenoids magnetized when
switch position is enabled?
Yes
No
Replace power switch fuse F4.
Replace solenoid valve.
Check diagnostic display DRUM 2 screen (bank 6)
for 350 psi charge pressure with handle in neutral.
Pressure Ok Pressure not Ok
Repair or replace
control valve.
Adjust rear drum charge pressure. (See Test 17.)
Repair or replace rear drum pump, if necessary.