PROBLEM 12
No boom/mast hoist operation.
POSSIBLE CAUSES
Boom/mast hoist brake not releasing; Boom/mast hoist pawl not released or hung up; No voltage through control
handle to controller; No voltage out of controller to pump EDC; Wiring or switch is damaged.
CHECKS
On Diagnostic screen is drum brake disengaged when handle is moved in problem direction?
Does Diagnostic screen indicate a problem with pump, motor, brake, or pawl?
Yes No
Is drum brake switch in correct position?
Engine loads when moving problem handle in either direction?
Yes No
Yes
No
Move switch to correct position.
Is 28 volts present at brake solenoid when problem
handle is moved? (See Section 3 -Checking
Electrical Inputs/Outputs.)
Yes
No
Repair or replace wiring.
When moving problem handle fully in both directions, does Diagnostic
screen monitor show 100% handle command in each direction?
Yes
No
Yes
No
Yes No
Yes
No
Yes No
Yes
No
Yes No
Yes
No
Yes No
When moving problem handle fully in both directions,
does Diagnostic screen show 100% pump control in
each direction?
Is voltage at handle more than 0 with
handle moved? (See Section 3 -
Diagnostic Screen.)
Is pressure at brake 300 psi (21
bar) or more?
Correct problem.
Is there a system fault?
Repair or replace brake.
Readjust charge pressure
relief or replace pump.
Is system charge pressure
300 psi (21 bar) or more?
Replace brake valve.
Replace pump EDC.
Manually stroke pump. (See Section 2 - Manual Override Test.) Does pump pressurize?
Is voltage present at pump EDC? (See Section 3 -
Checking Electrical Inputs/Outputs.)
Repair or replace wiring.
Isolate pump. Does manually stroked
pump pressurize?
Repair or replace
motor.
Repair or replace
pump.
Is control handle center switch zero?
Yes
No
Consult dealer.
Consult Manitowoc dealer or
Crane Care Lattice Team.
Consult Manitowoc dealer or
Crane Care Lattice Team.
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