PROBLEM 12
No boom hoist operation.
POSSIBLE CAUSES
Boom hoist brake is not releasing; boom 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?
Does engine load when moving problem handle in either direction?
Yes No
Yes
No
Consult dealer/factory.
Move switch to correct position.
Are 24 volts present at brake solenoid when problem
handle is moved?
(See Section 3 -Checking Electrical Inputs/Outputs.)
Yes
No
Repair or replace wiring or switch.
Consult dealer/factory.
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?
Consult dealer/factory.
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 or
consult dealer/factory.
Isolate pump. Does manually stroked
pump pressurize?
Repair or replace
motor.
Repair or replace
pump.
Consult factory/dealer.
Is control handle center switch zero?
Yes
No
Consult dealer/factory.
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