Problem 12
No boom hoist operation.
POSSIBLE CAUSES
Boom hoist brake not releasing; Boom hoist pawl not released or hung up; No voltage through control handle to PC controller;
No voltage out of PC controller to pump EDC; Wiring or switch is defective.
CHECKS
Diagnostic display DRUM 4 screen (bank 4) displays 1 when control handle is moved in problem direction?
Yes No
Is drum brake switch in correct position?
Engine loads when moving problem handle in either direction?
Yes No
Yes
No
Consult dealer/factory. Move switch to correct position.
Use test plug adapter. (See Test 11.) Is 12
volts present at disc brake solenoid 82E
when problem handle is moved?
Yes No
Repair or replace wiring or switch.
Consult dealer/factory.
When moving problem handle in both directions, does DRUM 4
diagnostic screen (bank 1) obtain 100% handle control in each direction?
Yes No
Yes No
Yes
No
Yes
No
Yes
No
Yes No
Yes
No
Yes
No
Yes
No
Yes
No
Yes No
Yes
No
Does drum turn while moving
handle and actuating manual
override on brake valve?
When moving problem handle in both directions,
does DRUM 4 diagnostic screen (bank 2) obtain
100% pump control in each direction?
Is voltage at handle 82P more than
0 with handle moved? (See Test 7.)
Replace valve.
Is pressure at brake 300 psi or more?
Consult dealer/factory.
Correct problem.
Is there an operating or system fault?
Repair or replace brake.
Readjust charge pressure
relief or replace pump.
Is system pressure 300 psi or less?
Replace brake valve.
Replace pump EDC.
Manually stroke pump. (See Test 16.)
Does pump pressurize?
Use test plug adapter. (See Test 13.)
Is voltage present at pump EDC?
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.
Replace fuse F12 (87FA)
and/or wiring. (See Test 6.)
Is 10 volts at handle (87FA)?
Remove fuse F12 (87FA). Is 10
volts DC available at fuse holder
Repair or replace handle.
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