Manitowoc 777

Reference Only
Manitowoc Published 10-01-2012, Control # 045-08 10-15
777 SERVICE MANUAL TROUBLESHOOTING
10
Problem 13
No boom cylinder operation.
POSSIBLE CAUSES
Boom hoist park switch (boom pump enable) not releasing; Boom cylinder hold switch or valve(s) damaged; No voltage
through control handle to PC controller; No voltage out of PC controller to pump EDC; Wiring or switch is damaged.
CHECKS
Diagnostic display BHST screen (bank 7) displays a value when control handle is moved in problem direction?
Yes No
Is boom hoist park (boom pump enable) switch in correct position?
Does engine load when moving problem handle in
either direction?
YesNo
Yes
No
Consult dealer/factory. Move switch to correct position.
Is boom cylinder hold switch in on position?
Yes
No
Place boom cylinder hold switch in
off position.
When moving problem handle in both directions, does BHST
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
When moving problem handle in both directions,
does BHST diagnostic screen (bank 2) obtain
100% pump control in each direction?
Is voltage at handle more than 0 with
handle moved? (See Test 7.)
Consult dealer/factory.
Correct problem.
Is there an operating or system fault?
Repair or replace boom cylinder
hold switch, wiring or 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 F11 (87FA)
and/or wiring. (See Test 6.)
Is 10 volts at handle (87FA)?
Remove fuse F11 (87FA). Is 10
volts DC available at fuse holder
Repair or replace handle.