Manitowoc Published 10-01-2012, Control # 045-08 10-17
777 SERVICE MANUAL TROUBLESHOOTING
10
Problem 15
Boom will not boom up or boom down.
POSSIBLE CAUSES
Pump is damaged; Block-up limit opened;
Equalizer/boom stop limit opened; Control handle is damaged.
CHECKS
Check Diagnostic Screen D2. (See Diagnostic Display topic in Section 3.)
When applicable switch was enabled…
Bank 1 changed by 32 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Block-up limit
Bank 4 changed by 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rated capacity indicator/limiter
Bank number increased
by number shown.
Bank number not increased
by number shown.
Does diagnostic BOOM HOIST screen (bank 1) approach
+100% handle control with handle moved back?
Check for problem. Repair
limit switch, wiring, or fuse.
Yes No
Yes No
Yes No
Yes
No
Does diagnostic BOOM HOIST screen (bank 2) approach
+100% pump control with handle moved back?
Repair or replace control handle.
Use test plug adapter. (See Test 13.) Are -2.3 or more volts
present at pump EDC when control handle is moved back?
Consult dealer/factory.
Can boom pump be manually stroked down? (See Test 16.)
Repair or replace wiring or consult dealer/factory.
Replace pump EDC. Repair or replace pump.
When moving applicable handle fully in both directions, does A1
diagnostic screen (bank 3) read 38 to 120 in lower or 136 to 215 in raise?
Yes
No
Repair or replace control handle/wiring.
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