PROBLEM 15
Boom will not boom down, but will boom up.
POSSIBLE CAUSES
Boom maximum down limit opened; Pawl engaged; Pump is damaged;
Block-up limit open; Control handle is worn; Speed encoder is damaged.
CHECKS
When applicable switch or handle is enabled is the following displayed:
Boom down limit fault.
Boom/mast hoist pump - raise, no increase in system pressure.
Boom/mast hoist drum pawl in fault.
Yes
No
Out In
Yes No
Yes
No
Yes
No
On boom/mast hoist screen, is boom/mast hoist pawl out
when moving brake park switch?
Check for problem. Repair limit
switch, wiring, or circuit breaker.
Visually check pawl.
Replace or repair pawl.
Repair or replace switch or
wiring to controller.
Does Diagnostic screen show 100% pump control with handle
moved fully forward?
Is 28 volts present (full speed) at pump EDC when
control handle is moved forward? (See Section 3 -
Checking Electrical Inputs/Outputs.)
Repair or replace wiring.
Replace pump EDC.
Repair or replace pump.
Can boom pump be manually stroked down?
(See Section 2 -Manual Override Test.)
When moving boom/mast hoist handle fully in forward directions, does Diagnostic screen show
100% handle command in lower direction?
Yes No
Replace control handle or
repair wiring.
Any of the above displayed
None of the above displayed
Consult Manitowoc dealer or
Crane Care Lattice Team.