PROBLEM 15
The boom will not boom down, but will boom up.
POSSIBLE CAUSES
The boom maximum down limit opened, the pawl engaged, the pump is damaged,
block-up limit open, the control handle is worn, the speed encoder is damaged.
CHECKS
When the 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 the boom/mast hoist screen, is the boom/mast hoist pawl
out when moving the brake park switch?
Check for the problem. Repair the limit
switch, wiring, or circuit breaker.
Visually check the pawl.
Replace or repair the pawl.
Repair or replace switch or
wiring to the controller.
Does the Diagnostic screen show 100% pump control with the
handle moved fully forward?
Are 28 volts present (full speed) at the pump EDC
when the control handle is moved forward? (See
Section 3 - Checking Electrical Inputs/Outputs.)
Repair or replace the wiring.
Replace the pump EDC.
Repair or replace the pump.
Can the boom pump be manually stroked down?
(See Section 2 -Manual Override Test.)
When moving the boom/mast hoist handle fully in the forward direction, does the Diagnostic screen
show 100% handle command in the lower direction?
Yes No
Replace the control handle or
repair the wiring.
Any of the Above Displayed
None of the Above Displayed
Consult your Manitowoc dealer or
the Crane Care Lattice Team.
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