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 are the following displayed:
Boom down limit fault
Boom hoist pump - raise, no increase in system pressure
Boom hoist drum pawl in fault
Yes
No
Out In
Yes No
Yes
No
Yes
No
On boom hoist screen, is boom hoist pawl out when
moving brake park switch?
Check for problem. Repair limit
switch or wiring.
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?
Are 24 volts present (full speed) at pump EDC
when control handle is moved forward? (See
Section 3 - Checking Electrical Inputs/Outputs.)
Consult dealer/factory.
Repair or replace wiring or consult dealer/factory.
Replace pump EDC.
Repair or replace pump.
Can boom pump be manually stroked down?
(See Section 2 -Manual Override Test.)
When moving boom 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