TM 9-4940-568-20
2-146
Table 2-21. Crane Troubleshooting (CONT).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
5. BOOM DOES NOT LOWER WITH REMOTE CONTROL (CONT).
Test 5.
Remove boom controller from remote control unit. Refer to paragraph 5-12 in this
manual. Place EMERGENCY STOP switch in ON position. Check for continuity
between the following locations:
From remote control cable connector
pin location:
To controller connector terminal
location:
Check 1
H
8D
Check 2
M
14
Check 3
B
2F
If no continuity is found, repair the wiring within the remote control unit. Refer to
paragraph 3-16 in this manual.
If continuity is found, go to Test 6.
Test 6.
Tag and mark connectors on boom controller switches. Remove the connectors
from the two controller switches. Check each switch for continuity between the
following switch terminal locations, with the controller lever in the position noted:
Switch Terminals:
Controller handle position:
Test results:
Check 1
NC to COM
Neutral
Continuity
Check 2
NO to COM
Neutral
No continuity (open)
Check 3
NC to COM
Full UP position
No continuity (open)
Check 4
NO to COM
Full UP position
Continuity
If the above test results are not obtained, replace switch(es). Refer to paragraph
5-12 in this manual.
If the above test results are obtained, reinstall the controller switch connectors and
go to Test 7.
