Defective relay in panel Check for 12 volts between relay pins #30
(hot) and #86 (ground). If voltage is 0, check
for voltage between pin #87a and ground. If
12 volt, replace relay (With no electrical
power to the relay, pins #30 and #87a
should show continuity. With 12 volts to
either #85 or #86 and the other grounded,
there should be continuity between pins #87
and #30.)
ANTI-TWO BLOCK SYSTEM FOR CRANES EQUIPPED WITH FUNCTION
DISCONNECTS ONLY. LIGHT AND HORN ARE ON, BUT CONTROLS WILL NOT
DISENGAGE
CAUSE REMEDY
Defective function disconnect Check voltage across disconnect terminals.
If 12 volts, check override key switch in
control panel. If 0 volts, repair or replace
disconnect. (Check other disconnects for
condition.) To operate the crane the solenoid
must have 12 volts supplied to one side and
have a good ground on the other side.
Under this condition, the disconnect should
act as a solid link. With the 12 volts
removed, the disconnect should allow free
motion of the control lever in one direction
and operate the valve spool in the other
direction.
Defective override key switch Check to insure that the switch is in the off
position and the key removed. Check for 12
volts in the control panel. If so, replace the
switch or control panel.
T300-1_T500-1_T780
Troubleshooting
430 P/N 12261-683
REVISED: January 2015
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