TROUBLESHOOTING 777 SERVICE MANUAL
10-2 Published 10-01-2012, Control # 045-08
• Use the standard test plug adapters (available from
MANITOWOC CRANES INC.) for electrical testing.
• Check ground potentials when testing electric circuits for
continuity, voltage, or resistance. When checking
voltages, use ground point for circuit being checked. If
voltage does not register on multi-meter, use a known
ground. If a value is read, the ground of the circuit under
test is probably faulty.
• Check all terminal points for cleanliness and tighten
connections.
• Check pressures at the specified hydraulic component
ports.
• Check the motor pressure control pilot (PCP) valve on
the motor under test. Test the pump electric
displacement controls (EDC) on the pump under test.
• Check each pressure sender electric supply at the
system sender.
• Check the encoder electric supply at the test plug
adapter of the encoder under test.
• Check the correct operating limit electric supply by
viewing the diagnostic display in the operator's cab.
• Check the control handle electrical input and output
voltages at the control handle under test.
• Check the basic system electric supplies and cab power
relay at the fuse box mounted above the main electrical
junction box in the operator’s cab.
• Check the programmable controller (PC) input and
output cables at the connector pins.
TEST EQUIPMENT
The test equipment shown or described is available for
testing the crane hydraulic or electrical systems. This
equipment can be purchased in kit form (with or without
carrying case) or separately, by contacting the factory Parts
Department.
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