JLG 340AJ Service Manual - Manual (Page 219)

SECTION 5 - HYDRAULICS
3121259 – JLG Lift – 5-61
Troubleshooting
This section provides general steps to follow if you observe
undesirable system conditions. Follow the steps listed until
you solve the problem. Some of the items are system specific.
We reference the section in this manual if more information is
available. Always observe the safety precautions listed in the
Introduction section and precautions related to your specific
equipment.
PRECAUTIONS
HIGH INLET VACUUM CAUSES CAVITATION WHICH CAN DAMAGE INTERNAL
PUMP COMPONENTS.
ESCAPING HYDRAULIC FLUID UNDER PRESSURE CAN HAVE SUFFICIENT FORCE
TO PENETRATE YOUR SKIN CAUSING SERIOUS INJURY AND/OR INFECTION.
RELIEVE PRESSURE IN THE SYSTEM BEFORE REMOVING HOSES, FITTINGS,
GAUGES, OR COMPONENTS. SEEK IMMEDIATE MEDICAL ATTENTION IF YOU
ARE CUT
UNINTENDED MOVEMENT OF THE MACHINE OR MECHANISM MAY CAUSE
INJURY TO THE TECHNICIAN OR BYSTANDERS. TO PROTECT AGAINST UNIN-
TENDED MOVEMENT, SECURE THE MACHINE OR DISABLE/ DISCONNECT THE
MECHANISM WHILE SERVICING.
CONTAMINATION CAN DAMAGE INTERNAL COMPONENTS AND VOID THE MAN-
UFACTURER'S WARRANTY. TAKE PRECAUTIONS TO ENSURE SYSTEM CLEANLI-
NESS WHEN REMOVING AND REINSTALLING SYSTEM COMPONENTS AND
LINES.
HYDRAULIC FLUID CONTAINS HAZARDOUS MATERIAL. AVOID CONTACT WITH
HYDRAULIC FLUID. ALWAYS DISPOSE OF USED HYDRAULIC FLUID ACCORDING
TO STATE, AND FEDERAL ENVIRONMENTAL REGULATIONS.
Table 5-10. Electrical Troubleshooting
Item Description Action
Control operates pump in one direction only. Control coil failure Measure resistance at coil pins. Resistance should be 14.20
Ohm (24V) or 3.66 Ohm (12V) at 20×C [70×F]. Replace
coil.
No pump function No power to controller Restore power to controller.
Erratic pump function Electrical connection to pump is bad Disconnect connection, check wires, reconnect wires.
Filter bypass indicator switch Filter switch may be bad Check/replace filter switch. Add gauge to filter bypass port
to verify proper fluid flow and verify switch operation by
measuring resistance, open resistance=>510 Ohm,
closed resistance<=122Ohm