October 2008 "3072ES / 3772ES / 3772ES HD" Service & Parts Manual
Page 4-2
GENERAL TROUBLESHOOTING TIPS
The 3072ES and 3772ES Aerial Work Platforms operate on a "Motor Control" theory in which fluid
flow volume is controlled by varying the speed of the DC electric motor. 100% of the fluid produced by
the pump goes to the selected function.
Battery Charge State
Before you begin troubleshooting this model, check the battery state of charge and inspect the bat-
tery connections for looseness or corrosion. A fully charged battery pack on a 48 Volts DC system will
have a nominal voltage of 52.5–54 Volts DC.
Common Causes of Electrical System Malfunctions:
• Battery switch is turned OFF (located to the left of lower controls).
• Battery connections are loose or corroded
• Battery is not fully charged.
• Emergency Stop buttons are pushed (OFF position).
• Circuit breaker is in the tripped (OFF position).
Common Causes of Hydraulic System Malfunctions:
• Hydraulic fluid level is too low.
• Incompatible hydraulic fluids mixed, destroying the additives and causing varnish build up,
resulting in the valves sticking.
• Water in the hydraulic fluid due to a damp climate.
• Improper hydraulic fluid used. Viscosity too high in cold climates. Viscosity too low in warm
climates.
• Hydraulic fluid contaminated with debris - filter change interval neglected.
NOTES: ISO Grade 32 hydraulic fluid, is a multiple viscosity fluid that is light
enough for cold climates and resists thinning in warm climates. Only
ISO Grade 32 or equivalent must be used.
Contamination always causes failure in any hydraulic system. It is very
important to be careful not to introduce any contamination into hydraulic
system during the assembly procedures. Please make sure all ports
and cavities of the manifold and cylinders are properly covered/plugged
during maintenance activities.
Refer to the accompanying illustrations when using the Troubleshooting Guide.
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