Overview
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 of more information is available. Always observe the safety precautions listed in the
Introduction section and any precautions related to your specific equipment.
Safety precautions
Caution
High inlet vacuum causes cavitation which can damage internal pump components.
Warning
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.
Warning
Unintended movement of the machine or mechanism may cause injury to the technician or bystanders.
To protect against unintended movement, secure the machine or disable/disconnect the mechanism
while servicing.
Caution
Contamination can damage internal components and void the manufacturer’s warranty. Take
precautions to ensure system cleanliness when removing and reinstalling system lines
Warning
Hydraulic fluid contains hazardous material. Avoid contact with hydraulic fluid. Always dispose of used
hydraulic fluid according to state, and federal environmental regulations.
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 ohms (24V) or 3.66 ohms (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 ohms, closed resistance=122
ohms
Service Manual
MP1
Troubleshooting
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Danfoss | April 2019 AX00000244en-000201 | 43
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