Item Description Action
Servo pressure There is insufficient pressure differential across the
servo piston.
Check servo pressures at port M4 and M5 to verify
sufficient pressure delta. Verify that the servo supply
and drain paths are unobstructed and that each
orifice is of the correct size and free of debris. Clean,
repair, or replace as necessary.
Charge pump The charge pump has been damaged or installed
with the incorrect rotational orientation.
Verify that the charge pump is in good working order
and that it is correctly installed. Repair or replace it as
necessary.
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
Series 40 M46 Tandem Variable Pumps
Troubleshooting
18 |
©
Danfoss | September 2017 11029852 | AX00000030en-US0202
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