Textron Jacobsen Super LF 1880 Fairway Mower with ROPS, Service & Repair Instructions

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ELECTRICAL SYSTEM
10I-30
SOLENOIDS
While solenoids are similar to relays in construction,
solenoids have a different purpose. The solenoids
used in the LF-1880 electrical system when energized
create a magnetic draw, which seat and unseat a pop-
pet or plunger in the fuel or hydraulic system to allow
fluids to travel to and from a component. The fuel sole-
noid allows fuel to flow to the engine fuel system. The
hydraulic solenoids control the flow of hydraulic oil to
and from hydraulic components.
Figure 10I-3. Solenoid Circuit
One side of the solenoid coil is grounded. When cur-
rent is applied to the opposite side, a magnetic field is
generated within the coil (Figure 10G-3). This magnetic
field is used to move the poppet or plunger in the com-
ponent.
There are three basic tests that can be performed on
the solenoid to determine its condition.
• Power Inlet and Ground
• Coil Resistance
• Coil Operation
Testing power inlet and ground determines if current
from the electrical system is actually applied to the
solenoid and if the solenoid is grounded for proper
operation.
Testing coil resistance determines if the coil resistance
is too high to allow the flow of current.
If the other coil tests are satisfactory, the component
needs to be tested to determine if the fluid is present at
the solenoid and if the poppet or plunger is moving to
allow the fluid to flow through the component.
Use the electrical schematics in Section 10Q to find the
solenoid and the wiring harness connections to be
tested.
Use the hydraulic schematics in Section 8P and the
engine manufacturer’s manual to find the fluid flow
components.
FUEL SOLENOID TEST
When the ignition switch is placed in the START posi-
tion, the fuel solenoid plunger is drawn open allowing
fuel to flow to the engine fuel system.
CHECKING POWER INLET AND GROUND
1. Shut down the engine and remove the ignition
key. Allow the engine to cool completely.
2. Set the multimeter to 20 VDC range.
3. Disconnect wiring harness connector to the fuel
solenoid.
4. Connect black (NEG -) to the black wire terminal
in the wiring harness connector. Connect the red
(POS +) test lead to the brown wire terminal in the
wiring harness connector.
5. Hold the ignition switch in the START position.
Multimeter should read battery voltage; if battery
voltage is present the fuel solenoid may be faulty.
If low or no voltage registers, check for bad
grounds, high circuit resistance, opens, and a
faulty start relay (K20).
6. Connect black test lead to the black wire terminal
in the wiring harness connector. Connect the red
test lead to the brown wire terminal in the wiring
harness connector.
7. Place the ignition switch in the RUN position.
There should be no voltage reading on the multim-
eter.
If multimeter reads battery voltage, the start relay
(K20) may be faulty.
8. Connect the black test lead to the black wire termi-
nal in the wiring harness connector. Connect the
red test lead to the green/red wire terminal in the
wiring harness connector.
9. Hold the ignition switch in the START position.
There should be battery voltage reading on the
multimeter.
COIL RESISTANCE
1. Set the multimeter to 200
Ω
.
2. Connect the black test lead to the black wire termi-
nal (G) in the fuel solenoid connector. Connect the
red test lead to the brown (P) wire terminal in the
fuel solenoid connector.
Multimeter should read between 6.5 and 8.0
Ω
.
If multimeter is not within the above range, the coil
is faulty – replace coil.
If there is no multimeter reading, coil is faulty-
replace coil.
Gy/Rd
Bk
K12