Cranking Circuit

1
Light Weight Fairway Mower
Electrical System
2
LWFM Slide Index
(Left Click Selection Box)
Cranking Circuit-Off Seat
Primary Run
Cranking Circuit-On Seat
Mow Circuit
Control Module
Backlapping Circuit
Run Circuit-Off Seat
Raise Lift Arms
Run Circuit-Off Seat/Backlap
Control Module Decal
Normal Run
High Power Accessories
3
Objectives

• Using an Electrical Schematic, Describe the
  Current Flow through the On-Board Diagnostic
  Module
• Name the Final LED Light that MUST be
  Illuminated for the Engine to Crank
• Name the Final LED Light that MUST be
  Illuminated for the Engine to Run

4
The battery provides current to the following
components regardless of ignition switch
position. 1- Starter Motor, 2-Ignition Switch,
3-Starter Relay 4-High Current Relay The
battery POS cable is connected to the high
current side of the starter solenoid. Two fusible
links attached to the same terminal, carry
current to the unswitched side of the ignition
switch, starter relay and high current
relay. With the ignition switch in the START
position, current flows to the high current
relay, energizing it. With the high current relay
energized, current flows from the battery through
the contacts in the relay, a 10 Amp fuse the
transmission neutral switch (in NEUTRAL), the
brake pedal switch (Brake applied), the
mow/transport switch (in Transport) and energizes
the starter relay. The ground wire for the
starter relay, goes through a diode, the ignition
switch (in START) and then to ground. With the
starter relay energized, current flows from the
battery, through the contacts in the relay, to
the starter solenoid energizing it. With the
starter solenoid energized, current flows from
the battery through the contacts in the solenoid
to turn the starter motor.
5
Cranking Circuit

• Off Seat

-
H
C
P
F
6
With the ignition switch in the START position,
current flows to the high current relay,
energizing it. With the high current relay
energized, current flows from the battery through
the contacts in the relay, a 10 Amp fuse the
transmission neutral switch (in NEUTRAL), the
seat switch and seat relay (Operator on seat),
the mow/transport switch (in Transport) and
energizes the starter relay. The ground wire for
the starter relay, goes through a diode, the
ignition switch (in START) and then to ground.
With the starter relay energized, current flows
from the battery through the contacts in the
relay, to the starter solenoid energizing it.
With the starter solenoid energized, current
flows from the battery through the contacts in
the solenoid to turn the starter motor.
7
Cranking Circuit
186BLK
735PUR/BLK

• On Seat

210RED
Ignition Switch
START
RUN
OFF
Fusible Link
225RED
High Current
Relay
221RED/WHT
Seat Relay
223RED/WHT
Start Relay
10AmpFuse
Mow/
SeatSwitch
Pos
NeutralSwitch
Transport
Battery
747PUR
OFF
TRANS

ON
Mow
Starter
IN GEAR
-
NEUTRAL
Neg
Battery
Diode Pack
Cable
Control Module
J3C
J2G
J3A
J1J
H
C
P
F
8
As you have seen in the previous schematic, each
terminal entering/exiting the control module is
identified with a J1, 2 or 3 prefix and then a
number and letter. The module has 3 connectors
where the wiring harness attaches. 1. J1
connector has 10 terminals. It is located on the
bottom of the module as the module is mounted on
the machine. 2. J2 connector has 8 terminal. It
is located on the top 3. J3 connector has 6
terminals, it is located in the middle. The
suffix of the terminal identifier 1. The
number corresponds to the individual pin (the
male end of the connector) in each of the group
of connectors. This number is printed on the
circuit board of the control module and is easily
visible when looking into the module with the
connector removed. 2. The letter corresponds to
connecting plug at the end of the wiring harness
(the female end of the connector). This system
of terminal identification makes both the wiring
harness and control module easier to diagnose
with a multi-meter should a problem occur
9
Control Module
J2
4
5
8 Pins
1
8
6 Pins
J3
3
4
1
6
J1
6
5
10 Pins
10
1

• Pin Locations

10
With the ignition switch in the RUN position,
current flows to and energizes the high current
relay. With the high current relay energized,
current flows from the battery through the main
contacts in the relay, to the 10 Amp fuse. From
the fuse to the park lock switch (Off), the seat
switch (operator on seat),then to seat relay and
into the control module. Current entering J1-G
lights LED N turns on a transistor inside the
control module, providing a ground for the
internal ignition/hold relay and inside the
module. Now current standing by at terminal J3-C,
indicated by the illumination of LED H, energizes
the internal ignition/hold relay, and the
internal pull-in coil relay. LED B will light
when the internal ignition/hold relay is
energized. LED G will light when the internal
pull-in coil relay is energized. Pull-in current
for the fuel shutoff solenoid comes from the main
contacts of the high current relay through the
main contacts of the pull-in coil relay.
11
Normal Run

• On Seat

C
N
H
B
12
Mow Circuit

• Lets Think About This!

• Where Have We Seenthe B Light CircuitBefore?
• Lets First Display the Normal Run Circuit

13
This part of the schematic performs the
identical task as it did in the Normal Run
Circuit slide shown previously. It is drawn
differently here simply to make room to show the
portion of the schematic that is responsible for
supplying current to the mow valves. 1. Current
flows through the 10 AMP fuse, illuminates H
light, and continues to make current available at
the hold in relay contacts and coil. At the same
time current flows through the park lock switch,
park OFF (this would illuminate C light, but
that is NOT shown on this slide) and the seat
switch, on seat, illuminating N light. This
energizes the transistor completing a path to
ground allowing the hold-in relay coil to
energize completing a current path out to the
injection pump fuel shut-off solenoid (Hold
windings). Just like we discussed earlier, BUT
what wasnt mentioned was this is also the
CURRENT SOURCE that provides electrical power to
the reel circuit. If THIS CIRCUIT IS NOT
SATISFIED, there will NOT be any current supplied
to power the reels.
14
Mow Circuit
10 Amp Fuse
ParkLock

• Fuel Shut-OffPortion

ON
OFF
Seat Switch
ON
OFF
H
N
.5 SecondDelayBreak
FuelShutoffSolenoid
B
15
Lets continue to build the reel circuit. 1. From
the same source that keeps the hold-in coil of
the fuel shut-off solenoid energized, current is
feed through the brake switch (brake off) and
illuminates S light making current available at
the mow enable relay contacts NOTE Point out
that when the brake pedal is depressed the reels
stop rotating! This switch controls that. 2.
Next the Mow/Trans lever must be moved into the
Mow position. This current illuminates J
light, energizes the enable relay and current
flows to the latch relay contacts and the
Raise/Lower switch. 3. Only when the
Raise/Lower lever is pushed forward (engaging
the switch) is current feed to the trigger relay.
Both K and M light are illuminated. Current
flows through the trigger relay, through the 1/2
second delay and energizes the transistor
providing a path to ground energizing the mow
latch relay. 4. At the same time, current through
the relay contacts goes to energize its coil
providing a latch 5. With the mow latch relay
energized, current flows across the relay
contacts, back to provide power to its own coil
and at the same time out across the service relay
contacts (relay NOT energized) out to the mow
valve solenoids.
16
Mow Circuit
S
H
N

• A-Trigger Latch Relay
• B-Ignition Hold Relay
• C-Mow Latch Relay
• D-Service Mow Relay
• E-Mow Enable Relay

A
E
C
B
D
E
B
17
Mow Circuit
S
H
N
J
A
E
A-Trigger Latch Relay B-Ignition Hold
Relay C-Mow Latch Relay D-Service Mow
Relay E-Mow Enable Relay
C
B
D
E
B
18
--We should now be able to recognize the safety
circuit current path through the the neutral and
brakes switches. 1. If the transmission is in
neutral and the brake switch is ON, current is
available to the service switch and F light
is illuminated. 2. With the service switch in the
service position, current flows into the control
box at J1-E, illuminates L light, energizes the
service relay coil and makes current available at
the contacts of the mow enable relay. The rest
of the circuit other than the path through the
service relay is the same as the normal Mow
Circuit. Follow the path through the trigger
and latch relays NOTE This source of current
(instead of through B light circuit via the
brake switch) and the service relay position are
the only two differences between the Mow
Circuit and this circuit. The service relay
gives an alternate path of current (Vs the Mow
Circuit) through the backlap switches allowing
the technician to turn either circuit ON or
OFF with the backlap pull out knobs. The .5
Second delay in this MOW circuit allows the
cutting units to run an additional 1/2 second
assuring that all the grass will be ejected
before the rotation stops when lifting.
19
Backlapping Circuit
H
J
C
L
F
A
D
Control Module RelaysA-Trigger LatchB-Mow
LatchC-Service MowD-Mow Enable
C
B
A