4
4241262-Rev B 4-1
Chapter 4
Electrical
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Test and Adjustment Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Repair Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Theory and Diagnostic Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Electrical Component Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Electrical Schematic Component Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7
Electrical Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Theory of Operation and Sub-Circuit Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Power Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Diesel Engine Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
Diesel Engine Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Raise/Lower Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19
Raise Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20
Lower Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22
Mow Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-25
Mow Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-26
Traction Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-29
Traction Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-30
Backlap Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-33
Backlap Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-34
Horn and Work Lights Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-37
Horn and Work Lights Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-38
Instrumentation Circuit—Theory of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-41
Instrumentation Circuit Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-42
Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-44
LCD Maintenance Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-44
Basic LCD System Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-45
System Diagnostic Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-54
Power Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-58
Horn Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-58
Work Light Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-58
Glow Plug Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-59
Start Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-59
Charging Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-60
Raise/Lower Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-60
Mow Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-61
Instrumentation Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-61
4-2 4241262-Rev B
ELECTRICAL
4
Component Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-63
Electrical System and Component Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-63
50A Circuit Breaker Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-64
Fuses Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-64
Relays Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-65
Key Switch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-65
Mow Switch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-66
Rocker Switches Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-66
Horn Switch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-67
Backlap Switch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-67
Raise/Lower Switch Assembly Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-68
Seat Switch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-69
Hydraulic Oil Level Switch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-70
Solenoids Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-71
Traction Solenoid Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-71
Fuel Shutoff Solenoid Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-72
Traction Pedal Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-73
Reel Level Proximity Switch Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-73
Repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-75
Front Cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-75
MCU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-75
Battery and Battery Tray . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-76
Alternator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-77
Starter Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-77
Armrest Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-78
Instrument Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-78
LCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-80
Rocker Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-80
Key Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-81
Raise/Lower Switch Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-82
Reel Level Proximity Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-82
Backlap Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-83
12V Accessory Socket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-84
12V Accessory Socket Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-84
MCU Fuses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-85
50A Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-85
Start Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-86
Glow Plug Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4-86
Traction Pedal Position Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-87
Engine Oil Pressure Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-88
Engine Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-88
Hydraulic Oil Level Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-89
Hydraulic Filter Pressure Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-90
Solenoids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-91
Brake Solenoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-92
Fuel Shutoff Solenoid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-93
Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-93
ELECTRICAL
4241262-Rev B 4-3
4
Specifications
Test and Adjustment Specifications
Repair Specifications
Specification
Resistance Across Solenoid Coil—
Front Mow Solenoid Coil at 68° F
ohms 5.3 ± 10%
Resistance Across Solenoid Coil—
Front Backlap Coil at 68° F
ohms 5.3 ± 10%
Resistance Across Solenoid Coil—
Rear Mow Solenoid Coil at 68° F
ohms 5.3 ± 10%
Resistance Across Solenoid Coil—
Rear Backlap Coil at 68° F
ohms 5.3 ± 10%
Resistance Across Solenoid Coil—
Raise Solenoid Coil at 68° F
ohms 5.3 ± 10%
Resistance Across Solenoid Coil—
Lower Solenoid Coil at 68° F
ohms 5.3 ± 10%
Resistance Across Solenoid Coil—
Brake Solenoid Coil at 68° F
ohms 9 ± 10%
Resistance Across Solenoid Coil—
Traction Solenoid Coil at 75° F
ohms 23
Resistance Across Fuel Shutoff Pull-In Coil at 68° F
ohm 0.5 ± 10%
Resistance Across Fuel Shutoff Hold-In Coil at 68° F
ohms 15 ± 10%
Traction Pedal Adjustment Value 200–205
Reel Level Proximity Switch Adjustment Lift Arm Angle
degrees 17 ± 1
Reel Level Proximity Switch to Lift Arm Air Gap
in. (mm) 0.118–0.196 (3–5)
Specification
Solenoid Nut Torque lb-ft (N·m) 10 (13.6)
Brake Solenoid Nut Torque
lb-in. (N·m) 33–53 (4–6)
4-4 4241262-Rev B
ELECTRICAL
4
Theory and Diagnostic
Information
Electrical Component Symbols
The following symbols are used in electrical schematics
to represent various electrical components.
Switches
1
1 The sample switch symbols shown are just a few of the many switch configurations. Switches are
designated by the number of “poles” (circuits controlled) and “throws” (actuator positions). Unless otherwise
specified, switches are shown in “Normally Open” (N.O.) position.
Single Pole, Single Throw
(SPST)
Double Pole, Single Throw
(DPST)
Single Pole, Double Throw
(SPDT)
Double Pole, Double Throw
(DPDT)
Proximity Switch
Switching Devices
Temperature Switch Pressure Switch
Relay
Circuit Protection Devices
Fuse Circuit Breaker
N.O.
Blk Wht
(+)
t˚
P
87 87A85
86 30
ELECTRICAL
4241262-Rev B 4-5
4
Motors and Generating Devices
Electric Motors (may also
include “AC” or “DC.”)
Stator
Alternator
Actuating Devices
Solenoid Valve PTO Clutch
Engine-Related Devices
Ignition Coil Spark Plug
Regulator Fuel Shutoff Solenoid
Lights
Single-Element Light Dual-Element Light
M
G
G
U
3
U
Pull-In Hold-In
4-6 4241262-Rev B
ELECTRICAL
4
Miscellaneous Symbols
Enclosure
(cabinet, housing, etc.)
Wires (crossing but not
connected)
Ground (to earth) Wiring Connections
Ground (to chassis) Coil
Direct Current (DC)
(as shown on an oscilloscope)
Battery
Alternating Current (AC)
(as shown on an oscilloscope)
Diode
Resistor Pin and Socket Connector
(+)
(-)
ELECTRICAL
4241262-Rev B 4-7
4
Electrical Schematic Component Identification
Electrical components shown in the main schematic are identified with an alphanumeric callout. All electrical
components shown in the electrical schematic are listed below.
• A1—Main Control Unit (See Figure 4-4.)
• A2—Liquid Crystal Display (LCD) (See Figure 4-1.)
• A3—Traction Pedal Position Sensor (See
Figure 4-5.)
• B1—Engine Oil Pressure Switch (See Figure 4-3.)
• B2—Hydraulic Oil Level Switch (See Figure 4-3.)
• B3—Hydraulic Filter Pressure Switch (See
Figure 4-4.)
• B4—Engine Temperature Sensor (See Figure 4-3.)
• CB1—50A Circuit Breaker (See Figure 4-3.)
• E1—Left Work Light (See Figure 4-5.)
• E2—Right Work Light (See Figure 4-5.)
• F1—20A Fuse (See Figure 4-4.)
• F2—20A Fuse (See Figure 4-4.)
• F3—10A Fuse (See Figure 4-1.)
• F4—10A Fuse (See Figure 4-3.)
• G1—12V Battery (See Figure 4-3.)
• G2—Alternator (See Figure 4-3.)
• H1—Horn (See Figure 4-1.
• J9—Diagnostic Connector (See Figure 4-2.)
• J10A—Seat Connector (See Figure 4-3.)
• J10B—Deluxe Seat Connector (See Figure 4-3.)
• J99—12V Accessory Socket (See Figure 4-1.)
• K1—Start Relay (See Figure 4-3.)
• K2—Glow Plug Relay (See Figure 4-3.)
• M1—Starter Motor (See Figure 4-3.)
• R1—Glow Plugs (See Figure 4-3.)
• S1—Key Switch (See Figure 4-1.)
• S2—Horn Switch (See Figure 4-2.)
• S3—Work Light Switch (See Figure 4-2.)
• S4—Park Brake Switch (See Figure 4-2.)
• S5—Mow Switch (See Figure 4-2.)
• S6—Cruise Control Switch (See Figure 4-2.)
• S7—Raise/Lower Switch (See Figure 4-2.)
• S8—Seat Switch (See Figure 4-3.)
• S10—Reel Level Proximity Switch (See Figure 4-5.)
• S11—Backlap Switch (See Figure 4-5.)
• Y1—Fuel Shutoff Solenoid (See Figure 4-3.)
• Y3—Front Mow Solenoid (See Figure 4-5.)
• Y4—Rear Mow Solenoid (See Figure 4-5.)
• Y5—Raise Solenoid (See Figure 4-5.)
• Y6—Lower Solenoid (See Figure 4-5.)
• Y7—Front Backlap Solenoid (See Figure 4-5.)
• Y8—Rear Backlap Solenoid (See Figure 4-5.)
• Y9—Traction Solenoid (See Figure 4-5.)
• Y10—Brake Solenoid (See Figure 4-5.)
4-8 4241262-Rev B
ELECTRICAL
4
Electrical Schematic
See Figures 4-1 through 4-5.
Figure 4-1
S1
Key
Switch
A2
Liquid
Crystal
Display
(LCD)
Off
Run
Start
A
B
C
D
J87-1 438 Wht
438 Wht
J87-2 440 Blk
50E
Red
80B
Red
433
Blk
429
Blk
447 Blk
Sp-600B
Sp-600A
434
Blk
20E
Blk
400B
Grn
410B
Yel
J8-5
J8-4 J8-3
J8-1
441
Grn
442
Yel
400B Grn
410B Yel
80B Red
431
Red
430 Red
J11-8
Ignition
J12-2
Start
J11-9 Horn Output (-)
Raise Input J12-7
Park Brake Switch J12-6
Mow Switch J12-5
+12V Power Supply J11-6
Light Switch J12-9
Cruise Switch J12-4
Horn Switch J12-10
Ground
J11-7
CAN
Shield
J11-1
CAN
Low
J11-11
CAN
High
J11-12
J10
435 Gry/Red
436
Gry/
Red
437
Gry/
Red
439
Gry/
Red
432 Red
432 Red
449 Red
452 Org
455 Wht/Grn
461 Lt Blu
446 Blk/Red 446 Blk/Red
461 Lt Blu
455 Wht/Grn
449 Red
444 Wht
452 Org
H1
Horn
J8-2
Sp-500A
Sp-500B
50E Red
463 Pur463 Pur
Lower Input J12-8
458 Brn458 Brn
J99
12V
Accessory
Socket
F3
10A
Fuse
465
Blk
464
Red
A
B
Unswitched Power Circuit
Switched Power Circuit
12V Power Supply
Ground Circuit
TN2847
ELECTRICAL
4241262-Rev B 4-9
4
Electrical Schematic
Continued
Figure 4-2
J9
Diagnostic
Connector
400B Grn
410B Yel
400A Grn
410A Yel
80B Red 80B Red
446 Blk/Red
Raise
Off
Lower
J19-1 454 Red
J19-6 457 Red
J19-2
J19-5
S7
Raise/Lower
Switch
50E Red50E Red
432 Red 432 Red
432
Red
450
Red
456
Red
453
Red
459
Red
462
Red
445
Red
Sp-400A
458 Brn
455 Wht/Grn
449 Red J13-3 J13-2 448 Red
400C Grn
410C Yel
400C Grn
410C Yel
400C Grn
410C Yel
S4
Park
Brake
Switch
452 Org J18-3 J18-2 451 Red
S5
Mow
Switch
100I Wht
On
Off
Sp-400B
Sp-400C
446 Blk/Red J17-3 J17-2 445 Red
S6
Cruise
Control
Switch
Sp-400D
Sp-400E
Unswitched Power Circuit
Switched Power Circuit
12V Power Supply
Ground Circuit
On
Off
Off
On
S3
Work
Light
Switch
461 Lt Blu J15-3 J15-2 460 Red
On
Off
463 Pur J14-3 J14-2 462 Red
S2
Horn
Switch
On
Off
445
Red
TN2848
4-10 4241262-Rev B
ELECTRICAL
4
Electrical Schematic
Continued
Figure 4-3
50E Red
400C Grn
410C Yel
400C Grn
410C Yel
400C Grn
410C Yel
400C Grn
410C Yel
Brn/YelBrn/Yel
80B Red80B Red80B Red
G
U
3
8787A 85
8630
20N
Blk
60B
Org/
Blu
230
Gry/
Red
240
Pur/
Wht
I
100B
Org/
Pnk
50F Red
50A Red
50B Red
50C Red
50D Red
50D Red
50C Red
50D Red
50C Red
50D Red
50C Red
50E Red
Blk
Red
Brn/Yel
60A Org/Blu 60A Org/Blu
60A
Org/
Blu
220
Blu/
Blk
210
Blu/
Wht
20M
Blk
50A Red B L
M1
Starter
Motor
K2
Glow
Plug
Relay
K1
Start
Relay
R1
Glow
Plugs
M
G1
Battery
G2
Alternator
Splice 100Splice 100Splice 100
100I Wht 100I Red
270 Red/Wht
Red
CB1
50A
Circuit
Breaker
F4
10A
Fuse
180 Grn/Yel
190 Wht
230 Gry/Red
230 Gry/Red
210 Blu/Wht
370 Gry/Wht
370 Gry/Wht
130 Grn
130 Grn
270 Red/Wht
B2
Hydraulic Oil
Level
Switch
8787A 85
8630
P
120 Blu
120
Blu
100E
Org/
Pnk
B1
Engine
Oil
Pressure
Switch
Y1
Fuel
Shutoff
Solenoid
Pull-In Hold-In
B4
Engine
Temperature
Sensor
100F Org/Pnk 200A Pur/Org 200B Pur/Org
J10A-1
J10A-2
S8
Seat
Switch
Deluxe
Seat
Connector
100H Org/Pnk J10B-1
On
Off
200C Pur/OrgJ10B-3
Red J10B-5
BlK J10B-4
Unswitched Power Circuit
Switched Power Circuit
Ground Circuit
(+)
(-)
TN2849
ELECTRICAL
4241262-Rev B 4-11
4
Electrical Schematic
Continued
Figure 4-4
400C Grn
410C Yel
170 Brn/Yel
80A Red
80B Red
80C Red
J2-8 Ignition Input
50D Red
50C Red
50C
Red
50D
Red
F1
20A
Fuse
F2
20A
Fuse
Splice 100
100A
Org/
Wht
Splice 100
Splice 100
20P
Blk
20V
Blk
25 PSI
Ground
J3-11
180 Grn/Yel
230 Gry/Red
210 Blu/Wht
190 Wht
J2-10 Fuel Hold Output (+)
J3-1 Fuel Pull-In Output (+)
Light Output (+) J3-5
Hydraulic Filter Pressure Switch Input J1-9
J2-5 Glow Plug Relay Output (+)
J2-6 Start Relay Output (+)
J3-6
12V
Input
J3-4
12V
Input
J3-3
12V
Output
170 Brn/Yel
420 Blu/Yel
420
Blu/
Ye l
J3-12 Fuel Pull-in Input
370 Gry/Wht
J1-4 Hydraulic Oil Level Input
130 Grn
J3-2 Engine Temperature Sensor Input
270 Red/Wht
J2-7 Alternator Input
J1-1 Seat Switch Input
J1-5 Select 1 Input
Raise Solenoid Output (+) J2-1
40 Blk 40 Blk
Signal Ground J3-8
330 Pur/Pnk 330 Pur/Pnk
Reel Level Switch Input J1-12
290A Gry/Blk 290A Gry/Blk
Backlap Switch Input J1-3
Brake Solenoid Output (+) J2-9
Traction Solenoid Forward Output J3-10
260 Gry/Blk 260 Gry/Blk
250A Gry/Org 250A Gry/Org
390A Blu/Tan390A Blu/Tan
Backlap Solenoid Output (+) J2-3
290B Gry/Blk 290B Gry/Blk
Traction Solenoid Reverse Output J3-9
250B Blk 250B Blk
B3
Hydraulic
Filter
Pressure
Switch
A1
Main
Control
Unit
(MCU)
30 Wht 30 Wht
Traction Pedal Sensor J3-7
P
340 Tan/Blu340 Tan/Blu
Lower Solenoid Output (+) J2-4
350 Tan/Grn350 Tan/Grn
Mow Solenoid Ountput (+) J2-2
300A Gry/Org 300A Gry/Org
120 Blu
J1-10 Engine Oil Pressure Switch Input
400C
Grn
410C
Yel
CAN
Low
J1-7
CAN
High
J1-8
200B Pur/Org
Unswitched Power Circuit
Switched Power Circuit
Ground Circuit
TN2850
4-12 4241262-Rev B
ELECTRICAL
4
Electrical Schematic
Continued
Figure 4-5
Splice 100
Splice 100 Splice 100
330 Pur/Pnk
290A Gry/Blk 290A Gry/Blk
260 Gry/Blk
250A Gry/Org
290B Gry/Blk 290B Gry/Blk
250B Blk
N.O.
160
Pur/
Org
100C
Org/
Pnk
40 Blk
30 Wht
390A Blu/Tan
S10
Reel
Level
Proximity
Switch
340 Tan/Blu 340 Tan/Blu
350 Tan/Grn 350 Tan/Grn
300A Gry/Org
Blk2 Wht
1
20U
Blk
20R
Blk
20S
Blk
300C
Gry/
Org
350
Tan/
Grn
340
Tan/
Blu
Y3
Front
Mow
Solenoid
20J
Blk
300B
Gry/
Org
Y4
Rear
Mow
Solenoid
Y8
Rear
Backlap
Solenoid
Y5
Raise
Solenoid
Y6
Lower
Solenoid
20F
Blk
260
Gry/
Blk
Y10
Brake
Solenoid
250B
Blk
250A
Gry/
Org
Y9
Traction
Solenoid
20B
Blk
390B
Blu/
Tan
E1
Left
Work
Light
20C
Blk
390C
Blu/
Tan
E2
Right
Work
Light
20T
Blk
290C
Gry/
Blk
Y7
Front
Backlap
Solenoid
20H
Blk
290D
Gry/
Blk
S11
Backlap
Switch
On
Off
A3
Traction
Pedal
Position
Sensor
J7-3 Signal
J7-2 Ground
30 Wht
40 Blk
J7-1
12V
100G
Org/
Wht
Switched Power Circuit
Ground Circuit
TN2851
ELECTRICAL
4241262-Rev B 4-13
4
Theory of Operation and
Sub-Circuit Schematics
Power Circuit—Theory of Operation
See Figures 4-1 through 4-5.
Unswitched Power Circuit
Unswitched power is available from the battery positive
terminal to the starter motor battery terminal, and then
from the starter motor battery terminal to the alternator
battery terminal. Unswitched power is also available from
the starter motor battery terminal to 50A circuit breaker
battery terminal.
50A circuit breaker battery terminal provides unswitched
power to the following:
• Main control unit connector J3-4
• Main control unit connector J3-6
• 10A fuse F4
50A circuit breaker output terminal provides unswitched
power to the following:
• Start relay terminal 30
• Glow plug relay terminal 30
• 10A fuse F3 input terminal
Fuse F3 input terminal provides unswitched power to key
switch terminal A. The 10A fuse F3 output terminal
provides unswitched power to the12V accessory socket.
Switched Power Circuit
When the key switch is turned to the run position, voltage
is provided from key switch terminal B to liquid crystal
display (LCD) ignition terminal J11-8, and to main control
unit (MCU) ignition terminal J2-8, powering up the LCD
and MCU.
Voltage is also provided from key switch terminal B to
MCU select 1 input terminal J1-5, activating the input.
With the select 1 input activated, the MCU selects the
software program for this model machine. This allows the
MCU to be used in more than one model machine.
With the LCD powered up, voltage is provided from the
LCD 12 volt power supply terminal J11-6 to the following:
• Horn switch
• Work light switch
• Park brake switch
• Mow switch
• Raise/lower switch
With the MCU powered up, voltage is provided from the
MCU 12V output terminal J3-3 to the following:
• Hydraulic oil level switch
• Seat switch
• Alternator terminal
• Reel level proximity switch
• Backlap switch
• Traction pedal position sensor
The MCU provides internal protection for the 12V output
circuit and to the input and output terminals.
4-14 4241262-Rev B
ELECTRICAL
4
Diesel Engine Circuit—Theory of
Operation
Power Circuit
When the key switch is turned to the run position, voltage
is provided from key switch terminal B to liquid crystal
display (LCD) ignition terminal J11-8, and to main control
unit (MCU) ignition terminal J2-8, powering up the LCD
and MCU. (See “Power Circuit—Theory of Operation” on
page 4-13.)
Glow Plug Circuit
With the MCU powered up, 12 volts is provided from the
MCU glow plug relay output terminal J2-5 to glow plug
relay terminal 86, energizing the relay. With the relay
energized, voltage is switched between relay terminals
30 and 87 and is provided to the glow plugs, heating the
glow plugs. At the same time the MCU instructs the LCD
to turn on the glow plug light through the controller area
network (CAN).
Glow plug timing is determined by the engine
temperature sensor input. If the temperature is greater
than 50° F (10° C), glow plug activation is not required.
Interlock Circuit
To start and operate the engine with the operator off or
on the seat, the following must occur:
• Mow switch in the off position
• Park brake switch in the on position
• Traction pedal in the neutral position
When the mow switch is placed in the off position,
voltage is not provided from the switch to the LCD mow
switch input terminal J12-5, indicating the switch is in the
off position.
When the park brake switch is in the on position, voltage
is provided to the LCD park brake switch input terminal
J12-6, indicating the switch is in the on position.
LCD communicates the status of the mow and park brake
switch to the MCU.
The MCU uses the traction pedal position sensor voltage
level to determine when the traction pedal is in the
neutral position. When the traction pedal is in the neutral
position, the sensor output voltage level is approximately
2.5 volts. Traction pedal position sensor signal terminal
J7-3 connects to MCU traction pedal sensor input
terminal J3-7.
Start Circuit
When the key switch is turned to the start position,
voltage is provided from key switch terminal C to the LCD
start input terminal J12-2, activating the input. The status
of the key switch is communicated between LCD and the
main control unit (MCU) through the controller area
network (CAN).
With the key switch (status) in the start position, voltage
is provided from the MCU fuel hold output terminal J2-10
to the fuel shutoff solenoid's hold-in coil.
The MCU start output terminal J2-6 provides voltage to
start relay terminal 86, energizing the relay. With the start
relay energized, voltage is switched between relay
terminals 30 and 87 and provided to the starter motor
solenoid, energizing the solenoid. With the starter
solenoid energized, voltage is switched between the
starter solenoid contacts to the starter motor, engaging
the motor.
The MCU will engage the starter for only 10 seconds. If
the engine fails to start, the key switch must be turned to
the off position before attempting to start again.
With the starter solenoid energized, voltage is also
provided from the starter solenoid contacts to MCU fuel
pull-in input terminal J3-12, activating the input. With the
fuel pull-in input activated, MCU fuel pull-in output
terminal J3-1 provides voltage to the fuel shutoff solenoid
pull-in coil, energizing the coil. With the pull-in coil
energized, the solenoid plunger retracts.
When the solenoid plunger is fully retracted, an internal
switch opens the pull-in coil circuit. This prevents
extended activation of the high current pull-in coil. The
hold-in coil keeps the solenoid plunger in the retracted
position until it is de-energized.
With the solenoid plunger retracted, fuel is allowed to
flow, and as the starter motor cranks the engine, the
engine starts operating.
Run Circuit
When the operator is on the seat, the seat switch
contacts close. With the seat switch contacts closed,
voltage is provided to MCU seat switch input terminal
J1-1, activating the input. With the input activated, the
MCU allows the engine to continue to operate when the
park brake switch is in the off position. With the seat
switch input activated, MCU fuel hold-in output terminal
J2-10 continues to provide voltage to the fuel shutoff
solenoid hold-in coil, keeping the fuel shutoff solenoid
plunger retracted. With the solenoid plunger retracted,
fuel continues to flow to the engine.
The MCU will de-energize the fuel shutoff solenoid if the
operator leaves the seat with the mow switch in the on
position or with the park brake switch in the off position.
ELECTRICAL
4241262-Rev B 4-15
4
Charging Circuit
With the engine running, switched power is provided to
the alternator field terminal, exciting the alternator. With
the alternator field terminal excited, the alternator
produces three-phase alternating current (AC). The AC
voltage is provided to the alternator's internal voltage
regulator.
When the battery voltage is low, the voltage regulator
provides regulated voltage to charge the battery.
When the battery is fully charged, the regulator stops
providing regulated voltage to the battery.
When the 12V battery drops to a specific voltage, the
alternator L terminal provides a ground to the MCU
alternator input terminal J2-7, activating the input. With
the alternator input activated, the MCU instructs the LCD
to turn on the 12V battery light through the controller area
network (CAN).
4-16 4241262-Rev B
ELECTRICAL
4
Diesel Engine Circuit Schematic
See Figures 4-6 through 4-8.
Figure 4-6
Unswitched Power Circuit
Interlock Circuit
Switched Power Circuit
12V Power Supply
Start Circuit
Ground Circuit
400C Grn
410C Yel
S1
Key
Switch
A2
Liquid
Crystal
Display
(LCD)
Off
Run
Start
A
B
C
D
50E
Red
80B
Red
433
Blk
429
Blk
447 Blk
Sp-600B
Sp-600A
434
Blk
20E
Blk
400B
Grn
410B
Yel
J8-5
J8-4 J8-3
J8-1
441
Grn
442
Yel
80B Red
431
Red
430 Red
J11-8
Ignition
J12-2
Start
Park Brake Switch J12-6
Mow Switch J12-5
+12V Power Supply J11-6
Ground
J11-7
CAN
Shield
J11-1
CAN
Low
J11-11
CAN
High
J11-12
J10
435 Gry/Red
436
Gry/
Red
437
Gry/
Red
439
Gry/
Red
432 Red
449 Red
452 Org
444 Wht
J8-2
Sp-500A
50E Red
432 Red 432 Red
432
Red
450
Red
Sp-400A
J13-3 J13-2 448 Red
S4
Park
Brake
Switch
J18-3 J18-2 451 Red
S5
Mow
Switch
F3
10A
Fuse
On
Off
Sp-400B
J9
Diagnostic
Connector
400A Grn
410A Yel
J99
12V
Accessory
Socket
465
Blk
464
Red
A
B
On
Off
TN2855
ELECTRICAL
4241262-Rev B 4-17
4
Diesel Engine Circuit Schematic
Continued
Figure 4-7
50E Red
400C Grn
410C Yel
400C Grn
410C Yel
400C Grn
410C Yel
400C Grn
410C Yel
Brn/YelBrn/Yel
80B Red80B Red80B Red
G
U
3
8787A 85
8630
20N
Blk
60B
Org/
Blu
230
Gry/
Red
240
Pur/
Wht
I
100B
Org/
Pnk
50F Red
50A Red
50B Red
50C Red
50D Red
50D Red
50C Red
50D Red
50C Red
50D Red
50C Red
50E Red
Blk
Red
Brn/Yel
60A Org/Blu 60A Org/Blu
60A
Org/
Blu
220
Blu/
Blk
210
Blu/
Wht
20M
Blk
50A Red B L
M1
Starter
Motor
K2
Glow
Plug
Relay
K1
Start
Relay
R1
Glow
Plugs
M
G1
Battery
G2
Alternator
Splice 100Splice 100100B Org/Pnk
270 Red/Wht
Red
CB1
50A
Circuit
Breaker
180 Grn/Yel
190 Wht
230 Gry/Red
230 Gry/Red
210 Blu/Wht
130 Grn
130 Grn
270 Red/Wht
8787A 85
8630
Y1
Fuel
Shutoff
Solenoid
Pull-In Hold-In
B4
Engine
Temperature
Sensor
100F Org/Pnk 200A Pur/Org 200B Pur/Org
J10A-1
J10A-2
S8
Seat
Switch
On
Off
Unswitched Power Circuit
Switched Power Circuit
Glow Plug Circuit
Start Circuit
Charging Circuit
Fuel Pull-in Circuit
Fuel Hold Circuit
Interlock Circuit
Ground Circuit
(+)
(-)
TN2856
4-18 4241262-Rev B
ELECTRICAL
4
Diesel Engine Circuit Schematic
Continued
Figure 4-8
400C Grn
410C Yel
170 Brn/Yel
80A Red
80B Red
80C Red
J2-8 Ignition Input
50D Red
50C Red
50C
Red
50D
Red
Splice 100
100A
Org/
Wht
Splice 100
20P
Blk
Ground
J3-11
180 Grn/Yel
230 Gry/Red
210 Blu/Wht
190 Wht
J2-10 Fuel Hold Output (+)
J3-1 Fuel Pull-In Output (+)
J2-5 Glow Plug Relay Output (+)
J2-6 Start Relay Output (+)
J3-6
12V
Input
J3-4
12V
Input
J3-3
12V
Output
170 Brn/Yel
J3-12 Fuel Pull-in Input
130 Grn
J3-2 Engine Temperature Sensor Input
270 Red/Wht
J2-7 Alternator Input
J1-1 Seat Switch Input
J1-5 Select 1 Input
40 Blk
Signal Ground J3-8
A1
Main
Control
Unit
(MCU)
30 Wht
Traction Pedal Sensor J3-7
400C
Grn
410C
Yel
CAN
Low
J1-7
CAN
High
J1-8
A3
Traction
Pedal
Position
Sensor
J7-3 Signal
J7-2 Ground
30 Wht
40 Blk
J7-1
12V
100G
Org/
Wht
200B Pur/Org
Unswitched Power Circuit
Switched Power Circuit
Glow Plug Circuit
Start Circuit
Charging Circuit
Fuel Pull-in Circuit
Fuel Hold Circuit
Interlock Circuit
Ground Circuit
F1
20A
Fuse
F2
20A
Fuse
TN2857
ELECTRICAL
4241262-Rev B 4-19
4
Raise/Lower Circuit—Theory of
Operation
Power Circuit
When the key switch is turned to the run position, voltage
is provided from key switch terminal B to liquid crystal
display (LCD) ignition terminal J11-8, and to main control
unit (MCU) ignition terminal J2-8, powering up the LCD
and MCU. (See “Power Circuit—Theory of Operation” on
page 4-13.)
Raise Circuit
When the raise/lower switch is placed in the raise
position, voltage is provided to the LCD raise input
terminal J12-7, activating the input. With the input
activated, the LCD communicates the status of the raise
switch to MCU through the controller area network
(CAN).
After receiving the raise switch status from the LCD, the
MCU raise solenoid output terminal J2-1 provides voltage
to the raise solenoid, energizing the solenoid. With the
solenoid energized, the cutting units will rise until the
raise/lower switch is released, or until the cutting units
reach their end of travel.
Lower Circuit
When the raise/lower switch is placed in the lower
position, voltage is provided to the LCD lower input
terminal J12-8, activating the input. With the input
activated, the LCD communicates the status of the lower
switch to MCU through the controller area network
(CAN).
After receiving the lower switch status from the LCD, the
MCU lower solenoid output terminal J2-4 provides
voltage to the lower solenoid, energizing the solenoid.
With the solenoid energized, the cutting units will lower
until the raise/lower switch is released, or until the cutting
units are fully lowered.
Note: While mowing, the raise/lower function will be in
“one touch crosscut” mode, meaning the raise/lower
lever only needs to be tapped to move the cutting units to
a pre-determined position. When not mowing, the
raise/lower lever must be held until the cutting units reach
the desired position.
4-20 4241262-Rev B
ELECTRICAL
4
Raise Circuit Schematic
See Figures 4-9 and 4-10.
Figure 4-9
Unswitched Power Circuit
Switched Power Circuit
12V Power Supply
Raise Circuit
Ground Circuit
S1
Key
Switch
A2
Liquid
Crystal
Display
(LCD)
Off
Run
Start
A
B
C
D
J87-1 438 Wht
438 Wht
J87-2 440 Blk
50E
Red
80B
Red
433
Blk
429
Blk
447 Blk
Sp-600B
Sp-600A
434
Blk
20E
Blk
400B
Grn
410B
Yel
J8-5
J8-4 J8-3
J8-1
441
Grn
442
Yel
400C Grn
410C Yel
80B Red
431
Red
430 Red
J11-8
Ignition
J12-2
Start
J11-9 Horn Output (-)
Raise Input J12-7
+12V Power Supply J11-6
Ground
J11-7
CAN
Shield
J11-1
CAN
Low
J11-11
CAN
High
J11-12
J10
435 Gry/Red
436
Gry/
Red
437
Gry/
Red
439
Gry/
Red
432 Red
444 Wht
H1
Horn
J8-2
Sp-500A
Sp-500B
J19-1 454 Red
J19-6 457 Red
J19-2
J19-5
S7
Raise/Lower
Switch
50E Red
432
Red
456
Red
453
Red
Lower Input J12-8
458 Brn
455 Wht/Grn
J9
Diagnostic
Connector
400A Grn
410A Yel
J99
12V
Accessory
Socket
F3
10A
Fuse
465
Blk
464
Red
A
B
Sp-400C
Sp-400D
Raise
Off
Lower
TN2858
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