Diodes - Toro Greensmaster 3150 Service Manual

Diodes

The main wiring harness contains six diodes. Diodes D2
and D3 are connected to the harness at separate loca-
tions. Diodes D1–A, D1–B, D1–C, and D1–D are con-
nected to the main harness by a small four position
circuit board located near the front of the left side control
panel. The diodes are used for circuit protection from in-
ductive voltage spikes and for safety circuit logic.
Diode D1–A
Allows the engine to start only with the Functional Con-
trol Lever in NEUTRAL (neutral sensor closed). Also, it
allows the engine to continue to run with either the Func-
tional Control Lever in NEUTRAL (Neutral Sensor
closed) or the operator sitting in the seat (Seat switch
closed).
Diode D1–B
Prevents a negative spike from damaging the Neutral
Sensor and Seat switch by allowing a ground path for
the Start Safety relay (K2) when it de–energizes.
Diode D1–C
Maintains current flow to the Joystick relay after the mo-
mentary Lower switch of the Joystick opens.
Diode D1–D
Prevents a negative spike from damaging the Mow and
Backlap switches by allowing a ground path for the mow
relay when it de–energizes.
Diode D2
This diode prevents current flow to solenoid S4 when so-
lenoids S2 and S3 are energized through Raise relay
R5.
Diode D3
This diode prevents current flow to solenoid S3 when so-
lenoids S2 and S4 are energized through lower relay R6.
Testing
The diodes can be individually tested using a digital
multimeter (ohms setting) and the table to the right.
Greensmaster 3150
DIODE
CIRCUIT
D1–D
BOARD
D1–C
DIODE CIRCUIT BOARD
Type Red (+)
Circuit Circuit
Board
1/A
Plug-In Plug-In
2/B
DIODE
CIRCUIT BOARD
Page 5 – 17
PLUG-IN
DIODE
1/A
D1–A
D1–B
Figure 22
D1–A
D1–B
D1–C
D1–D
Figure 23
Black (–) Continuity
H A
A H
G B
B G
F C
C F
E D
D E
2/B
1/A
Figure 24
Electrical System
2/B
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO