Diode Circuit Boards - Toro Greensmaster 3250-D 04383 Service Manual

Diode Circuit Boards

Each circuit board contains four diodes. The diodes are
used for circuit protection from inductive voltage spikes
and for safety circuit logic. Diode D8 is not used.
Diode D1
This diode prevents current flow to solenoid S3 when so-
lenoids S2 and S4 are energized through lower relay R6.
Diode D2
This diode prevents current flow to solenoid S4 when so-
lenoids S2 and S3 are energized through Raise relay
R5.
Diode D3
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 D4
This component is not used.
Diode D5
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 D6
Prevents a negative spike from damaging the Neutral
Sensor and Seat switch by allowing a ground path for
the Run relay when it de−energizes.
Diode D7
Maintains current flow to the Joystick relay after the mo-
mentary Lower switch of the Joystick opens.
Diode D8
This component is not used.
Testing
The diodes can be individually tested using a digital
multimeter (ohms setting) and the table to the right.
Electrical System (Rev. C)
Red Lead (+)
on Terminal
H
A
G
B
F
C
E
D
DIODE CIRCUIT BOARD
Page 5 − 20
D2
D6
D4
D8
D3
D7
D1
D5
DIODE
DIAGRAM
Figure 25
DIODE
CIRCUIT BOARDS
Figure 26
Black Lead (−)
on Terminal Continuity
A YES
H
B YES
G
C YES
F
D YES
E
Figure 27
Greensmaster 3250−D
NO
NO
NO
NO