Diode Circuit Boards - Toro 04384 Service Manual

Diode Circuit Boards

The Greensmaster 3250--D electrical system uses two
(2) diode circuit boards that are inserted into wire har-
ness connectors. Each of these circuit boards contain
four (4) diodes. The diodes are used for circuit protec-
tion from inductive voltage spikes and for safety circuit
logic.
Apply dielectric grease (Toro part number 107--0342) to
circuit board contacts whenever the circuit board is
installed into the wire harness.
NOTE: The Greensmaster 3250--D does not use
diodes D1--B or D2--B.
Diode D1- -A allows current flow to solenoid S2 when the
lower relay is energized. It also prevents current flow to
solenoid S4 when the raise relay is energized.
Diode D1- -C prevents a negative spike from damaging
the mow sensor and backlap switch by allowing a
ground path for the mow relay when it de--energizes.
Diode D1- -D allows current flow to solenoid S2 when the
raise relay is energized. It also prevents current flow to
solenoid S4 when the lower relay is energized.
Diode D2- -A 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 D2- -C maintains current flow to the joystick relay
after the momentary lower switch of the joystick opens.
Diode D2- -D allows the engine to start only with the
functional control lever in NEUTRAL (neutral sensor
closed). Also, it allows the engine to continue to run with
either the functional control lever in NEUTRAL (neutral
sensor closed) or the operator sitting in the seat (seat
switch closed) with the parking brake released (parking
brake sensor closed).
Testing
The circuit board diodes can be individually tested using
a digital multimeter (ohms setting) and the table to the
right. If any of the diodes on the circuit board are dam-
aged, the diode circuit board must be replaced.
Electrical System
Red Lead (+)
on Terminal
H
A
G
B
F
C
E
D
Page 5 - - 16
D
A
DIODE
C
CIRCUIT
BOARD
B
Figure 15
A
B
C
D
DIODE
DIAGRAM
Figure 16
Black Lead (- -)
on Terminal Continuity
A
H
B
G
C
F
D
E
Greensmaster 3250--D
YES
NO
YES
NO
YES
NO
YES
NO