Diodes - Toro Greensmaster 3150 Service Manual

Diodes

The main wiring harness contains six (6) diodes. Diodes
D2 and D3 are connected to the harness at separate
locations. Diodes D1--A, D1--B, D1--C and D1--D are
connected to the main harness by a four (4) position cir-
cuit 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.
Apply dielectric grease (Toro part number 107--0342) to
circuit board contacts whenever the circuit board is
installed into the wire harness.
Diode D1- -A
Allows the engine to start only with the functional control
lever in NEUTRAL (neutral switch closed). Also, it allows
the engine to continue to run with either the functional
control lever in NEUTRAL (neutral switch closed) or the
operator sitting in the seat (seat switch closed).
Diode D1- -B
Prevents a negative spike from damaging the neutral
switch 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 (K3) after the
momentary 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 (K4) 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
(K6).
Diode D3
This diode prevents current flow to solenoid S3 when so-
lenoids S2 and S4 are energized through lower relay
(K5).
Testing
The diodes can be individually tested using a digital
multimeter (ohms setting) and the table to the right.
Electrical System
DIODE
CIRCUIT
D1--D
BOARD
D1--C
DIODE CIRCUIT BOARD
Type Red (+)
Circuit
Board
Plug-In
DIODE
CIRCUIT BOARD
Page 5 - - 22
1/A
D1--A
D1--B
Figure 25
D1--A
D1--B
D1--C
D1--D
Figure 26
Black (- -)
H A
A H
G B
B G
F C
C F
E D
D E
1/A 2/B
2/B 1/A
Figure 27
Greensmaster 3150
PLUG-IN
DIODE
2/B
Continuity
YES
NO
YES
NO
YES
NO
YES
NO
YES
NO