Table of Contents
Advertisement
Electrical Troubleshooting Using The
Tractor Control Module (TCM)
The TCM monitors the electronic circuits necessary for
the engine, starter, and PTO to function. These "input"
circuits include the PTO Switch, Neutral Switch, Parking
Brake Switch, Key Switch, Seat Switch, and Generator
Presence. The TCM is programmed to allow the engine,
starter, or PTO to operate only when specifi c input crite-
ria are satisfi ed. The engine, start, and PTO circuits are
controlled by "outputs" from the TCM.
For troubleshooting purposes, the TCM includes red
LED lights for each circuit. The LED lights will acti-
vate when the input or output circuit is activated. The
TCM is divided into two sections: the left (input) side
displays the 8 inputs with red LED lights; the right
(output) side displays the 5 outputs also with red LED
lights. The TCM has two power supplies. The fi rst
supplies powers to the computer independent of the
key switch so that the TCM does not turn on and off
with each key switch on & off cycle. (Note: When the
battery disconnect switch is turned to Off, the TCM is
also turned off). The second supply energizes the rest
of the computer when the key switch is turned on.
A
A
B
B
C
C
D
D
E
E
F
F
G
G
H
H
Input Circuits
Brake Switch (A)
The light indicates the circuit is closed and the park-
ing brake is engaged. In order for this light to oper-
ate, the key switch must be in the On position.
Neutral Switch (B)
The light indicates the circuit is closed and the
power unit's forward/reverse control is in neutral. In
order for this light to operate, the key switch must be
TROUBLESHOOTING
PTO Switch (C)
Seat Switch (D)
Engine Starter (E)
Key Switch On (F)
Generator Present (G)
K
K
L
L
Generator Switch (H)
M
M
N
N
O
O
Power (J)
J
J
Output Circuits
Specifi c input conditions must be satisfi ed before
each output circuit can function.
Starter (K)
Troubleshooting - 66
in the On position and the forward/reverse control
(SDLA) must be in the neutral position.
The light indicates the PTO switch is in the On posi-
tion. In order for this light to operate, the key switch
must be in the On position and the PTO switch must
be in the On (engaged) position.
The light indicates that an operator is present in the
seat. In order for this light to operate, the key switch
must be in the On position and the operator must be
present in the seat.
The light indicates that the key switch is turned to
the Start position.
The light indicates that the key switch is turned to
the On position. The key switch must be in the On
position for the TCM to activate.
The light indicates that the generator is connected to
the power unit, which activates a specifi c set of crite-
ria and allows the PTO to operate without an operator
present on the seat. In order for this light to operate,
the key switch must be in the On position and a gen-
erator must be connected to the power unit.
The light indicates that the switch on the genera-
tor is set to the On (engaged) position. In order for
this light to operate, the key switch must be in the
On position, a generator must be connected to the
power unit, and the switch on the generator must be
pulled up to the On (engaged) position.
This light is located at the bottom right corner of the
TCM. This light indicates that there is full time power
to the TCM and is only shut off by the battery discon-
nect switch. It keeps the TCM computer energized to
eliminate the delay that would otherwise be present
when the key switch is fi rst turned to the On position.
The light indicates that power is being sent to the
starter solenoid. For the starter output to function,
the parking brake must be set and the power unit's
forward/reverse control must be in neutral.
Advertisement
Table of Contents
Troubleshooting
