Electrical Troubleshooting Using The Tractor Control Module (Tcm) - Ventrac 4500Y Operator's Manual

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, Park-
ing Brake Switch, Key Switch, Seat Switch, and Gen-
erator Presence. The TCM is programmed to allow the
engine, starter, or PTO to operate only when specific
input criteria are satisfied. 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
activate 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 first supplies powers to the computer indepen-
dent 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 sup-
ply energizes the rest of the computer when the key
switch is turned on.
When the battery disconnect switch is turned on, the
Power LED light (J) will illuminate. If the system volt-
age drops below a preset value when the key switch
is off, or if the power unit sits unused for more than
15 days, the TCM will automatically go to 'Sleep'
mode and enter a reduced power state. To 'Wake'
the TCM, turn the battery disconnect switch off for
10 seconds and then back on.
A
B
C
D
E
F
G
H
TROUBLESHOOTING
Input Circuits
Brake Switch (A)
Neutral Switch (B)
PTO Switch (C)
Seat Switch (D)
Engine Starter (E)
Key Switch On (F)
Generator Present (G)
Generator Switch (H)
K
Power (J)
L
M
N
O
J
Troubleshooting - 72
The light indicates the circuit is closed and the
parking brake is engaged. In order for this light to
operate, the key switch must be in the On position.
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 in the On position and the forward/reverse con-
trol (SDLA) must be in the neutral position.
The light indicates the PTO switch is in the On
position. 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.
Not applicable.
Not applicable.
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 or if the TCM enters the 'Sleep' mode. It
keeps the TCM computer energized to eliminate the
delay that would otherwise be present when the key
switch is first turned to the On position.