Rmc Module; Key Switch - Craftsman 28906 Professional Shop Manual

ELECTRICAL
SYSTEM
ELECTRICAL SYSTEM
COMPONENTS
RMC Module
The RMC module contains electronic logic circuits.
When diagnosing anything that is connected to the
RMC module, a high impedance test light or a high
impedance digital multi-meter (DMM) must be used.
The amperage draw of a standard incandescent test
light may over-burden some internal electronic circuits,
burning-out the module.
Key switch
The Key Switch is similar to those used in a variety of
MTD applications since 1999. The difference in this
case is that it is incorporated in the same housing as
the RMC module; the two items are not available sepa-
rately. See Figure 7.1.
RMC Module
It is typical when industries shift from electro-
mechanical to electronic controls that diagnosis
shifts from tracing through a number of indepen-
dent circuits to checking the in-puts to and out-
puts from a central processor. This is similar to,
but much less complex than the transition that
the auto industry made with the conversion to
fuel injection in the 1980s.
NOTE: The starter safety circuit has no connec-
tion to the RMC module.
The only one switch in the safety circuit that is
capable of turning-off the engine works through
the RMC module.
It is still important to be familiar with the workings
of the individual components of the electrical
system, but some of them can now be checked
from a central point on the tractor. This makes
life easier on the technician, frequently making it
unnecessary to connect to difficult to reach
switches in the preliminary stages of trouble-
shooting.
The function of individual safety switches can be
seen as providing information "inputs" to the
RMC module.
The next part of this section gives a detailed
description of the electrical components on this
tractor, their function in the system, and their
physical location on the tractor. Armed with this
information and the proper tools, a technician
should be able to efficiently diagnose most elec-
trical problems.
,
Key Switch
Figure 7.1
In the OFF position, continuity can be found
between the M, G, and A1 terminals.
See Figure 7.2.
Off
Key Switch Schematic
A2
Start
S B
1
2
Run w/RMC
S
L
M
A2
Run
Figure 7.2
3