Standard Control Module (Scm) - Toro 03170 Operator's Manual

Figure 42
1. Bypass valve
2. Before starting the engine, close the bypass valve by
rotating it 90° (1/4 turn). Do not start the engine
while the valve is open.
Standard Control Module
(SCM)
The Standard Control Module is a potted electronic
device produced in a one-size-fits-all configuration. The
module uses solid state and mechanical components
to monitor and control standard electrical features
required for safe product operation.
The module monitors inputs including neutral, parking
brake, PTO, start, backlap, and high temperature. The
module energizes outputs including PTO, Starter, and
ETR (energize to run) solenoid.
The module is divided into inputs and outputs. Inputs
and outputs are identified by green LED indicators
mounted on the printed circuit board.
The start circuit input is energized by 12 VDC. All
other inputs are energized when the circuit is closed to
ground. Each input has a LED that is illuminated when
the specific circuit is energized. Use the input LEDs for
switch and input circuit troubleshooting.
Output circuits are energized by an appropriate set of
input conditions. The three outputs include PTO, ETR,
and START. Output LEDs monitor relay condition
indicating the presence of voltage at one of three
specific output terminals.
Output circuits do not determine output device
integrity, so electrical troubleshooting includes output
LED inspection and conventional device and wire
harness integrity testing. Measure the disconnected
component impedance, the impedance through wire
harness (disconnect at SCM), or by temporarily "test
energizing" the specific component.
The SCM does not connect to an external computer or
hand held device, can not be re-programmed, and does
not record intermittent fault troubleshooting data.
The decal on the SCM only includes symbols. Three
LED output symbols are shown in the output box. All
other LEDs are inputs. The chart below identifies the
symbols.
Here are the logical troubleshooting steps for the SCM
device.
1. Determine the output fault you are trying to resolve
(PTO, START, or ETR).
2. Move the key switch to the On position and ensure
that the red power LED is illuminated.
3. Move all the input switches to ensure that all LEDs
change state.
4. Position the input devices at the appropriate
position to achieve the appropriate output. Use the
following logic chart to determine the appropriate
input condition.
5. If the specific output LED is illuminated without
the appropriate output function, check the output
harness, connections, and component. Repair as
needed.
6. If the specific output LED is not illuminated, check
both fuses.
7. If the specific output LED is not illuminated and
the inputs are in the appropriate condition, install a
new SCM and determine if the fault disappears.
Each row (across) in the logic chart below identifies
input and output requirements for each specific product
function. The product functions are listed in the left
column. The symbols identify the specific circuit
condition including: energized to voltage, closed to
ground, and open to ground.
32
Figure 43