MTD 700 Series Professional Shop Manual page 102

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Series 700 Lawn Tractor
1. Disconnect the molded 8-pin plug from the OCR
module.
NOTE: The 7-pin module had a jumper harness that
is between the module and the main har-
ness. When performing the pin test, use the
jumper connector that connects to the mod-
ule (unless otherwise noted).
See Figure 7.7.
NOTE: The jumper harness changes the pin loca-
tions of the yellow wires.
2. Looking at the plug head-on, it will be configured as
shown in the diagram: There will be 8 female pin
terminals. When probed, they should yield the
results described in the following sections.
See Figure 7.8.
3. Check the PTO and seat safety circuits with the 8-
pin pigtail connector unplugged, then reconnect it
and continue with the OCR plug test.
Yellow wire with black trace
• Behavior: When the female pin terminal lead-
ing into the main harness is probed (yellow wire
with black trace), it should show continuity to
ground with the seat empty and the PTO OFF.
• With the seat occupied, the key switch OFF and
the PTO ON, it should show continuity to
ground.
• Circuitry: The yellow wire with a black trace
tees into the wire that provides a ground path
from the seat switch to the PTO switch when
the seat is vacant.
• If there is not continuity to ground when the
seat is empty, and the PTO OFF, the seat
switch is not working properly or it has lost its
ground.
• If there is not continuity to ground when the
seat is occupied, and the PTO ON, either the
PTO switch is not working properly or it has lost
its connection to the magneto circuit.
NOTE: The PTO switch should the a ground signal
from the M terminal of the key switch when it
is in the OFF position.
• Interpretation: If behavior is correct, the seat
switch and PTO switch are functioning properly.
NOTE: On tractors equipped with the 7-pin module,
the seat switch and the PTO switch can be tested separately by unplugging the jumper harness and
testing at the main harness. The yellow wire with a white stripe is the seat switch and yellow wire with a
black stripe is the PTO switch.
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Jumper harness
Test here
Figure 7.7
7-pin jumper connector
8-pin connector
Figure 7.8