Cub Cadet ISeries - Manual (Page 131)

ELECTRICAL SYSTEM
125
Increased resistance
Increased resistance is, as the name implies, an
increase in resistance.
This can be caused by loose or corroded connec-
tions, or connections that are insulated by grease,
paint, or coatings. Fasteners finished in oil/phosphate
or black oxide are bad conductors. Use bright fasten-
ers (zinc coated).
Resistance can be problem on the ground side as
well as the hot side of a system: remember that elec-
tricity must complete a loop (circuit) back to the battery
post. Any resistance in that loop will interfere with the
flow.
Arguably the most common electrical failure, and
the hardest to find, increased resistance can have
more subtle symptoms than outright open circuits.
Many times effected circuits will still partially function.
It is not an open because there is some current that
can get through, but the increase in resistance is
enough to affect the circuit.
The Tools
Equipment needed to diagnose an electrical system:
• DMMDMM (Digital Volt-Ohm Meter)
• Wiring schematic or diagram
Equipment that may be useful:
• Fused jumper wires.
• Test light
• Self-powered continuity light
• Ammeter
• Battery charger
• Battery tester
• Battery jumper cables
• Hand tools to gain access to components.
• Flash light.
Digital Multi-meter
A DMM is the most useful tool to trouble-shoot any
electrical system. There is an amazing variety of DMMs
on the market. Some are very basic, others are tailored
to specific industries, and some high-end graphing
meters function like oscilloscopes. Even the most basic
ones are quite versatile. See Figure 7.21.
Uses
Voltage
Set meter to read “Volts DC ( _ _ _ )” if using an
auto-ranging meter or to an appropriate scale (typically
20 Volts DC) if using a more basic model.
• Connect the meter in parallel to the circuit
being measured, between the test point and a
known-good ground. turn on the circuit to be
tested, and read the meter. For most tests the
engine need not be running, but the key will be
turned on.
• If the meter is connected with the polarity
reversed, a “-” will appear in front of the voltage
reading. It has no ill effects on the meter nor on
accuracy.
• If the meter is set to Volts AC (~) it may not reg-
ister any DC voltage, but no physical harm will
be done to the meter nor the equipment being
diagnosed. It may waste some time though.
Figure 7.21