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Voltage test
Unless otherwise specified. Make all voltage tests with the electrical connectors still connected.
Insert the test leads into the backside of the connector and make sure the test lead touches the
electrical wire or metal terminal within the connector housing. If the test lead only touches the wire
insulation. There will be a false treading
Always check both sides of the connector as one side may be loose or corroded. Thus
preventing electrical flow through the connector. This type of test can be performed with a test or a
voltmeter. A voltmeter gives the best results
1. Attach the voltmeter negative test lead to a good ground (bare metal). Make sure the part used
for ground is not insulated with a rubber gasket or rubber grommet
2. Attach the voltmeter positive test lead to the point to be tested
3. Turn the ignition switch on. If using a test light. The test light will come on if voltage is present. If
using a voltmeter. Note the voltage reading. The reading should be within I volt of battery
voltage. If the voltage is less. There is a problem in the circuit
Voltage drop test
The wires. Cables. Connectors and switches in an electrical circuit are designed to carry
current with low resistance. This endures that current can flow through the circuit with a minimum
loss of voltage. Voltage drop indicates where there is resistance in a circuit. A higher than normal
amount of resistance in a circuit decreases the flow of current and cause the voltage to drop
between the source and destination in the circuit.
Because resistance causes voltage to drop. A voltmeter is used to measure voltage drop
when current is running through the circuit. If the circuit has no resistance. There is no voltage drop
so the voltmeter indicates 0 volts. The greater the resistance in a circuit. The greater the voltage
drop reading.
To perform a voltage drop:
1. Connect the positive meter test lead to the electrical source (where electricity is coming from).
2. Connect the voltmeter negative test lead to the electrical load (where the electricity is going).
3. If necessary, activate the component(s) in the circuit. For example. If checking the voltage in
the starter circuit, it would be necessary to push the starter button.
4. Read the voltage drop (difference in voltage between the source and destination) on the
voltmeter. Note the following:
a
The voltmeter should indicate 0 volts. If there is a drop of 0.5 volts or more. There is a
problem within the circuit. A voltage drop reading of 12 volts indicates an open in the circuit.
b
A voltage drop of 1 or more volts indicates that a circuit has excessive resistance.
GENERAL INFORMATION
TEST PROCEDURES
NOTE
If using a test light. It does not make any
difference which test lead is attached to
ground
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