Electrical Troubleshooting - BMW 1999-2005 M3 Service Manual

Electrical System - General
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Electrical
Troubleshooting
Four things are required for current to
flow in any electrical circuit: a voltage
source, wires or connections to
transport the voltage, a load or device
that uses the electricity, and a
connection to ground.
Most problems can be found using a
digital multimeter (volt/ohm/amp meter)
to check the following:
Voltage supply
Breaks in the wiring (infinite
resistance/no continuity)
A path to ground that completes
the circuit.
Electric current is logical in its flow,
always moving from the voltage source
toward ground. Electrical faults can
usually be located through a process
of elimination. When troubleshooting a
complex circuit, separate the circuit into
smaller parts. General tests outlined
below may be helpful in finding
electrical problems. The information is
most helpful when used with wiring
diagrams.
Be sure to analyze the problem. Use
wiring diagrams to determine the most
likely cause. Get an understanding of
how the circuit works by following the
circuit from ground back to the power
source.
When making test connections at
connectors and components, use care
to avoid spreading or damaging the
connectors or terminals. Some tests
may require jumper wires to bypass
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2/25/2009 11:08 PM