A4 Quattro Wagon L4-1.8L Turbo (ATW) (2000)
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A Complete Circuit
Four things are required for current to flow in any electrical circuit, and for that circuit, and for that circuit to function as intended:
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Power Source (Voltage)
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Conductors (wires, printed circuits, etc.)
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Load or Consumer (a user of electrical power)
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Complete Circuit (a connection to ground)
Open Circuits
An open circuit is an incomplete circuit. An open circuit occurs when some kind of malfunction interrupts the circuit path and prevents current
flow. Some common causes of open circuits are:
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Broken wire
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Loose or disconnected connector
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Loose or damaged connector terminal
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Corrosion
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Malfunctioning fuse or component
Test for an open circuit by checking continuity using an Ohmmeter (multimeter), or by checking for Voltage at various points of the circuit using a
test light or Voltmeter (multimeter). See Checking Wiring and Components.
Short Circuits
A short circuit is an unintended complete circuit. A short circuit occurs when some kind of malfunction causes current flow to follow the wrong
path.
A short circuit to ground (GND) (grounded circuit) may prevent Voltage from reaching a component. If Voltage is shorted directly to ground
(GND), bypassing any load, the unrestricted current flow will damage fuses wires or components. Some common causes of short circuits are:
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Damaged wire or wiring harness
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Malfunctioning insulation
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Internally damaged component
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Incorrect connection
Test for a short circuit to ground (GND) using a multimeter or a test light to indicate circuit malfunctions and abnormal current flow paths. See
Checking for Short Circuit to Ground (GND).