Diagnose Electrical Accessories

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Diagnose Electrical Accessories

• It is easy to diagnose electrical accessories
• If you can read wiring diagrams

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Quiz 20
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• Blower Motor works on HIGH only
• What might cause this?

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Warning Systems

• Most systems will ground a buzzer or warning lamp

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Gauges

• Explore the operation of a bimetallic dash gauge

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Bimetallic Gauges

• As voltage increases what happens to amp flow?
• Many dash gauges use anInstrument Voltage
  Regulator (IVR)to keep a constant 5 volts to the
  gauges

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Diagnose dash gauges

• Notice if all gauges are out or only one
• Use a test light to ground the sending unit wire
• Do not use this technique with digital dash

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Two Coil Magnetic Gauges
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Three Coil Magnetic Gauges
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Diagnosing Gauges

• Some gauges can be damaged by grounding sending
  unit wire
• Digital Dash gauges may send 5 volt reference to
  sender
• Use diagnostic charts to diagnose digital gauges

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Instrument Clusters

• Use caution when handling printed circuit boards
• Finger prints can cause high resistance and
  eventual open circuits in printed circuits