Do you ever feel overworked

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Do you ever feel overworked?

• Your vehicles electrical system can feel the same
  way.

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Circuit Protection
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The three types of circuit defects are

• Shorts to ground to voltage
• Opens
• High Resistance
• poor connections

C75-78 L64-71
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Short to ground

• A short to Ground Means that we have a path to
  ground before the load. This will cause extra
  current to flow and will burn out the fuse or
  blow the circuit breaker. (copper to steel)
• The only time this is not true is when the short
  is the control side of a relay. Then for example
  on a horn circuit, the horn will sound.

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Short to ground
Wire touch or rubbing up against the wire causing
a fuse to blow and the light not going on.
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Shorted

• Another form of short to ground is a relay or
  motor that is shorted. Take a look at the relay
  if a wire connects between 85 and 86 bypassing
  the load it will blow the fuse.

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Short to voltage

• A short to voltage usually happens when two wires
  of different circuits come together and touch.
  For example a taillight and a brake light wires
  could be touching and the brake light would be on
  whenever the lights are on. (copper to copper)

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Short to voltage
Light switch is off but light is still on because
a hot wire is touching the wire and feeding 12
volts of electricity to the wire.
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Opens

• An Open circuit is were there is no connection.
  I usually refer to this as (cut copper) because
  nothing can get through. Can happen on positive
  or the ground side of the circuit. A broken wire,
  blown fuse or a switch in the off position can
  cause this.

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Opens
Wire is Broken
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High Resistance

• Connections not touching properly Could be loose
  or paint not cleaned off or a build up of
  corrosion. (green copper) This could cause a
  light to be dim or a blower motor to be slower
  then normal.

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High Resistance
You lose voltage going through every connections
12.6 volts
8.2 volts
Corrosion, paint or a loose connection will not
allow allow all the electricity thru the
connection.
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Fuse boxes

• A fuse box can be located in several different
  locations can be under the hood, under the dash,
  in the trunk or somewhere in the circuit.

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Toyota Fuse box
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Fuses (Page C52 )

• Glass Cartridge (Old Cars)

How to pull them
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Two reasons for blowing

• Where do they blow?

Why?
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Fuses Ceramic Glass

• Rated by current failure level
• Three letter code for type and size (SFE AGC)
• Glass style replaces ceramic
• Caution in pulling

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Fuse types
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Fuses (Page C52)

• Auto-fuse (blade type) ATO /ATC
• Mini-fuse
• Maxi-fuse
• Test holes
• Pulling

MAXI ATO/ATC MINI
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GBC Fuses
GBC Fuses for European cars Older cars like the
VW Beetle
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Maxi-fuses

• Combination blade / cartridge
• Protects main circuits
• Safer than fusible link
• Cover fewer circuits than a fusible link
• Often in Power Distribution box

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Fuses
Male Pal fuses
Female Pal fuses
Bolt on Pal Fuses
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New Circuits
?

• What size of fuse should I install?

Page L53
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Fusible Links

• Lighter gauge wire than main conductor
• Covered with special insulation
• Protect Main circuits
• Usually under hood

C54-55 L53-54
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Fusible Links

• Insulation
• Visual checks
• dont work
• Installing a new link
• Size 4 wire sizes smaller (4 numbers larger)
• Soldering

C54-55 L53-54
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Circuit Breaker

• Why circuit breakers
• Styles
• Deterioration

C56 L55
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Circuit Breakers
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TESTING CIRCUIT PROTECTION DEVICES

• Must inspect closely
• Type of failure determines cause
• Best to use DVOM
• Do not overload circuit by installing to large of
  fuse or tin foil
• Connections must be tight
• Do not use un-fused jumper wire

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TESTING FUSES

• Best to use DVOM, Test light can be used
• Power must be flowing to test
• Some Fuses are hot all the time
• To check the others the
• Key must be on
• Lights must be on
• And some cars it must be running to check some
  fuses like the charging fuse.

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TESTING FUSES

• Must check each side of the fuse.
• Must have power on both sides.
• If neither side has power you need to find out
  why? Turn on key! Turn on Lights! Turn on dash
  light controls! Turn on engine! Etc
• If only one side has power you have a Blown fuse
  replace with the same size.

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End of circuit protection