1. 1 Automotive Electrical Systems R. Bortignon

2. 2 Electrical Circuits Contain 4 main parts… 1. Power source  battery  alternator

3. 3Load 2. The load in a circuit is the part that does the work  load will always have some resistance  this resistance can be measured

4. 4Control 3. The control is what turns the load on or off…  opens & closes the circuit  may be installed on the ground side or the power side of circuit

5. 5Path 4. The path are the wires that connect the battery & alternator to the control and load devices in a circuit  frame/body of the vehicle is a path for the ground circuit

6. 6 Circuit Protection to protect the vehicle’s electrical system from excessive current flow, fuses are usedto protect the vehicle’s electrical system from excessive current flow, fuses are used  fuses open the circuit if current (amperage) levels exceed a predetermined level

7. 7 Types of Fuses cartridge fusescartridge fuses blade type fusesblade type fuses  mini size  standard size  maxi size  mega fuse ceramic disc fusesceramic disc fuses  see info on next slide  replace fuses with correct amperage rating!!!

8. 8 Positive Temperature Coefficient Fuses  PTC fuse technology utilizes a polymer-based material to protect electrical circuits from excessive current.  During normal operation, numerous carbon paths within the polymer allow the device to conduct electricity.  As current through the PTC fuse reaches its rated threshold, the polymer material begins to heat causing the polymer to expand.  The resulting expansion breaks the carbon chains to reduce the current through the circuit to a small leakage current.  The increased resistance in this resettable fuse works to protect circuitry by limiting potentially damaging current.  When the fault (over-current) is removed from the circuit, the PTC fuse will reset itself thereby allowing current to flow through the circuit again.

9. 9 many older vehicles use glass cartridge fusesmany older vehicles use glass cartridge fuses

10. 10 Fuse Panel Locations can be located…can be located…  under left side of instrument panel  in the engine compartment  many vehicles have fuse panels in both locations

11. 11 Fusible Links special wire that breaks & opens a circuit when overloadedspecial wire that breaks & opens a circuit when overloaded insulation bubbles, melts & opens to expose wireinsulation bubbles, melts & opens to expose wire usually connected near the battery & feeds the fuse box(es)usually connected near the battery & feeds the fuse box(es) must be replaced with correct ratingmust be replaced with correct rating not all vehicles use fusible linksnot all vehicles use fusible links  modern vehicles use maxi fuses instead of fusible links

12. 12 Circuit Breakers some circuits such as power windows & power seats use circuit breakerssome circuits such as power windows & power seats use circuit breakers circuit breakers reset themselves when current levels are back to normalcircuit breakers reset themselves when current levels are back to normal  (do not need to be replaced like fuses)