Description And Operation: Description
BATTERY (1)
A single 12-volt direct current (DC) battery, located in the engine compartment and is the heart of the vehicle's electrical/electronic system. The battery:
- Is fully charged at 12.6 volts
- Allows the vehicle to store electrical energy
- Provides system voltage
- Is a source of current for starting the vehicle
- Acts as a stabilizer for the entire vehicle electrical system
- Provides current to vehicle electrical systems when:
- The charging system is not operating
- Current demands exceed the output of the charging system
Vehicles equipped with the Engine Stop Start (ESS) system will also equip a secondary, or supplemental, battery position next to the cranking battery. The supplemental battery is used in place of the Voltage Stabilization Module (VSM) which allows the vehicle to keep the power accessories functional during a ESS event.
BATTERY CABLES
Battery cables connect the positive and negative battery terminal posts to the vehicle electrical system.
The negative battery cable (4) is attached to the vehicle chassis, which provides ground.
The positive battery cable (3) splices and attaches to the:
- Power Distribution Center (PDC)
- Starter motor
- Generator
PROTECTION DEVICES
Circuit protection devices and/or components are used to protect the circuit in an event of an overload (too much current). Examples of common protection devices are:
- Fuses
- Battery Fuse Terminal (2)
- Fusible elements and links
- Circuit breakers
- Positive Temperature Coefficient (PTC) resistors which are integrated into ECUs and are not serviced separately
FUSES - A new dual circuit fuse known as the Micro 3 is being introduced to several vehicle platforms. The design allows a single fuse to protect two different circuits at the same time. Power is fed through the center terminal and passed to the two outer terminals Though two separate links, each outer terminal connects to a different circuit. If one circuit is overloaded and a link burns through, the other circuit remains unaffected.
Remember the following key points regarding fuses:
- The majority of fuses for the vehicle are housed in the Front PDC
- Cartridge-style or jewel case fuses are typically used for higher amperage circuits
- Blade-type mini fuses are used for lower amperage circuits
- Fuses are color-coded and marked with an amperage rating
- NEVER replace a fuse with one of a different amperage rating
- Blade-type fuses can be quickly tested with a 12-volt test light
CIRCUIT BREAKERS :
- Are typically used to protect electric motors and their circuits from heat damage and overload caused by excessive current.
- Does not have to be replaced as it will reset itself after it cools.
PTC RESISTORS:
- A PTC resistor is typically found in an Electronic Control Unit (ECU) where a fuse does not protect a circuit.
CONTROL DEVICES
Control devices are needed to start, stop, or re-direct current flow. Examples of control devices are:
- Intelligent Battery Sensor (5)
- Switches
- Relays
- Transistors:
- Include High-side Drivers (HSDs) and Low-side Drivers (LSDs)
- Are typically located in modules or ECUs
RELAYS
- Allow low amounts of current to control larger amounts
- Work like an electrically controlled switch that supplies or removes a circuit connection to voltage or ground
- The PDC incorporates 5-pin relays that work the same as a standard relay.