Body Electrical System CHAPTER 40 Body Electrical System

Introduction Electrical systems are becoming more complex. Addition of electronic and accessory systems

CAN-Bus System (1 of 3) CAN and bus are used together. Sensors and control modules share info. Several network layouts/designs

CAN-Bus System (2 of 3) Principles of operation Uses binary data Networks transmit and receive signals.

CAN-Bus System (3 of 3) Configurations and terminal resistors Vary with manufacturer Resistors connected internally/externally

Testing the CAN-Bus System (1 of 14) Trouble codes indicate fault. Reading requires diagnostic tools. DLC breakout box allows access to terminals in DLC. May need to be disconnected

Testing the CAN-Bus System (2 of 14) Using a scan tool Many different types and brands Ignition may need to be on without engine running

Testing the CAN-Bus System (3 of 14) Check for module communication errors with scan tool. Multiple modules Connect CAN-bus DLC and compare findings to service info.

Testing the CAN-Bus System (4 of 14) Performing software transfers, updates, or flash reprogramming on electronic modules May require software transfers Flash program tool may require ignition system.

Testing the CAN-Bus System (5 of 14) Electric accessory motors Rotate from magnetic fields

Testing the CAN-Bus System (6 of 14) Motor types—brush, brushless, permanent magnet, and stepper type Motors perform specific functions. Brushless DC motors do not have brushes. Stepper motors rotate in fixed sets through degrees.

Testing the CAN-Bus System (7 of 14) Blower motor and circuits Permanent magnet type

Testing the CAN-Bus System (8 of 14) Cooling fans and circuits Common Contain battery or power supply

Testing the CAN-Bus System (9 of 14) Power mirrors Permanent magnet motors Dynamic braking critical

Testing the CAN-Bus System (10 of 14) Power windows Permanent magnet motors Mechanical arrangement varies. New systems improve safety/usability.

Testing the CAN-Bus System (11 of 14) A circuit diagram for electric windows.

Testing the CAN-Bus System (12 of 14) Power seats Standard on modern vehicles A circuit diagram for electric seats.

Testing the CAN-Bus System (13 of 14) Electric height adjustment of control pedals Adjusts brake and accelerator

Testing the CAN-Bus System (14 of 14) Testing electric motors Motors wear and fail.

Horn Systems (1 of 3) Horns warn others of presence Must have working horn within sound levels

Horn Systems (2 of 3) Horn, relay, switch, clock spring Sound from vibration of metal diaphragm Switch in steering wheel

Horn Systems (3 of 3) Testing the horn system May fail in many ways Test power first. Test horn relay.

Power Door Locks (1 of 6) Common operation installed in each door Integrated with security system Use electrical actuator Solenoid-type has permanent magnet.

Power Door Locks (2 of 6) Electric lock and keyless entry systems Separate systems

Power Door Locks (3 of 6) Two common types of systems RKE PKE

Power Door Locks (4 of 6) Principles of operation RKE has a fob transmitter and receiver inside vehicle. PKE has electronic key.

Power Door Locks (5 of 6) Testing electric locks Fail for many reasons Consult system’s wiring diagram.

Power Door Locks (6 of 6) Removing door panel Remove door parts.

Wiper/Washer System (1 of 5) Important safety system Ensures clear line of sight

Wiper/Washer System (2 of 5) Wiper and delay circuits Three speeds High, low, intermittent Ground-switched circuits

Wiper/Washer System (3 of 5) A wiper circuit diagram.

Wiper/Washer System (4 of 5) Testing the washer system Test both electrical and pump discharge circuits.

Wiper/Washer System (5 of 5) Testing the wiper system Can fail for many reasons Presents crush injury hazard

Heated Glass, Mirrors, and Seats (1 of 3) Temperature differentials cause condensation. Heated glass reduces moisture. Heated seats provide passenger comfort.

Heated Glass, Mirrors, and Seats (2 of 3) Low- and high-voltage systems Draw a lot of electrical current

Heated Glass, Mirrors, and Seats (3 of 3) Testing heated accessories DVOMs and test lights

Cruise Control Systems (1 of 7) Provide convenience for driver Standard accessory Cruise control. A. Electric. B. Vacuum.

Cruise Control Systems (2 of 7) Wiring schematic for cruise control.

Cruise Control Systems (3 of 7) Types of systems Aftermarket/OEM

Cruise Control Systems (4 of 7) Principles of operation Compares actual speed to target speed

Cruise Control Systems (5 of 7) Electronic throttle control Cruise control integrated into engine control system

Cruise Control Systems (6 of 7) Active cruise control Active or dynamic

Cruise Control Systems (7 of 7) Testing cruise control system Depends on type

Supplemental Restraint Systems (1 of 15) Installed passenger safety device Manufacturers develop and improve airbags

Supplemental Restraint Systems (2 of 15) Purpose and operation of SRS Protect occupants Seat belts secure and restrain. Airbags deploy in severe accidents.

Supplemental Restraint Systems (3 of 15)

Supplemental Restraint Systems (4 of 15) Airbag and pre-tensioners Some countries mandate seat belt Airbag often in center of wheel Two types airbag triggering mechanisms Electrical and mechanical Electrical current triggers squib.

Supplemental Restraint Systems (5 of 15) A. Driver’s side airbag B. Passenger’s side airbag.

Supplemental Restraint Systems (6 of 15) C. Side airbag D. Knee airbag

Supplemental Restraint Systems (7 of 15) Mechanical airbags do not have electrical circuitry.

Supplemental Restraint Systems (8 of 15) Airbag is composed of nylon. Pedestrian airbag is new.

Supplemental Restraint Systems (9 of 15) Seat belt pre-tensioners Tighten seat belts in severe frontal accidents Mechanical systems rely on inertia. Rip stitching is used on seat belts. Replace belts once ripped.

Supplemental Restraint Systems (10 of 15) Sensors, control module, and circuitry Sensors are installed in various positions. Side-impact airbags are located on door sills or B-pillar. Front collisions deploy driver and passenger airbags.

Supplemental Restraint Systems (11 of 15) Sensors, control module, and circuitry (cont’d) Safing sensors prevent incorrect and unnecessary deployment. Capacitors store electricity. Seat-mounted airbags work without electricity.

Supplemental Restraint Systems (12 of 15) Smart airbag technology Safety devices improved

Supplemental Restraint Systems (13 of 15) Diagnosing SRS Can be dangerous SRS lights = fault code stored in memory

Supplemental Restraint Systems (14 of 15) Proximity sensors Safer parking Backup cameras and displays

Supplemental Restraint Systems (15 of 15) Proximity sensor. Back-up display.

Entertainment System (1 of 8) More refined and complex Accessible and affordable

Entertainment System (2 of 8) Types of systems Basic to expensive

Entertainment System (3 of 8) Principles of operation Incorporated into network Communication between devices Audio controls on central control pod or head unit Music plays from several sources. Speed-dependent volume Viewing screens

Entertainment System (4 of 8) Diagnosing entertainment system Many functions in one

Entertainment System (5 of 8) Satellite communication Thousands in orbit Tracking system works without satellite.

Entertainment System (6 of 8) Triangulation/trilateration GPS relies on 24 satellites. RF signals travel far. Info forms 3D pyramid. GPS knows apex. Satellites use solar energy. Affected by weather conditions

Entertainment System (7 of 8) Satellite navigation Mapping software generates overlay map. Allows accurate and reliable navigation Program compares vehicle position info. Has many features

Entertainment System (8 of 8) Telematics Two-way communication Vehicle tracking and security Service to customers

Anti-theft Systems (1 of 7) Prevent unauthorized use of parts Many technologies

Anti-theft Systems (2 of 7) Types of systems Prevents entering, starting, driving

Anti-theft Systems (3 of 7) Component identification Deters theft Uses microdots

Anti-theft Systems (4 of 7) Vehicle locking Improved door locks Dead locking Keyless systems Remote key and computer info exchange Remote fob/keyless entry

Anti-theft Systems (5 of 7) Engine and transmission immobilization Prevents engine starting/stopping Transmits/receives coded info Uses rolling codes Fob buttons transmit RF signal.

Anti-theft Systems (6 of 7) Alarms Siren/horn sounds. Monitor for unauthorized entry

Anti-theft Systems (7 of 7) Diagnosing anti-theft system Controlled by BEM Computer controlled with self-diagnostics

Summary (1 of 3) Electrical systems are complex. CAN-bus and bus describe data sharing network in vehicles. Diagnosing and repairing may require software updates. Electric cooling fans for radiator are common. Power mirrors use permanent magnet types.

Summary (2 of 3) Electric windows use permanent magnet motors. Horns sound from vibrations of a metal diaphragm. Technicians need to know how to service all accessories. Wiper and washers are important safety systems. Drivers program a target speed in basic cruise control systems.

Summary (3 of 3) Cruise control systems are active or dynamic. Safety systems protect occupants. Seat belt pre-tensioners tighten seat belts. Crash sensors can be installed in various positions. GPS relies on at least 24 satellites. Automotive telematics combines two-way communication and information.

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