1. Body Electrical System
CHAPTER 40
Body Electrical System

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

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

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

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

6. 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

7. 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

8. 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.

9. 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.

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

11. 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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

46. Supplemental Restraint Systems (3 of 15)

47. 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.

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

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

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

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

52. 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.

53. 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.

54. 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.

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

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

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

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

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

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

61. 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

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

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

64. 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

65. 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

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

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

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

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

70. 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

71. 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.

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

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

74. 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.

75. 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.

76. 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.

77. Credits
Unless otherwise indicated, all photographs and illustrations are under copyright of Jones & Bartlett Learning.