Electrical Accessories

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Olivia Preston
5 years ago
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1 Electrical Accessories Power accessories are designed many different ways Always use a wiring diagram to figure out how your system is designed Wiring diagram will allow you to decide how and where to test the system

4 Windshield Wipers Windshield wipers use an electric motor and linkages called the transmission. The transmission wiper linkages turn rotary motion to the back and forth of the wiper blades

6 Two speed windshield wipers Wiper motors use an off set brush for high speed Off set brush causes the armature to generate less Counter ElectroMotive Force (CEMF) Armature is the spinning part of the motor With less CEMF generated, the motor spins faster

7 OFF

8 Low Speed

9 High Speed

10 Low Speed

11 Two speed windshield wipers The windshield wiper switch directs current to the low speed brush, or the off set high speed brush Directing current to the offset brush will increase the windshield wiper motor speed

12 controlled by armature Park switch

13 Wiper Motor Park Switch The park switch will prevent wiper blades from stopping in the drivers vision when turned OFF The park switch is mechanically moved as indicated by the dotted line connecting the switch to the armature

14 controlled by armature Park switch

20 Wiper Motor Park Switch The wiper motor armature has a flat spot that allows park switch to ground only in the park position. Park position is with wiper blades at the lowest part of the windshield When windshield wiper switch is turned OFF the wiper motor will continue to run until the wipers are at the lowest spot on the windshield

21 Off Off

22 Low Speed

23 Low Speed

24 High Speed

25 High Speed

26 High Speed

27 Switch OFF Wipers UP (not park)

28 Switch OFF Wipers Down (Park Position)

30 Parking Wiper Blades Wiper motor can reverse directions Slots in the transmission linkage will pull blades down lower than normal travel when the wiper motor is reversed This is done to hide wiper blades from driver view when in Park position

31 Off Position

32 On - Low speed - Top brush is ground

33 On - Low speed - Park switch cycles

34 On - Low speed - Park switch cycles

35 On - Low speed - Park switch cycles

36 ` OFF Top Brush Positive Motor reverses direction Wipers will Park in lower than normal position

38 Gauges Explore the operation of a bimetallic dash gauge As more current flows through bi metallic gauge it heats up and bends to show high pressure (oil pressure gauge) high temperature (engine temperature gauge) full gas tank (fuel gauge)

39 COLD High resistance

40 HOT Low resistance

41 Gas Tank Sending Unit Empty High Resistance

42 Gas Tank Sending Unit Full Low Resistance

43 Bimetallic Gauges As voltage increases what happens to amp flow? Many dash gauges use an Instrument Voltage Regulator (IVR) to keep a constant 5 volts to the gauges

47 Diagnose dash gauges Notice if all gauges are out or only one Use a test light to ground the sending unit wire Test lamp will flash as instrument volt regulator operates Do not use this technique with digital dash

49 If only one gauge is bad, suspect sending unit or wires to the sending unit

50 If all gauges are bad, suspect problem common to all gauges (fuse, IVR if used, ground, printed circuit of dash panel)

51 If only one gauge is bad, suspect sending unit or wires to the sending unit

52 If all gauges are bad, suspect problem common to all gauges (fuse, IVR if used, ground, printed circuit of dash panel)

53 Gauges with 2 wires will be bi metallic sing an instrument voltage regulator. These show high with more current and low with less current. Gauges with 3 wires will be magnetic. 3 wire magnetic gauges can show high OR low as current increases

54 If all gauges are bad, suspect problem common to all gauges (fuse, IVR if used, ground, printed circuit of dash panel) 3 wire gauges use two or more coils to form opposing magnetic fields that will move the gauge needle. Instrument voltage regulator is not needed as changes in system voltage will affect both magnetic coils equally

55 If all gauges are bad, suspect problem common to all gauges (fuse, IVR if used, ground, printed circuit of dash panel) Two Coil Magnetic Gauges

56 High resistance in sending unit

58 Low resistance in sending unit

59 Three Coil Magnetic Gauges Sending unit works Opposite from other gauges

60 High resistance in sending unit

62 Low resistance in sending unit

63 Diagnosing Gauges Sending unit is most common cause for one gauge to become inoperative To confirm a bad sending unit locate the unit

64 Diagnosing Gauges Gauge should go full travel high or low (depends on style of gauge) Ground sending unit wire with test lamp Gauge should go to other side of travel If gauge changes it proves gauge and wires are good and replacing sending unit will fix gauge

65 Diagnosing Digital Gauges Electronic controls can be damaged by grounding sending unit wire Use diagnostic charts and scan tool to diagnose digital gauges Scan tool can often confirm operation of digital gauges (functional test)

66 Instrument Clusters Use caution when handling printed circuit boards Finger prints can cause high resistance and eventual open circuits in printed circuits

67 Speedometers Changing tire size will change calibration (cause speedometer to become inaccurate) Different size drive gears are available to correct for tire size and differential ratio Digital speedometer can be re flashed to accept larger or smaller tire diameter Tires other than stock sizes can cause problems with transmission and brake controllers

68 Optional Type Accessories Heated Windshields Uses alternator at high voltage While windshield heats all alternator output is directed to windshield Runs close to 100 volts

71 Heated Back Glass Operates at normal charging system voltage Most common problem is open circuit in heater grid

72 Power Windows/Seats Use of wiring diagram is critical to diagnosis Slow turning motors will cause increased amp draw Check for binding mechanisms Self re setting circuit breaker protected

74 Warning Systems Most systems will ground a buzzer or warning lamp

Diesel Technology: Electrical and Electronic Systems

Diesel Technology: Electrical and Electronic Systems NATEF Crosswalk The following NATEF Electrical/Electronic Systems tasks (rev. 2001) are covered in this publication. The chart shows where each task