1. Computer Control

2. Computer Control Basics Input – (Sensors) Processing – (Black Box) Output – (Actuators)

3. Computer Sensors Voltage Producing Sensors Variable Resistance Sensors Variable Voltage Sensors

4. Voltage Producing Sensors There are two common types used in vehicles and equipment Variable Reluctance Sensors Hall Effect Sensors

5. Variable Reluctance Sensors These sensors often measure Rotation They create their own A/C voltage They have many names but work the same …Magnetic Pulse Generators …Pickup Coils …Reluctor Sensors

6. Variable Reluctance Sensor Uses a Reluctor that moves past a coil of wire wrapped around a magnet. As the reluctor moves the magnetic flux lines, A/C voltage is induced in the coiled wire. It uses 2 wires and create it’s own voltage Senses speed and position of rotating objects

11. Missing teeth identify crankshaft position Other teeth measure RPM Output Shaft Position Sensor

12. Hall Effect Sensors

14. Digital sensor Uses 3 wires positive voltage, ground and signal voltage Senses speed and position Can sense very slow rotation speeds

17. 3 wires Power Ground Signal Magnet Hall Effect Switch

19. A/C Analogue Signal Notice position locator D/C Digital Signal Notice position locator

20. Variable Resistance Sensors Thermistor Variable Resistor Rheostat Stepped Resistor

21. Thermistor

22. Variable Resistor

23. Variable Voltage Sensor Potentiometer Switches Fancy Magical Electronic Sensors

24. 2 volt Potentiometer Used as a sensor

25. 4 volt Potentiometer Very low current

27. Switches (Pull-Up) Biased Low (Signal wire should read ground volts when unplugged)

28. Switches (Pull-Down) Biased High (Signal wire should read system voltage when unplugged)

30. Computer Actuators Relays Solenoids Stepper Motors Indicator Lamps and Display Panels

31. Relay

33. Solenoid

36. Normally Closed Solenoid

37. Normally Open Solenoid

39. Stepper Motor Used to control a specific position Air Vent Cruise Control Gauges Control Module will “Count” the steps to know what position the motor is in

40. Stepper Motors

41. 6 steps higher

42. 2 steps lower

43. Computer Networks

44. Understand the CAN-BUS Electrical System CAN stands for Controller Area Network This allows all the computers (controllers) to “talk” to each other on one set of wires BUS refers to a common wire Computers talk to each other on a Network where each Controller shares the same voltage signals at the same time

45. What Language do computers use? Digital ON - OFF …. High - Low … 1 - 0 Binary code is either 1 or 0 known as a bit 8 bits in a Byte How many bits in a Kilo Byte? Mega Byte? Giga Byte? Terra Byte?

46. Computers talk fast! Hertz Hz Mega Hertz MHz Giga Hertz GHz

47. How do computers talk? Voltage High – Low On – Off

48. What messes up the Communication? Open Circuits Short Circuits EMI (Electro Magnetic Interference)

49. What Causes Electro Magnetic Interference? Radio Waves Electrical Current moving in nearby wires

50. How can you avoid EMI? Twist the communication (BUS) wires Use a grounded metal shield that surrounds the BUS wires to absorb the energy of moving magnetic flux lines

51. 120 

52. How can you test for Opens or Shorts in the CAN-BUS? Use an Ohm Meter Should read total parallel resistance of CAN terminals 1 & 2

53. 120 

54. Why do computers need to talk? More than one computer may need vital information

55. How do you fix Computers? Look for proper sensor input If the sensor input is incorrect, test the sensor and wires Look for actuator commands If the actuator does not respond test the actuator and the wires