Input Sensors and Actuators On-Vehicle

4.0 RPM Sensor or Crank Position Sensor (CKP):

4.1 Located the RPM sensor or crank Position sensor for the vehicle or engine you are working on.

4.2 With the engine Not Ruining , back probe RPM signal wire by inserting a pin down the rubber insulation far enough to connect with the metal wire terminal on the inside.

4.3 Setup the voltmeter to read AC volts. Attach meter red lead to the pin; attach black lead to a good ground. Make sure the meter leads are clear of moving parts for when you start the engine. 

4.4 Make sure all students are clear of the engine. Start the engine.

4.5 Record the reading from the meter: 3.90 v if you do not get a reading on the meter, you may have to check for a good connection, or try another wire. Turn off the engine when you switch to another wire, then restart the engine and check for a reading. Try different wires, or get help from your lecturer until you get a good reading to record above.

4.6 Increase engine RPM to about 2500 rpm. Record the reading from the meter: 07-13 v

4.7 Return the engine to idle speed. Switch the voltmeter to read DC volts. Record the reading from the meter: 0.70 v.

4.8 Increase engine RPM to about 2500 rpm. Record the reading from the meter: 1.30 v. Return the engine to idle speed.

4.9 Switch the voltmeter to read Hz. Record the reading from the meter: 650.5 Hz. (Some MAF sensors output is a Hz signal, some is an analogue voltage signal)

4.10 Increase engine RPM to about 2500 rpm. Record the reading from the meter: 1.60 KHz. Return the engine to idle speed, and shut off the engine.

4.11 Which setting best showed if the RPM sensor was working AC volts DC volts AC or Hz Hz.

What type of RPM or Crank sensor is on your engine?

4.12 Describe how this type of RPM or Crank sensor works:

This is AC generator when rotating the distributor generates on AC voltage which increases in frequency and amplitude. This is only for the inductive type, but if the sensor is optical or hall effect the frequency will change with speed but the amplitude will stay the same.

4.13 Discuss how using different functions of your meter can help you to accurately measure the sensor output when you don't have an oscilloscope available?

AC voltage helps as it changes the speed or rotation of distributor but DC voltage does change but not too different. so we are looking at the voltage changes of the rotation or speed.

4.14 What can go wrong so the ECU did not receive the correct signal from the RPM or Crank sensor:

If the computer does not receive the correct signal from the RPM or Crank shaft sensor, the engine will crank but it will not start.