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How to Check a Hall Effect Sensor With a DVOM

Hall effect sensors are circuit components made from semiconductors. They produce voltages that are proportional to the magnetic field near them and are used as detectors and switches. They are found in the camshafts and ignitions of cars. Hall sensors have three leads: supply, ground and output. The output is only on the range of millivolts. To check the output of a Hall effect sensor with a DVOM, also known as a digital volt-ohm meter, connect the instrument's probes between the sensor's ground and output. Move a magnet around to test it. Use a metal object to help test the sensor if it is inside of a car.

Things You'll Need

9V battery
Alligator clips
10K ohm resistor
Magnet
12V battery
Steel gauge or knife

Instructions

IC Chip Test
- 1
  Identify the supply, ground and output leads on the sensor. Attach the supply lead to the plus side of the 9V battery, and the ground lead to the minus side of the battery. Use alligator clips, if necessary.
- 2
  Attach the left side of the 10K resistor to the sensor's output lead, and its right side to the positive side of the battery. Connect the black probe of the DVOM to the left side of the resistor, and its red probe to the other side.
- 3
  Place the DVOM on a DC setting. The display will show a constant voltage. Move a magnet back and forth near the sensing area, which may be very small. The display will show fluctuations on a millivolts scale.
Automotive Sensor Test
- 4
  Connect the plus side of a 12V battery to the sensor's supply lead. Connect the minus side of the battery to the sensor's ground lead.
- 5
  Place the DVOM on a DC setting. Connect its black probe to the sensor's ground lead, and its red probe to the sensor's supply lead.
- 6
  Insert a knife or steel gauge between the magnet and sensor. When the metal touches the magnet of an undamaged sensor, the DVOM will display a change that is within 0.5 volts of the battery. When the metal is removed, the DVOM will show a change less than 0.5 volts.

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