Home Sensors Distributor Hall Effect Type Used to show Engine Speed and Cylider Recognitionr
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Distributor Hall Effect Type Used to show Engine Speed and Cylider Recognitionr E-mail
The Hall effect type Distributor Provides the speed and the cylinder potion of the engine. This type of Distributor replaced the earlier Points type Distributor.
 
  • The Hall effect sensor is a simple switching circuit. The circuit is switched by a hall chip. The Hall Chip is located adjacent to a magnet and a drum mounted to the Distributor shaft rotates between the magnet and sensor. There are cut outs in the drum that allow the magnet to trigger the hall sensor. When a cut out passes between the magnet and the Hall sensor the magnetic field influences the Hall sensor. When a solid part of the drum passes the Sensor the magnetic filed is removed from the sensor. It is this action that produces the on/off switch. This signal is interpreted by the ignition module, Ignition control unit or Ecu as a square wave.

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  • The sensor has 3 terminals marked +, - and 0  The + terminal is the Ecu to Sensor supply voltage. This will generally be 5 volts. The - terminal is the earth connection and should read 0 volts. The 0 Terminal is the signal voltage which is a square wave. The frequency of the signal increases with engine speed.

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Testing with a Voltmeter: As above the Sensor supply voltage can be measured and will normally read 5 volts. The earth connection should so 0 Volts. The Signal voltage is a bit more tricky to read. It will give an Ac voltage reading but ideally should be measured with an oscilloscope. See below

Testing with an Oscilloscope:

 

Measurement taken with a Pico Automotive scope


The Signal is measured from the center pin. The frequency of the signal will increase when the engine speed increases.

If no signal can be measured check the power supply and Earth terminals. A symptom of this sensor failing is the vehicle can run fine until hot, when the sensor breaks down. When left to cool the engine will start again.