The tests shown in this video can be used for any 3-wire cam or crank sensor. The P0336 code was caused by the crank sensor connector being left unplugged. So rather than just plug the sensor back in and clear the codes, I decided to take this opportunity to show you how to test the crank sensor circuit on this car. (1996 GM 3100)

There are two crank sensors on these early GM 3100 engines. One is a 2-wire magnetic type sensor that GM calls a 7x crank sensor. (7 pulses per 360 degrees of crank rotation). The second is a 3-wire hall effect type sensor that GM calls a 24x crank sensor (24 pulses per 360 degrees of crank rotation). This is the one we will be focusing on for this video.

Engine Performance Diagnostics Chapter 21 pages 20-28

symptoms 50

  • Check engine light (P0336)

fix 50

  • reconnect sensor connector

test shown enh 50

  • how to verify wiring integrity on a pull-up type hall effect using a test light and scan data
  • how to determine hall effect circuit design (pull-up or pull-down) which is critical in knowing
How to perform a proper bypass test:
  • how to perform a hall-effect bypass test
  • how to check powers and grounds to a hall effect
  • what does a digital square wave signal look like on a digital voltmeter
  • a frequency graph compared to the actual signature of the waveform

Tools used

  • lab scope
  • incandescent test light
  • scan tool

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(Chapter 21) Ignition inputs, cam and crank

Related videos:

Hall effect cam/crank sensor tests Part 1 (ScannerDanner Premium lecture):


Hall effect cam/crank sensor tests Part 2 (ScannerDanner Premium lecture):


How to test a crank sensor on a GM 3800 engine (3x and 18x signals):


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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available as an eBook or paper book.

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