Join me and one of my students at RTC as we troubleshoot an intermittent no start problem on a Jeep Grand Cherokee. The procedures shown in this video apply to all Chrysler, Dodge and Jeep electrical systems. In particular, the cam and crank sensor tests that we show.

Engine Performance Diagnostics chapter 21


  • intermittent no start, no spark or injector pulse
  • check engine light on P0320, P1391 trouble codes
  • hesitation and surging

fix 50

  • replace faulty crank sensor

test shown

  • how to test for cam and crank signals on scan data
  • what scan data Ignition Cycles can be used for
  • how to test the cam and crank sensors with a scope
  • how sample rate of a scope affects the signal
  • why a sensor ground is better to use than battery ground in some circumstances
  • how to recreate an intermittent problem
  • sensor power and ground tests

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(Chapter 21) Ignition inputs, cam and crank sensors

Related videos:

Picoscope Basics Part 1:


Picoscope Basics Part 2:


How to test a crank sensor (Chrysler Dodge Jeep):


Jeep 4.7 no start from faulty cam sensor (an SD Premium video):


Faulty cam sensor setting a crank sensor code - P1389, P0320, P0622:


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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.

Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium. There is a 14 day free trial.

On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!