This is a great review of section 3 material in my book, specifically about testing a ground side switched solenoid. I kept it simple this time, doing all my circuit checks with just a digital multimeter and test light. Remember that all the methods shown can be successfully applied to ANY ground side switched output.

Engine Performance Diagnostics chapter 3 pages 2 - 19

symptoms 50

  • check engine light (P0443 and P0455))

fix 50

  • replacing the purge solenoid

test shown enh 50

  • how to find the evaporative emissions purge solenoid by following fuel supply lines
  • how to safely T-pin a computer controlled output
  • testing a ground side switched solenoid with a digital multimeter and test light
  • using a bi-directional test to confirm control circuit and driver integrity

Tools used

  • scan tool
  • digital multimeter
  • LED test light

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(Chapter 3) Transistors, Solenoids, Computer Controlled Output Testing

Related videos:

How to test a computer transistor driver (with a scan tool):


How to test a computer transistor driver (without a scan tool):


How to test a computer controlled solenoid (energizing the circuit manually):


How to test a fuel injector circuit with a noid light (a ScannerDanner Premium video):


How to test a computer controlled solenoid - power/ground side identification:


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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!