In this video we’re following up on a previous video, in which we found a poor engine ground. This time, we’re using some simple voltage tests on a three-wire pressure sensor to verify wiring and signal circuit integrity. No ohmmeter, wiring diagram or flow charts required! This video can be used to support chapter 8 in my book and the procedures shown can be applied to all types of pressure sensors. (MAP, power steering, transmission, BARO, fuel pressure etc)

Engine Performance Diagnostics chapter 2

symptoms 50

  • check engine light (P0550)

fix 50

  • replace power steering pressure sensor

test shown enh 50

  • using scan data
  • distinguishing between a current (hard fault) and history fault (soft fault)
  • identifying the type of sensor based on the number of wires used
  • how to understand circuit design based on the type of sensor
  • using a scope to test a 5V sensor for supply, signal and ground
  • how to verify your scope connection to a circuit
  • verifying signal circuit integrity with signal voltage fixed low

Tools used

  • scan tool
  • lab scope

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(Chapter 8) Pressure Sensor Testing, MAP, BARO, DPFE, fuel tank and rail pressure sensors

Related videos:

Poor running, flashing CEL, no codes (bad computer ground) - Toyota:


How to test TPS wiring with a scan tool (any car):


How to test throttle position sensor wiring with a resistor (any car):


How to troubleshoot an EVAP Pressure Sensor problem P0452 - GM:


No Start from a shorted MAP sensor (Honda, Acura):


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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!