In this video I will be comparing the data speed of scan tool and a labscope using the throttle position sensor. There is a misconception in my field, that a scan data graph is fast enough to catch glitches and drop-outs in a signal.

I will also show you ways to speed up the data on a scan tool by limiting the amount of data parameters (PIDs).

Engine Performance Diagnostics chapter 7

test shown enh 50

  • sweep test of a TPS using scan data
  • how to speed up a scan data graph
  • sweep test of a TPS using a scope

Tools used

  • lab scope
  • scan tool

end faq

Playlist

(Chapter 7) Potentiometer-position sensor tests TPS, EVP, APP, VAF etc

Related videos:

Throttle Position Sensor Test (voltmeter and scope):

Hesitation and idle problems from a bad TPS (OBD1 Eclipse) :

How to test a throttle position sensor (P0121, P0122) GM wiring integrity :

end faq


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!

 

You have no rights to post comments

Comments   

0 #2 ScannerDanner 2017-12-14 13:23
Quoting Guest:
Paul, If I am testing a GM AAP sensor it should be the same as a TPS because it is also a potentiometer., correct. So if I am using a scope I would have to use two channels because there is 2 separate circuits in that sensor if I am understanding it correctly. So I would go to each signal wire of each circuit and piggy back the grounds ? Then do sweep test and look for abnormalities between the two circuits ? Thanks

Yes, that is correct! Just be aware that your APP and TPS signals 1 and 2 will look different from each other. One may go high as the other goes low. One may have half the amplitude and yet another (TPS 2 on some GM's) will have intermittent drop outs in the signal which are normal! The 5v ref 2 circuit carries these same "drop-outs" for some diagnostic purpose. Crazy the first time you see it.
0 #1 Guest 2017-12-14 12:35
Paul, If I am testing a GM AAP sensor it should be the same as a TPS because it is also a potentiometer., correct. So if I am using a scope I would have to use two channels because there is 2 separate circuits in that sensor if I am understanding it correctly. So I would go to each signal wire of each circuit and piggy back the grounds ? Then do sweep test and look for abnormalities between the two circuits ? Thanks