Evaporative Emission Diagnostic P0446

John Instructor Beaver, Pennsylvania Posted   Latest   Edited  
Case Study
Driveability
Emissions
2005 Chevrolet Cobalt 2.2L (F L61) 4-spd (4T45-E)
P0446 - EVAP System Vent Control Circuit
Cannister Vent Valve
Performance

Here is a video for an evaporative emissions system diagnostic for a cannister vent valve performance code. The key points being how to leverage scan tool functions while making physical changes to the vehicle in order to prove exactly what is going on with the vehicle.

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

Thanks for the very well detailed and very well thought out testing procedure

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Way way too long John. Any case study video should be five minutes max. Think about your target audience. Remember, anyone who misses something can just watch it again.

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John Instructor
Beaver, Pennsylvania
John Default
 

Noted, but don't agree. Subsequent efforts on this subject can be shorter, but the only other way to cover that much information and build this foundation would have been to do multiple video's. I considered it but chose to keep this intact. Diagnostics doesn't fit into some a cookie cutter pattern, learning how to be good it doesn't either.

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

Great reply John, some things just need to be covered in their entirety

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

I think you're missing the boat Geoff. There are dozens of professional automotive diagnostic youtube channels that routinely post videos of 30 min or longer and these get thousands of views. I have watched many of them myself. There are many good ones but here are a couple that have some of the largest subscriber bases. There is a ton of quality stuff here but it's just the tip of the

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
   

Missing what boat? I have watched every video both of those guys have made. Watching Eric Obrocta bang on a ball joint for twenty minutes is not a diagnostic case study, nor is watching Paul Danner lecture on injector driver theory.. Long videos for the youtube audience at large and good diagnostic case studies are two different things. A good diagnostic case study is five minutes max. With

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John Instructor
Beaver, Pennsylvania
John Default
 

Hmmm. Five minutes. I'll give you all of the material that I have for the Nissan Frontier no start, no communication that I worked through last year. Let's see you produce a good diagnostic video for it that only runs five minutes. FYI. You'll have about twenty seconds for each issue. This was a lighthing strike that had two people into it before I got it and they only succeeded in adding more

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Nobody learns anything from a lightning strike repair except you shouldn't try them John. You would do a series of short ones for something like that. People making videos need to remember the rest of us are watching them in our SPARE TIME.

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John Instructor
Beaver, Pennsylvania
John Default
   

That's what pause and time stamps are for. One of the first things that had to be figured out was a code that was setting in the BCM for ignition switch power mismatch. The silver bullet answer to just that one problem was that the IPDM was fried (it was the third one that had been installed) because of a wiring harness connection error from one of the previous repair attempts. There is no way

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default
 

Yes, indeed, you have just proved it would NOT BE a good case study. Convoluted ridiculous fff-ed messes do not generally make good case studies. If it's far too big a mess nobody can follow along. In your case you could just title-splash "AFTER THREE FRIED IPDM, we found THIS" and you show where the wires were ruined by the last guy. Of course then you are just bashing another shop and that's

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John Instructor
Beaver, Pennsylvania
John Default
 

There were no wires ruined. A wiring harness had to be disconnected inside of the power distribution center in order to get the IPDM out. The body of one of the connectors for it was identical to one that actually plugs into the IPDM, and the two connectors were cross connected. If I do the video, it's going to have to show all of the vehicle issues noted on the first step of the examination…

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Anthony Student
Hudson, Wisconsin
Anthony Default
 

John, couldn't agree more. you are targeting an audience that is particular to this kind of training. don't change a thing.

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

John, your last paragraph here says it all. The important thing is not so much "what" fixed it but rather, how did you go about figuring it out. Do you remember the Diagnostic Donut books by Bill McGrath? I still have one from the mid 90's and it was really a book full of silver bullets. At the time, they were very useful since cars of that era did suffer from a lot of pattern failures…

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default
 

Personally I don't watch any of the ball joint type videos. I dislike it enough when I do it so i dont want to watch anyone else do it. I pick and choose different diag videos because I like seeing the thought process employed in ferreting out difficult and intermittent problems. I have definitely learned a few things from those guys and I can handle more than 5 minutes too. ;-)

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