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Here is an entertaining scenario: what if the vent solenoid is partially shorted -- still works, but consumes, say, 1.5A instead of 0.5A. And the driver in the FPCM is over-current protected at 1A, turning off the load quickly and trying again shortly after. This would get the solenoid not working, and the 4A light bulb dimly lit, even though nothing is wrong with the FPCM driver in this scenario. Not saying that happened in your case, but something to be aware of as more and more circuits in modern cars receive over-current protection.
Great video. It also pushes home the reason why I still drive my 1998 Chevrolet K1500 and 1998 K3500 trucks. Not being able to get a module for a four year old vehicle is nuts.
Great video Mario. Only other thing I would have added is to verify the vent valve resistance is correct in case it is pulling too much current and caused the damage to the FPDM. Corrosion is the most common cause but still worth checking the load amount. I’m tired of these parts being unobtainable as well. Imports older than 1995 are getting hard to find parts for and domestics vehicles newer than 2010 are hard to get parts for. We are waiting for TCMs, Ecoboost VCT gears, blower motors, wiper motors, tundra fuel pumps and the list goes on.
@@alinduta5398 the manual won’t give specifications for inductance but will give specification for resistance. Most vent valves are 20-40 ohms from what I’ve encountered.
Nice video. I work at a GM dealer and we replace these things all the time most of the time we get a p0449, p0498 and p0499. No programming required. 👍🏼👍🏼
good good, does that mean that the parts are backordered for that reason and the dealer gets exclusive access and customers get shafted with longer backorders?
Sadly most flat rate techs won't bother to properly diagnose this correctly the first time, instead they'll sell the vent solenoid, flag the the diag and install time and then when that doesn't fix the problem they request additional electrical diag time. The worst part is that most of the techs who do this are praised for flagging so many hours and making the shop lost of money by upper management
@@howardboyd7764For the customer’s sake / bill . It’s the right thing to do . The mechanic can enjoy the inner rewards such a self respect / peace of mind .
ITS JUST KNOWING YOUR SYSTEMS ,,,,,,,,,, AND TAKING THE TIME TO DO THE TESTING . THANK YOU MARIO,,,, I REALLY LIKED THIS VIDEO I ONLY WISH THERE WERE MORE STRAIGHT FORWARD VIDEOS LIKE THIS IT HELPS WITH REMEMBERING THESE TESTS PROCESS LATER ON DOWN THE ROAD .!!!!!!!!!
Unfortunately a large amount of techs would have replaced the vent valve because "they are always bad", and sent the vehicle on it's way. Load replacement is a great way to actively test the circuit. Too many techs only use voltage and never consider current flow. I would guess if a tech had used a voltmeter instead of a lamp they might have seen power and ground and left it at that.
This is a kick ass video that is clear and very well explained. Thanks for this video! Oh what was that 2 wire lead that you used to bridge those connector pins?
Can I just clear up some confusion in my mind, not yours 😂 you said the FPCU had a permanent 12v and was earth switched by control unit, then you used your 4amp load between the white wire which went from the control module to vent valve and a chassis earth, I take it you used the earth from chassis to load the earth to vent valve but how did you know that the chassis earth was good? Brilliant video, love your explanations
I have some issue in Toyota rav4 2020 (engine coolant bypass valve solenoid2) code (P2681) the full vedio in my channel the problem is highe resistance and caused by the pin in connector of pcm not connecting properly .. good work super mario
Good job, Mario . I've had some of these before . I usually check power and ground to module (at module connector ) . I noticed you skip checking the power(12v) to the module . I'm afraid to skip that step. But from I gather in this video , is that If you have communication to module , no other codes , and command . Then there is to need to test 12v feed to module. I would only test ground supply to module . Correct ?
Correct. Especially since the fuel pump is driven from the driver module, which is at least 6 amps in load. Technically i didn’t have to check the ground to the driver module either. But figured it was an easy enough step to take so i did it anyway
I was told by a gm tech that fuel tank vapor pressure faults will set same vent ckt code also. Reminds me of Ford setting P0340 cam ckt fault and engine mechanical timing is cause, as an occasional example.
I would've checked the resistance of the vent valve to be sure that's not what damaged the module to start with as applying direct power and ground to the valve to test it is not fully testing it, it's only testing the mechanical operation of the valve.
Minimo. Masther. Thank you. For your video for me is a class in it. You have to to teaching in a college. Please. But here in California. Ok. Also a quick question. Where I can buy a tools that you show there the lamp and the connector. Please. And once again thank you 🙏. Gracias Siempre
When testing the component that the computer is commanding it doesn't matter because it's unplugged and while testing the the component measure how many amps it draws so when you test the harness side that goes to the computer you will know how many amps the component uses to operate you don't want to put to many amps in a low amp circuit you will fry the moduel know how many amps the circuit uses to control the component then select the right test light 👍
For giggles i checked Rock Auto, they only had 1 in stock and it was a standard, not a GM part ! And what is going on when a 2019 fpcm is failing ? Crazy
I had to watch this 2x to get my head wrapped around this, and i think i get it now. You would still check for correct B+ to the module, correct? Thank you.
That wouldn’t give us any more information than what we already know. The headlamp had a command, but would not fully illuminate, unloading the circuit and commanding it andand seeing 12v would only tell us that there is voltage drop. Seeing anything between .1-12v would tell us there’s voltage drop. It truly doesn’t give us any more information
@@SuperMarioDiagnostics Thanks for taking the time to answer some of the questions ! It helps our understanding significantly ! I hope you have a wonderful evening Mario !!
It's nuts to be buying a GM vehicle where the module goes bad all the time. Good business for the dealer and mechanics, bad for the customer/owner. Do I need to say anymore?
What about the guys that came on here for that silver bullet and you royally screwed them in the beginning by telling them to replace the vent valve?? 🤣