2008 Chevy Avalanche EVAP Vent Solenoid Test (P0449, P0455)

This is a good review of some of the material in Section 3 of my eBook and video lectures.
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Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

[@ozzstars_cars]

Saturday night, smoking a cigar, having a beer and watching your videos.....life is good (cause i'm married with kids and over 40 yo) :-). Excellent detailed explanation on the purge solenoid!

[@Macmillium]

Abnormal = using logic and research to troubleshoot and resolve problems. It takes time, talent and effort to be at this level of reasoning. It saves the use of unnecessary replacement of parts and gives the satisfaction of learning this art. So, thank you for your abnormality...

[@danielgarcia9095]

You're a great instructor you explain everything in a simple understanding way thank you you're awesome and thank you for sharing your knowledge with all of us we really appreciate it

[@JahanZeb1976]

Excellent video with excellent easy to understand testing procedures. Nice work.

[@toyotatechMDT]

Another great video Mr D. I enjoy the 'Do as I say, not do as I do!' You capture your students attention really well, great teacher.

[@ScannerDanner]

Thanks man

[@mikecont9742]

Great step by step video. Thanks for taking the time.

[@briangutierrez5635]

thank you for replying back to me and for your videos I follow your steps and double check and it works. And now the check engine light is gone on

[@serena12195]

i want to thank you, it is well done, by the way this valve is located under the spare tire for people like me that thought that is was close to the tank.

[@hmroa3056]

Thank you! This is very helpful for me. I am having this same EVAP issue and this helps me understand what I am looking for AND to recognize the results of my testing.

[@ScannerDanner]

That's why I do these my friend. Thank you! Good providence too

[@contagiousFX]

you have great students. makes it much interesting to learn.

[@stevensilva1350]

You're a good teacher.

[@defaultname3125]

HI Paul, Thanks once more for the informative videos. There are none better for in depth "how to" or "why this is" anywhere. I am a premium subscriber and have your eBook. I just wished I had an instructor like you back when. God Bless

[@ScannerDanner]

+Gulf Coast Auto Repair thanks brother!

[@gerryr8400]

Thank you for this video cause this is the truck I'm working on and issue I have of vent staying open and not closing. I subscribe to your site.

[@angelonicassio7131]

You’re a good teacher :)

[@mike-yp1uk]

I love the book. Best bang for the buck. It will hyper-link you to a specific video to really sink it in

[@ScannerDanner]

Thank you mike!

[@FinallyOnRecords]

Loved ya video hopefully this helps me

[@lAdrianl]

I knew it!!!! God I loved this video!!!! I had soo much fun watching this!!! And just graduated from uti last Friday!! Boy I say I'm pretty smart!! Amazing video man!!!!!

[@TyWeMc]

Very good information.

[@HOOSH69]

Paul, u are slicker than a peeled onion(that means pretty smart, in hillbilly terminology) lol After months of frustration and a couple solenoids and o rings and cussing, and beer... I find this video from some link i was reading about 3am(seriously debating which method I was gonna use to "have an accidental electrical/fuel related fire" and rehearsing my story/extremely shocked and innocent appearance when the fire department and insurance guy showed up), and next thing I know I'm debating which method I'm gonna use to repair the "half broken internally/intermittent" white wire in the harness under the cab... I had just practiced so hard being super distraught and lucky to be alive after "the fire" I was about to have, that I was almost unable to feel happiness and closure during my 5am test drive/trip to Walmart for more electrical tape to secure my harness loom. Lol. Thanks a ton! Sincerely: a NORMAL person..

[@hddm3]

thanks paul

[@johnnation6187]

Definitely not ghost voltage, but good guess. You should use the Load Pro test leads on this exact scenario or any other wiring/electrical issues. It will simplify the explanation. Good video, very informative.

[@sam111880]

O ok so uses the od2 tool to close it or put power to it correctly to close it or using vise grips with hoses over them and clamping vent off .. all set thank you great video

[@mohammedbassam7923]

you are the best🔧🔧

[@jesusmalagon4336]

thanks danner

[@michaelszweda]

could you please do some video on gm a/c door actuators tests and some type of values I change a lot due to duel a/c systems blowing warm air thanks

[@aimeekunst3379]

after changing out vent solenoid code p0449 keeps coming back on have and more ideas what would cause that code to come back on

[@amoreholliday]

I would like to know, should I Replace The tip of the wire, or the solenoid? I have a visible vapor leak, unsure of whether the wires are damaged or the solenoid

[@TheSchadenfreuda]

It seems as though it would be easier to see if the solenoid itself is bad before checking the wiring, by removing the electrical connection and applying 12V to the solenoid to see if it is operational (clicking)?

[@michaelbarry8005]

21:28 I have a set of 'noid lights that are a much safer way to check harness integrity than twin back-probing with a clumsy incandescent test light. The last P0449 I had was on a Silverado, and I punted it because the vent was jammed directly below the crevice between the cab and the bed, in an awkward location that was made much more awkward due to the huge pile of fresh horse sh!t piled into the crevice directly on top of it.

[@TheBucktowncrazy]

Question I have a 2007 GMC YUKON XL with 3 codes 0455 which is saying a bad leak. What exact part do I need to buy to change it. thanks

[@joejordan5879]

I have a loZ setting on my DVM to cancel out ghost voltages.

[@ernestocavazos4507]

Hi, I have a chevrolet malibu 99 and have problems with vent selenoid and purge selenoid I check fuse and both selenoid are good and checkselenoid with voltage external, sound click selenoid my question is: need some pressure for operate the drivers in PCM or only with the turn on the key must be operate the drivers and send the ground to both selenoid. Or this symptoms are bad PCM ? how to force to send ground to selenoid throug the PCM

[@gbowne1]

EVAP Leak Test P0455 is the video on P0455 and another on P0449... EVAP Code P0449

[@jregal100]

I have a 02 avalanche with p0336 with really rough idle and cuts off any ideas I’ve already switched the crank and cam but still same problem code no misfires at all

[@carlnickell412]

What's the posibility thst the plug has some corrosion in side of the plug causing that 5mill Amp voltage reading off of the othier lead that has 12v to it

[@rhkips]

Yes Paul, your methods are different. Us "normal people" don't have $40k worth of diagnostics equipment. Though most of us also very much wish we did. ;-D In regards to the P0300 on this vehicle, I noticed the scantool mentioned "DTC set since last cleared" or something to that effect. Has someone else been in there before you guys? If nothing else is readily apparent for the random misfire code, check vehicle history, see if it got a CKP sensor recently. If it did, put the truck through a Crank Variation Relearn. You may have to do it over a dozen times before it takes. I've seen this problem on GMs way too many times. The factory flowcharts will tell you that replacing the sensor may cause misfires NOT to be properly monitored, but at no point will it ever say that false misfires could be detected. I find the latter to be the case more often than not. Just some thoughts on direction if nothing else makes itself apparent. :-)

[@jeffreymuller2294]

Great lesson... I have 12 volts on both wires (as I should) but the voltage doesn't drop on the ground when I command the purge valve open. I'm thinking the ground wire is damage somewhere back to pcm or the pcm driver is bad. Does this sound correct? BIG THANK YOU for a response!!!

[@ScannerDanner]

Agree! I've never seen one of these computer drivers go bad. A few things to consider. 1. If there is a hard fault (happening right now) for the vent valve circuit, this can prevent your bi-directional test from working. So clear codes and see if it sets immediately. 2. Measure the same control wire at the PCM. If it is 0v, you definitely have an open in the harness. If it is 12v, then we focus on the driver. 3. Tug on the harness wires right at the connector of the vent valve. They break inside of the insulation.

[@smileyrod11]

HEY DAN WEAR DID YOU GET T PIN TOOL LET ME KNOW THANKS

[@EvendimataE]

would it matter if the wires going to the solenoid are reversed? say the connector has to be replaced and accidentally wired the wrong way

[@kevinjarrells4385]

good info here. on your premium channel do you have any case studies on evap flow fault diagnosis. or possibly honda civic evap systems?

[@ScannerDanner]

Not at this time.

[@stuntmotorsport]

whats the name of this software your using.?

[@jimmyhat1122]

With ignition on: i have 12v (red wire) 0v ( white wire). What should I look for now?

[@cesaralvarado515]

Good

[@scottsennsibaugh885]

I can't put gas in my Avalanche the pump cuts off like it's full but gas gage only moves for the amount of gas I can get in it which isn't much but not showing any fault codes?

[@mrexecutive1]

Do you have to command the vacuum cut valve solenoid open on Asian vehicles, when doing smoke test so that smoke can reach the tank area? that style of evap system is tricky.

[@ScannerDanner]

+mrexecutive1 not sure man

[@pepperjack8]

That 0.5 volt is due to high input impedance of the computer. Just think of 2 resistors. High resistance of bad solenoid and smaller resistance of the computer. When on, the computer pulls the input to ground. Any smaller voltage than 0.5v is due to resistance of system wiring

[@enddrenalinerush2059]

Had a gross leak p455 on my 07 Aspen,was the fuel filler neck .now I have a p456 code for small leak.i smell gas after I shut the car.its using alottttt of gas.please help!

[@kevinreed8707]

Great video! I replaced my solenoid before finding this video. I still have the same code. When I check the voltage i always have 12v key on or off, truck running or not. It's a constant 12 volt on both sides, like the ecu is not sending the ground. What would cause this? 2008 silverado 5.3

[@MTBAlex]

I'm having the same issue, did you ever resolve the problem?

[@angelonicassio7131]

What if the control circuit is bad? New wire?

[@gailtaylor1636]

A quick voltage test is to stick a noid light in the vent electrical connector and turn solenoid on/off with scanner.

[@ScannerDanner]

Good one Gail!

[@gailtaylor1636]

ScannerDanner I should have said circuit test. So far my OTC noid light kit hasn't let me down, as for having one to fit. The only objection that could be raised is we normally try NOT to disturb the wiring/connectors just so we don't miss an issue. Just moving a connector around might temporarily "fix" a problem. But in this situation, the vent solenoid is probably THE most frequent failure, so I don't worry about that happening. It's a habit to closely inspect any connector for damage/corrosion anyway.

[@NomadicMars]

Great video. I have a question though. I am using a Mac tools logic probe and I have power on the 12v rd/wht supply wire, but I am not seeing a ground or 12v signal on the white driver wire. I suspect I have a wiring issue or computer issue, what are your thoughts?

[@ScannerDanner]

get rid of that logic probe and use a regular test light. Most likely your solenoid winding is open. you will not see a ground on the control wire unless you are commanding the driver on with a scan tool. And you will not see "power" unless the winding is good and the driver is off. (It's not really power on that control wire which is why I don't like logic probes)

[@NomadicMars]

ScannerDanner Thank you. I have a simple code reader and I no longer own my Snap-on MT 2500 scanner and cannot command the driver to cycle on and off. I had assumed with key on I would see the white wire show ground as the computer cycles a command. Once again great video and thank you for the help.

[@jesusmartinez-wq9hk]

How many olms should the solenoid have if it's good?

[@randalusa]

This is kind of obvious, but I would like to know for sure. The insets showing what is probably a Verus there, does that unit have ability to record long screenshots (several minutes in another upload viewed yesterday), from which you add them to your video and sync to the camera shot of you working?

[@ScannerDanner]

For sure, it is a windows based laptop (The Verus). I can record the screen for as long as I need. I've had some over an hour.

[@randalusa]

+Danner - I am surprised the hard drive and processor is able to capture live for so long. My laptop pitches a fit if going even less. Makes my at some point acquisition of a Verus all the more enticing. I already concluded a used eBay model for price (around $1200) is just better than the alternatives because of the scope and extra info provided by Snap-on that helps in diagnosing. That's where the thinking is heading at this point at least. Your video and reply helped me discover an unexpected addition to the features. Thanks.

[@benafluck]

The one that you are reading is voltage inductance.

[@EzRepairs]

Hi danner need big help 2005 Nissan sentra cannester vent valve p1446, 2 wires ground swith,when plug in power on both connectors unplug only on one, when plug in I did the test light test connected to ground, back proveing the ground side valve did not work, i remove the valve from the car and run straight 12v valve worked did the same test out of the car giving 12v on the power side and ground with the test light Valve did not work, I did the same test on the purge selenoid on and out of the car and it work both ways, I'm just confuse as why this happens, my theory its that the selenoid has to much resistance that it requires full power to work, hope you can help as I don't want to replace a good working part, thanks

[@nickrivetti5219]

so how exactly do you fix the code

[@mrkttrdr2919]

gettimg the 449 code my 05 coly, its got 171,000 on the clock, cant complain, didnt expect it last this long, this is my go to vid for testing, thanks for posting, are u still teaching? or did u give that up

[@ScannerDanner]

Yes I am, just not the day to day classes. Got a class coming up May 16th for 4 days at my school

[@Rosman1974]

P0440 on my 2010 Chrysler Town and Country

[@EMENDOZA2000]

Can you please upload more oscilloscope sample videos. And what would u recomend buying the ebook or the pdf book.???

[@EMENDOZA2000]

I ment e book or the printed book

[@ScannerDanner]

They both have the same content. It would be personal preference. The eBook is Web based so you must have Internet connection however the advantages are you can access it from all your devices. If you wanted something to take notes on while watching my page for page lectures on my premium channel, go with the paper version. Thanks!

[@Phix1964]

Question... How does the computer determine if the solenoid actually closes? Does it use a pressure sensor somewhere else in the system to determine that? If so what sensor? Thanks in advance.

[@ScannerDanner]

+Kevin Finn It doesn't monitor this solenoid directly (mechanically speaking). The only time it is closed is during a leak test and if it doesn't close, the PCM will flag a large leak fault. The system is monitored with a pressure sensor mounted on top of the fuel tank sending unit. For the leak test: -PCM opens the purge valve and closes the vent -once vacuum builds in the system, PCM shuts off the purge and keeps the vent closed, while watching the psi sensor for a decay in vacuum

[@MyJonyo]

Is there a way to test any of this without a 4,000 dollar scan tool. My 07 impalla threw the 0449 code. I have replaced the old vent solenoid and bench tested the old one wich was deffinetly bad. However the check engine light on the dash remains.

[@generalmotors327]

you have to reset the ecm providing the problem is fixed the light will go away

[@littlebeargaming8267]

Hey, Mr Paul. How would you be the computer and turn on and off the vent solenoid? I do not have a scan tool that can command the valve on and off.

[@ScannerDanner]

+littlebear gaming disconnect it and run your own power and ground to it. Post here for additional help. www.scannerdanner.com/forum/post-your-repair-questions-here.html

[@littlebeargaming8267]

Sweet ! Thank you, Mr Paul. Just to let you know ,I am addicted to your teachings.

[@gregpratico656]

I have been working on a buddies car for a couple of days on this same issue. My buddy had replaced most of the evap parts before coming to me for help include the vent solenoid. So the vent is new. After hours of testing I found out that the solenoid was not getting power so I checked for brakes in the wire. I was able to actually run completely new wire from the main harness new the computer where I found power to that wire. I ran wire from the feed and the ground and actually was able to get the vent to command on and off using the scan tool. I then cleared the code and I had figured I fixed the job. About a day or two later the code came back on so I told my buddy to check the connection making sure it still got power and it did. The code eventually went back off but then on again after most likely another drive cycle. The hot wire is getting 12v all the time and the ground wire seems to be functioning properly. Is it possible that if the ground wire isn’t functioning probably the vent valve could be stuck close (not being able to open while driving the car) and that trip the code back on? I’m at a lost for words on how the power is function properly to the vent and still throwing the code? I really enjoyed this video and if there’s anyway I could get some feedback on my situation or suggestions on what you would look at or go about fixing this problem

[@ScannerDanner]

You need to find the break in the original wire, I bet the control wire is messed up in the same lo location

[@briangutierrez5635]

I am helping a friend he got the check engine light P0496. how many times do you have to replace this part is it so often

[@ScannerDanner]

Brian Gutierrez What is the definition of the P0496? Yes, the vent solenoids go bad on these all the time.

[@ItsMe-bl4wm]

“Ghost voltage” 😱

[@jasonmohoska1352]

would i go about a P0446 the same way as the P0449. Solenoid is good. Applied 12 volts to it and it closes. With solenoid disconnected i have no voltage to connector with key on. 99 Mitsubishi eclipse gs-t spyder.

[@ScannerDanner]

Yes, you need power to that solenoid. Here is a link to a sight that you can get the same diagrams I use. www.eautorepair.net/marketing/html/about_us.asp?VID=&Count=Y

[@jimmyhat1122]

Can the solenoid fail, or stick in the closed position? Which would not show a large leak code. It would not allow system to vent, and not allow gas tank to fill properly. What would the ohm reading be through the solenoid if it failed in the closed position?

[@ScannerDannerPremium]

Ohm reading will be unaffected and yes they can stick closed.

[@caseyanderson1297]

when I did this test I had the same .5 v in the same situation you did. if it helps

[@kalbert68]

DAN ?! I have a p0449 (2007 Tahoe 5.3) Vent solenoid is Good. Ground signal IS provided by PCM (term 61 if I remember correctly) but not reaching to vent solenoid connector. Any suggestions where to check first for open ? (connectors etc.). Thanks !

[@ScannerDanner]

+kalbert68 sorry man, wish I did. Oh and my name is Paul :)

[@kalbert68]

+ScannerDanner OK Paul:) , thanks !keep up the great work.

[@EricAlan101]

Great video! thanks for the knowledge, Help me fix code p0455 in 30 min . And really help me understand what evap vent valve and solenoid are and what they do. Thank you

[@ScannerDanner]

+EricAlan101 thank you!

[@sebeher09]

I have a 2007 suburban but a cant fix I try to see how to check the white wire from the computer to see if is the wire or the pcm I need wiring diagram from this suburban but I can't get the wiring diagram help.

[@ScannerDanner]

+severo hernandez search Mitchel1DIY, you can get the same diagrams I use for about $20 for your vehicle

[@greenspiraldragon]

I have the vent valve solenoid failed. No system leaks. I replaced the vent valve solenoid and it came back again with a brand new part. What to do next?

[@ScannerDanner]

Tug on the vent valve wiring connector, right at the plug. The wire is broken inside of the insulation.

[@greenspiraldragon]

I will check it thanks.

[@justinallen9014]

What computer program are you using and can you send a link for me get it

[@ScannerDanner]

Here is the DIY version of the program I'm using eautorepair.adtrk.biz/?a=10817&c=24&p=r&s1=

[@ScannerDanner]

The professional version (ShopKeyPro or Mitchell-On Demand) is about $160 a month

[@Timmmmayg4787]

Long shot here. 2003 Chevy blazer. Have 12 volts while using multimeter at plug as soon as it’s plugged in volts drop out. Verified white wire to solenoid has continuity and not shorted from ecu to solenoid. Verified two vent valve solenoids tested good. Tried to bidirectional test with scan tool and had no ability to complete test. Would you say the ecu is bad?

[@ScannerDanner]

You are saying the 12v supply wire is dropping to 0v? This absolutely is not an ECM issue. You have a damaged/corroded supply circuit. To confirm, for me, since I'm not there. Your 12v wire, does it drop to 0 with a test light connected too?

[@Timmmmayg4787]

@@ScannerDanner wow thank you for responding. I dig into it more and found a bad wire. Thank you again for answering a random comment.

[@ScannerDanner]

​@@Timmmmayg4787 I knew you would! Awesome. I love answering those who actually are doing testing. The silver bullet seekers I ignore

[@TheCogleymike]

Same issue here. I have replaced the front purge valve, the vapor canister with harness, and the gas cap. All GM parts, And still have the check engine code? P0449 any thoughts?

[@ScannerDanner]

What about the Vent Solenoid?

[@ScannerDanner]

The P0449 code is related to the Vent solenoid itself or the wiring going to it. Tug on the solenoid wires right at the connector. They are known for breaking inside of the insulation.

[@TheCogleymike]

ScannerDanner I have replaced the vapor canister vent valve solenoid( the long hose with the valve that the harness connects to) and the harness too[ actually some one already did the upgrade to the New were version already]. I also installed the new GM gas cap, in the front purge valve that's located where the spark plugs are. Still get code p0449, i'm trying to do this in my driveway I'm not a shop nor mechanic but I've done a few engine and transmission swaps so I know what I'm doing.

[@TheCogleymike]

ScannerDanner i've noticed on the actual connector itself there's a red wire and a white wire, do you know if each of these wires correlate right to the other, seems when you connect the plug the red and white wires crossed paths,

[@TheCogleymike]

Like it would seem that the Redwire would connect to the red wire and the white wire would connect to the white wire, but because of the clip on the harness and where the plugs fit in the red wire connects to the white wire and the white wire connects to the Redwire. Very odd.

[@williamcalvert7901]

It would have been nice if you showed us where the vent valve is located.

[@ScannerDanner]

Underneath the truck, near the canister for all vent valves on all cars and trucks. Sorry, I typically do

[@sonidofuriamusikal]

im have a gmc yukon 2007 and the code po442 EVAP small leak whats the mean can you help me

[@ScannerDanner]

+sonidofuriamusikal not really, you have a leak that needs to be found with a smoke machine. Do you live near Pittsburgh PA? I can do it for you at my school for free. The two most common causes on GMs with a leak is the vent solenoid sticking and or a bad gas cap. But there are other causes too

[@sonidofuriamusikal]

im live in piittsburg ca thanks for your help

[@jnmoney1986]

couldn't you have just unplugged the solenoid? hooked the volt meter to both wires and actuated the solenoid and looked for 12V?

[@IMFDB]

Hypothetically let's say you didn't have access to a thousand dollar smoke machine and bidirectional scan tool and this same truck did have a gross evap leak code. Could you jerry rig a device to test it? Such as, attach a jumper wire from a good ground on the car to the white wires ground switch to close the vent valve. After the systems sealed could you like take the evap test ports schrader valve out and have a friend inhale a cigar and blow it into the test port while you try looking for smoke coming out in a line. Just a theory I thought i'd ask if you want to fix your evap and your on a tight budget.

[@ScannerDanner]

For sure! But from a guy that its taken 20+ years to finally give up nicotine, that isn't the way I would do it. :) My brother has a rigged up tool he uses for evap. tests. He uses shop air (small amount) and soap and water. (I think) You'll have to ask him. Have you seen his channel yet? James Danner is his KZbin channel name.

[@bstceltics4]

Can i do this while cycling the key if i don't have the computer program to switch it on and off

[@ScannerDanner]

no sir, the conditions for the computer to turn on the vent solenoid are not met by cycling the key or even starting it up. But you can test the vent solenoid without having the computer turn it on. Energize it yourself and see what it does. I'm not sure if I showed that process on this one, but I know I have in other GM vent solenoid case studies that I've done

[@bstceltics4]

@@ScannerDanner I replaced the vent solenoid but my check engine light is still on i wanted to check the wiring to make sure it was getting the appropriate signal to turn on and off

[@ScannerDanner]

Tug on the wiring harness right at the vent solenoid connector. The copper wires break INSIDE of the insulation right by the connector. It will literally pull apart when you tug on the wires.

[@bstceltics4]

@@ScannerDanner i will try it when im done work hopefully its a simple fix

[@gbowne1]

The 2001-2009 GM's seem to have a lot of P0400-0499 series codes. Something with the design of the EVAP??

[@Blazer02LS]

The solenoids get vapor on them, then dust gets in and they stick open. Very common. Really handy if you have a service bay test for EVAP on the scan tool.

[@gbowne1]

Anything to help the solenoid keep from getting stuck?

[@Blazer02LS]

not really. the location and design are such that they cause issues. IF you scrapped the factory part and used a better part it would stop the problem, but $$$$

[@gbowne1]

yeah, that's usually the case.

[@vernwhite568]

It’s a evac canister I have the po455 code

[@b4322558]

dan I have a 2000 chevy 1500 5.3 w the codes p0171 p0174 p0300 p0449 as well would the vent valve solenoid circ cuse the other codes to fellow as well bc its got new plugs and wires as well and clean the mass air flow and the codes came back and haven't done anything w the vent code as of yet

[@ScannerDanner]

The P0449 code will NOT cause the lean codes and misfire that you have. Totally separate

[@b4322558]

thanks......I got under and tound the big hose off going to the soiled vent vavle cirurt ......ithe misfire and lean codes come back what would u say to look into as to what is coseing the random misfire and lean codes .....I check the fuel presser and it was at 55 psi

[@b4322558]

I saw this vieo just before this ....if u have more vidos mybe that u think mite help let me know thanks so much

[@ScannerDanner]

Jim B start here Using fuel trim and freeze frame data to determine type of lean condition

[@b4322558]

thanks

[@AAA-br3cs]

If we plug vent valve line then what will happen?

[@AAA-br3cs]

And why vent normally open?

[@ScannerDanner]

You won't be able to fill your gas tank

[@dans_Learning_Curve]

Great ground side switching example! Nice back probing probe. They should make them adjustable length so shorting of dual probes doesn't happen. You could also put some shrink wrap on the prob and just have 1/2" showing. No, you're NOT the normal person! LoL You're more fun! "Normal" is an average of a group of people trying to be the same. You're trying and SUCCEEDING in producing automobile techs who can think on their feet and not just be a flowchart robot! Also, a GREAT man can say "I was wrong"! What a great example for your kids and students! "We might be over killing this" You're teaching! Nothing can be overkill with teaching! Keep it up! A long jumper wire from the battery ground would solve the rusty underbody. Just snap it on before going under. You'd have a positive ground. (or would that be a negative ground? LoL~!) I did this when I was field testing my fuel pump on my 98 Windstar. Field testing = in the rain on the side of the road. (That wasn't fun!) My test equipment: paperclip, long speaker wire, and a interior light to serve as a test light. I found an open fuel pump, meaning the brushes weren't conducting to the commutator. I pulled the cover off of the fuel pump relay and used something to keep it closed to provide power to the pump. (instead of the couple of seconds of power with the key turned on) I went under and hit the tank. I could hear the pump turn on with one hit, and turn off with the next.

[@ScannerDanner]

Nice! Thanks so much

[@franksgarage8551]

2010 avalanche, p0449. Testing at solenoid, no change of state. Proved the ecm is not providing ground. Will not illuninate a test light bulb. It grounds enough to make bulb glow. I was suspicious as it works when ambient temp is below freezing.

[@ScannerDanner]

Do the same test at the PCM itself to rule out a wiring issue. My money is on the wiring right at the solenoid connector

[@franksgarage8551]

@@ScannerDanner well, i’m impressed! Quick response. I tested at ecm. That was my first test as i ohm tested wiring. Which was good. It woks perfectly at temps well below freezing. Another indicator of a bad ecu. Guess next test would be to freeze the computer. Why do i always get stuck with these odd failures?

[@ScannerDanner]

@@franksgarage8551 you made it easy to reply as it is clear you don't need spoon fed. I love to help others who can help themselves. If you would have said "I changed the solenoid already, what else could it be?" I'd have kept scrolling lol. Anyway. That is a very weird one! When you did your tests at the PCM did you have the solenoid unplugged? Just thinking about too much current flow from a shorted solenoid.

[@franksgarage8551]

@@ScannerDanner bougt the truck in winter, so no issue until i parked it inside overnight. Went to diag and it had a new evap solenoid. Owner never said boo. Now i know why. I put it aside for the winter, now its spring and i cant stand check engine lights. Diag used to be my thing, typically people send the hard cases to me. But retirement is in the air. Figured i would pick your brain,or maybe for reassurance that i was on the right path. Picking up a used ecm next week, same year same part number.

[@ScannerDanner]

@@franksgarage8551 before you do, make sure current is not more than around 500 ma from that solenoid, or do that test again with the solenoid unplugged with your test light. I've seen drivers enter a current limit mode of amperage is too high and that could make your test light look dim

[@TheAvalanche08]

I replaced the gas cap, the vapor canister & wiring harness (near spare tire) and the vapor canister purge valve (under the hood). I still have the P0449 and the check engine light unfortunately. I cleared the code but it comes back immediately after clearing it. I have no clue what to check next to fix this issue. The code says evaporative emission (EVAP) system, vent valve circuit malfunction. I have no issue filling the gas tank. No issue with the truck. Just can't clear the code. I want to clear this to enable my remote starter.

[@ScannerDanner]

Key on engine off, measure voltage on both vent solenoid wires, plugged in and backprobing. Should be 12 and 12. Start there

[@TheAvalanche08]

@@ScannerDanner Not on the purge valve under the hood but on the vapor canister near the spare tire right? Like you do in the video?

[@ScannerDanner]

@@TheAvalanche08 yes sir, exactly

[@TheAvalanche08]

@@ScannerDanner Great thanks. I'll do this and report back in here with the results.

[@TheAvalanche08]

I have 10,85 on both wires. It’s pretty low, but the key has been in ignition for like 20 minutes.

[@Discretesignals]

Great stuff : ) Don't forget to check for TSBs (09-06-04-028C).

[@jerrym995]

i think he meant "what would normal people do that don't have a $3000 snap on diagnostic code reader"

[@apostmax]

There is no such thing as a ghost voltage. Either there is a bias or a measurement error. 0.5 V is a significant value.

[@ScannerDanner]

Call it what you want, but there certainly is. Watch your voltmeter and don't connect it to anything and shake your leads, you will see a voltage change. It is an open circuit indicator. Sort of a microphone effect. We can argue what it actually is, doesn't matter, as long as you are aware of it and know how to use it to your advantage when troubleshooting is all that matters.

[@apostmax]

@@ScannerDanner I really appreciate that you responded to my comment! Btw I am a big fan and I think you are one of the best (if not the best) in diagnosing cars and teaching others!! I just object to the term ghost. There could definitely be a noisy measurement, however, 0.5V is pretty significant no matter how you look at it; even the poorest multimeter should be able to give a fairly accurate measurement. FYI I have a PhD in electrical engineering. Keep up the good work, we all love your videos!

[@ScannerDanner]

@@apostmax awesome! Great to here from guys like you. Can you give me a time frame in the video where this comment came from? That way I can explain what I was seeing and why it mattered a little better. Thanks!

[@jpol3808]

Just to let you know there scanner danner, I can't afford anything out of my monthly budget, I'm barely surviving as is. I enjoy mechanics even though I don't do it. I do however work on my own vehicles out of necessity as do many of your viewers. I understand the method behind the second part of your videos as salesmanship, in promoting sales to view the second halves of your videos. I also think that those who watch your channel for enjoyment, will now go to somewhere else for that enjoyment and those who will pay for your services, already do. That isn't a very friendly way to do business and sell your channel and in the long run, you also lose word of mouth advertising from the many individuals who watch for fun, because they won't be discussing your channel any longer with their acquaintances. I love your videos but I can't pay and have no real need to pay for them since I don't do mechanic work for a living. That's what your losing versus already having the money of those who want to view part 2 of your videos. Please think of that information for a while. Creating videos and holding the second half hostage is not to friendly and it doesn't show you in a good light that your looking to be seen in. I hope this helps you to decide your destiny concerning this moral issue and the next thing you need to do to continue impressing your fans and putting it the great videos that you do so well. Thanks for listening. It's all anyone can ask for, besides more great videos. Take care bud.

[@ScannerDanner]

This wasn't click bait, nor is there a part 2 of this video. Unless I missed something?? Your opening line "Just to let you know there scanner danner, I can't afford anything out of my monthly budget, I'm barely surviving as is", I was thinking, "oh man, I'm gonna offer this guy free access to my paid channel, just to help him out", then I get to the rest of this and you calling this a "moral issue"?? I have a new upload coming out tomorrow. It's a half an hour video, any idea what it took to edit it the way I do? About 6 or 7 hours. This doesn't include the time it took to film and troubleshoot it. KZbin ad revenue is horrible and is certainly not worth my time alone. So I will continue to market my paid channel on every upload, yet at the same time I have never misled my viewers in any of my videos. Take the recent upload about circuit identification. What did it say in the title and description? What did I say in the video at the beginning? Nothing misleading. Another thing I never do is leave you hanging! Even if it is a multiple part series and the rest of it is on my paid channel. #1, I don't do this often and certainly didn't in this video you are commenting on. And #2, I always make sure I provide good solid material that has takeaways my subscribers can use.

[@ScannerDanner]

Oh okay, I just watched this and your upset because I didn't give you the misfire video on this same vehicle? So you got a FREE how to video on the EVAP system. An absolutely complete, start to finish diagnosis. There was NO part 2, to this problem. I never left you hanging and gave you everything you needed. But your upset because I didn't give you more free stuff? Something totally unrelated. I get it now and I won't be changing anything I'm doing. I still have to feed my family too.

[@ej300k5]

Long story short just replace the solenoid

[@ScannerDanner]

Or learn how to troubleshoot an output device, wiring integrity and computer driver function and start applying those fundamentals to everything.

[@danielgarcia9095]

You're a great instructor you explain everything in a simple understanding way thank you you're awesome and thank you for sharing your knowledge with all of us we really appreciate it