GM EVAP Vent Solenoid Testing
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- เผยแพร่เมื่อ 4 ต.ค. 2024
- 2002 Chevy Silverado 4.8L with a P0449 EVAP system Vent Control Circuit Low trouble code. The vent solenoid on every EVAP system is a normally open solenoid. When the computer performs a leak test, it will close this solenoid. A common problem on GM EVAP vent solenoids is they will stick open and cause EVAP large leak codes. In this particular case we are dealing strictly with an electrical system fault. The information contained in this video will apply to all ground side switched computer controlled devices (solenoids, relays, motors etc)
There were three separate codes on this truck. Here are the videos for the other two codes
How to test a fuel gauge P0463 (thermistor circuit design) - GM
• How to test a fuel gau...
How to troubleshoot an EVAP Pressure Sensor problem P0452 - GM • Pressure Sensor or Pot...
Engine Performance Diagnostics chapter 3
Symptoms
check engine light (P0449 fault code)
Fix
replace vent solenoid (open solenoid winding)
Tests shown
how to test an EVAP vent solenoid
how to determine power or ground side switching
how to perform a circuit integrity test
how to identify circuit design on a wiring diagram
theory an operation of the computer circuitry used to control the vent solenoid
how to test the computer transistor driver
how to command the computer to turn on the vent solenoid
Tools used
scan tool (bi-directional type)
incandescent test light
digital multimeter
back-probing tools
Playlist
(Chapter 3) Transistors, Solenoids, Computer Controlled Output Testing
• (Chapter 3) Transistor...
Related videos
EVAP leak P0455 (vacuum cut valve-bypass valve test) - Nissan
• EVAP leak P0455 (vacu...
How to test an EVAP Vent solenoid (applies to all cars) - GM
• How to test an EVAP Ve...
2008 Chevy Avalanche EVAP Vent Solenoid Test (P0449, P0455) • 2008 Chevy Avalanche E...
EVAP Leak Test P0455
• EVAP Leak Test P0455
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
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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.
![Pressure Sensor or Potentiometer Signal Fixed at 0v [Circuit Integrity Testing]](http://i.ytimg.com/vi/CkgrMasd57s/mqdefault.jpg)
Very knowledgeable and an excellent teacher, gives me great understanding of the when, why and where.
I was a 4x ASE Master Tech until I left the business in 2000. I used to try to explain things like this to other guys in the shop...sometimes, to no avail. Good for you for sharing this kind of diagnostic approach with a far wider audience. Well done.
Thank you Art
Awesome video!! No one could explain it better, more concise, nor thorough
Man!! This guy is good he should be teaching / writing books. Easy to follow step by step test procedure . Do's and do- nots with t-pins. Well articulated tutorial i learn something every time thank you Scannerdanner for sharing knowledge!
@MrMratni Very good comment! And thanks again for the book purchase! You are correct about that test, except in the case of a vent solenoid, I will disconnect the vent hose and connect a long piece of heater hose and blow through the solenoid. (the ports are too big for a hand vacuum pump) De-energized you SHOULD be able to blow through it and energized you SHOULDN'T. GM EVAP vent solenoids are normally open.
Hi ScannerDanner. I know it has been 2 years since we spoke on the issue I was having with a P0446 issue on my 2001 Camaro; but as promised, I have an update for you. I found that the fuel pressure sensor was the cause for the whole problem (The sensor was totally dead). The EVAP system set to ready within 10 minutes of driving after replacing the fuel pressure sensor. Thanks for all the info and assistance that you provided while I was trying to diagnose the problem with that P0446 issue!
nice work! that is exactly the test you needed to do. keep watching it as it flags the code. look for changes. keep me posted. hard to call the computer as being bad
It is what we call a dummy shaft distributor. It is still there to drive the oil pump as the distributor used to do. It will come out. There is a rubber o-ring type seal that is most likely hard as a rock. It is ok to get aggressive with it.
@contagiousFX It is a ground side switched circuit, so with the solenoid open there will be 0 volts all the time on the control wire regardless of circuit activity (driver on or off)
Broski I'm having this problem right now and this video is badass! Thank u so much and learned from this..so I did all the tests and diagnosis and found that at the end it was my original connector that failed.i replaced it and code gone and running good on the truck👍🏽
awesome! Thank you!
your welcome and thanks for the comment
All I can say is Amazing!! This answered all my questions of why there was constant 12 volts at the Solenoid,and it would not operate off the bench and on the truck at idle!! Thanks ScannerDanner..
Thank you Paul for the time to replay and thank for the update of your book.
you heard a click, that's good but you must also check the function of the solenoid. you should be able to blow through it not energized and not be able to blow through it energized. This is a normally open valve so by your description of having trouble filling your tank, either the valve is stuck closed or there is a blockage in the vent line
In addition of after checking the control side and power side of the circuit, you can energize the solenoid with the scanner and apply vacuum with a hand vacuum pump. If the the vacuum doesn't hold then surely the solenoid is bad. Btw, I purchased your book very awesome.
Im the only person who try to clic on the X at 23:00 in full screen? Great video i like it!
No, what I am saying is with the P0446 code not happening (or temporarily fixed), the system was able to complete its monitoring of the system and when it did its check on purge flow it found another problem. So what I am saying is you have two separate issues. IF you fix this P0446 code, you will then continue to set the purge flow code. Unless of course that one is intermittent too.
You need to focus on pins contact at the PCM for that vent solenoid first.
If you energize the solenoid with a test light, that just checks the solenoid and the feed circuit. To test the control wire and the PCM driver you must use a scan tool to turn the driver on or you have to meet the conditions where the PCM will normally turn the driver on. That is the only way. Of course you can use the test light in place of the solenoid for the test, but the driver must be turned on and you cannot do that part with the test light.
You cannot see the control wire voltage on the scanner. At least not yet but that would be cool. I will not be surprised to see output solenoid control wire voltage listed on the scanner in the future. You can see the command on some but that doesn't tell the whole story. Thanks!
first thing is to turn the key on a take a voltage reading on both solenoid wires. I believe this design is ground side switched. so you should see 12 and 12. the result of this test will dictate our direction or next step. Oh and yes you could use a test light to energize this but we are not at that step yet.
no problem at all, glad you fixed it!
You will never hurt a driver with a digital voltmeter.
Thanks for your comments!
@fivefortyeye540i Thanks for the comment and the compliment!
Excellent video - great teaching style.
Thank you for posting.
Excellent diagnosis. Love how you confirmed the integrity of the driver at the end by commanding it on and off. I always like to manually control drivers whenever the option is available. I wonder if maybe you could view the voltage on the control wire through the scan tool, while also commanding it on/off. Of course, it is always important to understand what is going on in a circuit. This vid did that
use a t pin for the pcm connector the make yourself a long jumper wire with alligator clips. be sure to insulate the end under the hood just in case. also use a jumper wire for you voltmeter neg lead too. this way you don't have to hold anything and you can focus on driving
This is one smart mechanic !
Love this video bro thanks. Keep up the great info.
Excellent video. You're a good teacher, you know your stuff, and you use your electronic white board with great proficiency. Keep up the good work.
you sure know what you are talking about!!! very helpful.
sometimes :)
ok, next step is to measure the white wire at the pcm. there should be 12v there too.
Or if you have a bidirectional scan tool, command the vent solenoid on and look for a voltage drop on the white wire.
Because someone else was playing around with this car, I would clear the codes and let the owner drive it until the MIL comes back on. Start with the returning trouble code first.
It is not a leak code. When you see "control circuit" in a code it is either the wiring, computer or solenoid that is at fault. These are known for wiring issues at the connector. Tug on them to reveal a break, sometimes the insulation can even look fine but the wires are broken inside. If you have a voltmeter, with the key on, backprobing the connector (solenoid plugged in) you should see 12v on both wires
ScannerDanner thanks for all the work you put into these videos. I love my Modis scanner a lot more when seeing your videos. You remind me of my tech school engine performance/electrical instructor. question: Does this evap solenoid testing procedure apply with checking an a/c compressor flow valve for a 2008 toyota camry 2.4?
@ScannerDanner capacitors and or despiking resistors that are in a parallel branch to the transistor driver in the PCM. Either way this in no way changes the diagnostic, wouldn't you agree? But it is fun to talk about. You have a great mind.
Paul -- Really Great Information here. All of your videos are big time solid. Sure do wished I lived near your classroom and was 20 years younger ;) Keep on Keepin On. You rock.
+Hawaiian F150 thank you! based on your user name, I wish I lived near you :)
+ScannerDanner Yah man i live on Oahu, Hawaii. From my back porch I can see most all of the leeward side of the island. At least from Diamond Head to Ewa Plains and over to the Waianae mountain range. Of course we can all of the pacific ocean from those points. Great weather here. House prices are pure ridiculousness. We have a 4 bedroom home with about 1800sq/ft but only 5ft to my neighbors property line. Ridiculous for sure but there's only so much room on an island ;). If you want really awesome views and lots of room - your wallet has to have lots of money to waste. And i mean really waste. We're just regular folks so we ain't got that great of a lot. Sure wished I lived nearer to NY or the East coast. I was born in Dorchester MA. Like they say, you don't miss something until it's gone. Sure do miss the snow or perhaps better said; the choice to go out in it if I wanted too ;).Your Videos Are Always Rock Solid man. I am watching all of your videos that I can along with videos from SMA and MotoYama (Ivan's awesome), ETCG, Schrodingers Box, FordTechMakuloco (Brian does amazing things for people all over the America), TIA and a couple others. All of you are exceptionally gifted folks doing amazing things and are extremely helpful with what seems like unlimited Knowledge.I sure do thank you for your hard work and the time you take to share with us. God Bless you and the family! Am sure our father loves your 'on the road' ministry work ;)
+Hawaiian F150 thanks man! even better you sound like a brother in Christ.
May He grant you wisdom in this path your are on and bless you and your family too.
Would you like a coupon for a free month of my premium channel? It's yours if you want it. Email me through my website and mention this.
+ScannerDanner OM Gosh! Ah Yeah ! ;) hehe. You just made an old man smile like a lil kid :) God Bless! Thank You!!
Every driver is different, you have to research the system to know when. .In the case of a GM vent solenoid, the only time it is turned on is during the leak test of the evap system.
Like Paul said you can aggressively twist it with pliers, channel locks or lightly adjusted vice grips. I replaced my 1993 3.1 recently and when you get it out take a knife tip and snap out the o ring. There should be a shaft from the oil pump that may or may not come out with the cap. Mine did. Good luck.
@contagiousFX If done correctly like in this video, it is the best way to test the driver and control wire integrity. Of course you need to understand current flow and that the test light I am using is the same if not lower current than the solenoid carries. There is absolutely no danger to the driver in this test. I recommend in my book before doing this type of testing that you measure you test light current draw first. Oh, and keep that power probe away from this type of test.
the test light is the load. most test lights will draw less current than the solenoid itself would draw. you should always measure the current draw of your test light before doing this kind of testing. most of the incandescent bulb test lights draw about 200ma.
Timeless and amazing Paul!
Thank you my friend
I use a 194 bulb with a couple of the proper terminals to plug into the vent solenoid connector. Use the scanner to operate the vent solenoid and prove out everything at once. Even pin drag. I used to use an 1157 bulb, but somewhere around my2006, the pcm stopped driving that much current for these circuits.
having the voltmeter hooked up wouldn't change anything other than potentially the male/female pin contact at the ECM. You may have a loose pin that was temporarily tightened up with your t-pin or whatever you where using.
This may have allowed the system to finish its other checks. So it sounds like you also have a purge flow issue. Most common cause for this code is reversed vacuum hoses on the purge solenoid under the hood or a sticking purge solenoid
How about watching that control wire voltage at the PCM during a test drive. Rig up your voltmeter to that wire and put the meter inside your truck. See if it ever changes. IT should only change when it is commanded on by the PCM.
awesome dude. Thanks for the feedback!
Very good advice , thank you .
@foxholewilly When I say "doesn't support current flow" I mean no measurable amount with our conventional meters and scopes. There is some and it is in the micro amp range. I don't have anything that reads micro amps, nor do I have the need to.
Thanks for the reply Paul. I took the vent solenoid off the car to bench test it. I'm holding it, and I gotta be honest, I don't it's the type that you can blow into to test. If ya type chevy cobalt 08 vent solenoid in google it'll show up as one of the first pics. It's cylindrical. Also, I should add the solenoid goes directly in the canister. There is no vent line that goes directly to the solenoid (from what I can tell).
@foxholewilly Oh ok that was very observant of you! In my experience with both ends of a circuit open yes you will see this "ghost voltage" as you call it. (From what I found if you zoom in on it and measure its frequency it is 60hz which no coincidence is the same frequency our residential lighting systems run.) So I would call it "noise". Anyway to answer why it was not there. First I do not know the PCM board as well as I would like to but I would say there are some......
I'm sorry man, I don't think I can help any further over the internet. Too bad you were not closer to Pittsburgh PA, I would be more than happy to take care of you for free at the school.
dude ive been trying to fugure this out since last year when i bought the car everything ealse i did failed until i ran in the the video GM EGR VALVE TESTING (P1404 CASE STUDY) 45:08 to 45:58 and holy shit it was on backwords and it was getting bad gas milllage with negitive fuel trim both st lt it perrs like a cat now i have to tell ya thank you very much i thank you saved me 100$ or more
awesome video. I feel smarter and I think you just helped me fix the problem
Thanks again for the great video.
Thks man u have open my mind even more...
@foxholewilly I'm not completely sure what you are referring to, Do you mean bias voltage? Like in Section 3 page 26 in my book? (I'm not sure if you have it, so sorry for the reference if you don't) The circuits that will typically have a bias voltage are the power side switched solenoids. I don't remember if I have ever seen that on a ground side switched one. With the transistor off there is no current path on the control wire.
the whole exparance was a gigantic pain in the ass i even took off the cat converter thanking it was part clooged no change in feed back reading even the egr tube still no chance all that work because of a backwords egr valve because somebody dint pay attation in what thay where doing when fixing it i disconnect the battery and hopefully the computer will reset itself as i heard in one of your videos and relearn the feed back value again thank you very much i cant thank you enough
@ScannerDanner It is too easy using a power probe to apply the wrong polarity to a circuit. I personal don't use one, nor do I feel the need to. Just a regular old incandescent style test light is just fine for 99.9% of driver testing that I showed in this video.
Not sure man, but you do want one that give you bi-directional controls. Look for a used snap-on on ebay.
That is a great Video, Thank you Sir.
I then checked the defective unit with a olm meter and its open, as the replacement unit is complete.Hope I didn't hurt the Driver as you stated ,When I checked for voltage at the connector with a volt meter.
Anytime my friend!
not sure off hand. I have at least two or three GMs with the linear EGR valve with issues. maybe search EGR valve?
Ok let's make sure that is the the correct white wire. unplug the vent solenoid and it should drop to zero volts
Great class video, was looking for visual info on physical location, but watched your entire video.
@Username64870 It is ok, I've done it hundreds of times and no I have never run into that. Did you make sure the key was off when you disconnected the PCM? Sorry but I don't think I can help with that one over the computer screen.
is this code immediate or do you have to drive it for awhile to show up again? I still think you have a wiring problem and you need to pull and wiggle the harness while monitoring vent solenoid control wire voltage at the PCM connector. It should stay at 12v the whole time.
Can you apply a power or a ground to a circuit with just the touch of a button with this tool? I know the older power probes do this. Also what is the voltage threshold that will light the green LED indicating a power source? There are other concerns I have with this tool too. Take a ground side switched solenoid that is not being grounded yet and check the control wire. This tool will ID the circuit as a power feed, but what it really is, is a switched ground. I suppose a DMM does the same.
I mean continuity test*.two other options which come to mind are (can you hear crazy but when you dont have the right tools you have to improvise) put a t-pin in the ecm plug and disconnect the plug and place the test light to ground battery and place it in the t-pin of the plug of the ecm and then jump the 12 volt feed of the solenoid to the control wire and check if the test light comes on. The only danger that I find this test is if the control wire is shorted to ground will blow the fuse
Hi Paul
Awesome Video.I noticed that you mentioned that if we see CIRCUIT in the definition of a EVAP code ,it is an electrical not a leak issue,but I had a 2000 Porsche Boxer with P0446 EVAP CIRCUIT problem.The German definition of circuit is SYSTEM not wiring.The canister and line from canister to purge solenoid was plugged... HA .I replaced the rubber line and cleaned the canister and no more P0446 .Isn't that funny ..CIRCUIT not SYSTEM
Thank you
This video is awesome, i have a 2007 Yukon with 5.3 and have already replaced the evap solenoid. I should have tested the signal wire from the computer back to the solenoid. i am pretty sure i have a faulty driver=( Great video though, thank you so much for sharing!
It's most likely a broken wire inside of the insulation, right at the connector. Like in this video
th-cam.com/users/edit?o=U&video_id=0OumX9covQc
I'll check it out, thank you so much!!
What's the word? I've never seen a faulty driver for a vent solenoid on a GM
I am going to work on it later today. I have power at the fuse, the connector (on both sides of the connector) but no ground at the connector or right out of the ECM (with truck in run/on).
With the hustle and bustle of summer time haven't just got the chance to actually dig into this issue (P0449). I have 12 (and some change) at the ECM, i have 0 volts at the EVAP vent solenoid. I have no way of actually operating the driver, so I can't confirm i have the correct wire at the ECM. I am assuming the control wire is the same color from front to back. Do you know which pin the EVAP VENT SOLENOID is at the ECM? if not, could you point me to where you generate your wiring diagrams from? I joined the scannerdanner website, looks great tons of info. Thank you in advance for any and all help on this
I actually did laugh out loud
At the 25-27min. using the test light is the key on or off ? I am guessing key off.
What signals computer to ground the control wire and activate the solenoid. Does the Evap purge solenoid operate the same as this vent control solenoid ? I do not have the ability to ground the control wire with a scan tool.
My vehicle is a 1996 Olds.Lss 3.8 S.Charged. I have a P1655 Evap Purge solenoid control circuit code combined with a P102 Mas or Vol Air Flow A Circuit.
Your video is the best for explaining this circuit I have seen.Thank You.
For some of the tests the key must be on for the computer to have power and for the feed circuit to get power.
For the short to ground test in the harness on the computer side, the key does not have to be on. In fact, I think I have the computer unplugged in that example right?
Your purge solenoid is tested the exact same way as this vent solenoid in this video. It is power side fed and ground side switched. It is possible the purge and MAF sensor is on the same circuit for power. See if you have power first.
Yes, BATT voltage and ground can be applied with the switch. And without pushing the switch if the probe tip touches a grounded source, the light will go green. But if it touches a voltage source it has a red LED that lights. So in a sense PPIII and DMM sorta same. So any suggestions to a good scan system that a work-from-home mechanic should look into? Local part store has a OBD1/OBD2/ABS scantool,but it does no live data or sel/relay acctivation only FF all for $500.Only 1 can find under 1K.
Great Lesson......where do u get ur wiring diagrams?
In the second test if the test light doesn't comes on its mean you have a shorted to ground control wire. And is will be easy find the short because that cable will have steady 12v from the jumper cable of the battery positive. then it is a matter of search the voltage drop in the cable to find the short. Well that what I think and again sorry for my English
Okay, so if don't have the scan tool the only way should be a test drive to see if the pcm will turn on the driver? or this will happen at idle?..
what is the voltage with just the key on engine off
Thanks brother
because electricity follows the easiest path and your t-pin is now the easiest path so it bypasses the normal resistance in the circuit. This equals a huge increase in current. (resistance goes down = current flow goes up) BE CAREFUL WITH T-PINS!!!
Good video.With my Pontiac Montana off and on my red wire only reads 4 to 5 volts when testing to ground. White wire reads 0 at all times with plug out,not pin tested while still plugged in to solenoid which might be ok? This is going to the purge solenoid,not the vent solenoid which is in a very bad location to get to unless I roll the engine frontward after disconnecting bone brackets on front.
i thank its a bad pcm but i need evidance to state other wise but the feedback voltage is 1.5 at idel i thank its supposed to be lower in the milavolt range
Hi Paul what if don't have the scanner to energizer on and off? can you do with a test light? and since is 12v circuit using the test light is safe?
Thanks brother for another great video. I have a 1997 LeSabre with a p1655 EVAP Purge Solenoid Control Circuit code. My scan tool is not bi directional and I wanted to know the best way to test this circuit. Can I use the test light to activate it ? Thanks brother
Just wondering, in your videos(unsure about in your book) Haven't seen you use a tool like a "Power Probe III". Is this cause they can be dangerous to computer curcitry or just because you have more advanced tools at your disposal?
EXCELENTE
Great video Mr scanner, how much is the book, I would like to buy it, thank you, take care yourself,cheers from Ontario ca
i own a 97 grand am gt 3100 4 door and i have a p1406 egr pantal position sensor circut dtc the connector has 5 wires going to the egr i checked the feed back wire and its at 1.5 volts at idel and about 1.7 at roughley 2000 rpms i checked all the wireing to the egr valve from connector all seemed fine i even ome checked the connectors going to the pcm from the egr connector and all seemed fine i thank i have negitive fuel trim it seems to gets bad gas millage plus when you pulse the brake
and the other option is instead of using the feed of the solenoid wire using a cable that go from battery positive to the placed t-pin in the control wire and check if the light bulb lights up. These 2 tests it can perform and verify that there is a failure in the control wire right? Sorry for my english :)
Hi Paul, I'll have to work on my neighbor's car with po110 po159 po443 po157 po160 the history of this car somebody change sensors but the codes are back again, and I think start with po443 fix it first, what do you think about it? any help to start I will appreciate.
If I don't have a scanner that has that function of energize the solenoid I would have that make an omhs test in the control wire. what I mean is to use a t-pin in solenoid plug and a t-pin in the ecm plug. Right?
Are there any insulateted t-pins where crocodile clips can be hooked up safely and what are the best wire tapping tools.Thanks in advance.
THE POWER PROBE 3 IS BASICALLY A VOLTMETER WITH A SET OF LEADS THAT YOU CAN APPLY POWER OR GROUND TO ANY CIRCUIT AT THE TOUCH OF A BUTTON.ITS VERY HANDY BUT YOU CAN DO THE SAME WITH A SET OF JUMPER WIRES IF WANTED. YOU WILL GET IN BIG TROUBLE IF YOU DONT KNOW WHERE TO APPLY THE POWER OR GROUND,THIS TOOL APPLIES FULL BATTERY VOLTAGE AND FULL GROUND.IF YOU DONT KNOW HOW TO READ A WIRING DIAGRAM AND KNOW CIRCUIT DESIGN I WOULDNT MESS WITH IT. I OWN ONE AND RARELY USE IT MAINLY I USE IT TOFINDSHORTS
paul why wouldnt we fry the pcm by applying 12v with the test light and commanding driver on. technically we are bypassing the load and giving it straight 12v right? or does the light itself provide enough resisrance?
i guess thats why im not getting ground to my purge valve on top of my v6 camry engine on 12v i was wondering because my evap and catalyst never ever goes into full drive cycle and my engine temp is above 176
paul, why would the pcm fry if the t pin was touching ground on a positive side switch?? too much current flowing through pcm?
Great video Danner! i got a question, if the solenoid shorts, that could possibly fry the driver on the pcm right? so in that case we would have to replace the solenoid and the pcm? thanks a lot!
yes, that is always a possibility.
hi ---Please help --- i have a 2001 camry v6 operating at 178-181 temp, ecm will never go into full drive cycle with the evap and both catalysts i disconect battery few times and driving over 300 miles i need to pass inspection
scanner danner why does the pink 12volt wire stay hot even if the key is off, 05 Colorado, the control wire is ok to the pcm driver ,the problem im having is the vent valve is not closing when the purge starts to do a vacuum test via pcm, causing a large vacuum leak to the intake making the longterm fuel trims to hover 16%, when I put a plastic plug over the vent valve tube they return to normal, I cant figure why the vent valve is not calling to close,, please help diarstraits eric martin lv nv thank you
I got a p0449 as my only code. 05 buick rendezvous. Is it possible some other sensor is causing the computer to close the vent solenoid on purpose-the whole time the ignition is on? Meaning sending a ground signal to the control wire to close the vent solenoid because the computer is sensing some other problem like maybe a bad fuel pressure sensor in the tank or something else strange?
ok the egr was put in backwords the pantal (the piece that moves in and out) the vacume side of it was put on the exzust side so that when the car ran it would suck the pantal open lifting up the valve off its seat and uncontrolabully let exzust gas into the enigine when not commanded the engine ran but runs a lot better now it dont shack like it used to you could see the engine shake a little the feed back voltage is 1.05 at idel instead of 1.5 volts and 0.9 volts with key to on not running
Just diagnosed this on an Escalade 6.0. 0.5 V on the ground side at the ecm connector when commanded on and 12V when off. Bad ecm driver
No, those would be normal numbers for a ground side switched circuit
Thank you for the quick reply. I immediately re evaluated the Escalade and found a wire rubbing on the driveshaft 😐 I was expecting to see a voltage drop on the ground wire between the ecm and solenoid. Thanks to you I caught the real issue before putting in an ecm that is perfectly fine!