Thank you. I am a mobile mechanic, recently had a customers car a 1997 Pontiac Bonneville with an EGR code. I used the info in this video to diagnose a faulty EGR valve. I had the 5v reference at the connector, and couldn't get the valve to click by applying a ground through the VOM.
You Sir are a legend! A proper mechanic who actually diagnoses faults not just throw parts at a computerised diagnosis. I have a problem with my Vauxhall 3.0CDTi right now and if you were in the UK I'd be bringing it to you!
The best. A proper explanation will take the student to the next level in repairs. You have given a valued service to each of f us watching. Thank you.
Glad i had this video brought to my attention. Having an issue with my 99 blazer p1404/p0405 tried 2x new OEM replacement egr valves + brought to a local chevy dealer they had to call GM directly because they couldnt figure out why it wasnt working. I check the wire harness and found the 12v red wire for my EGR valve is not getting any voltage from the pcm.
During the video I was thinking a cheap easy fix would be to jump the two 5V ref wires externally...and that's exactly what you did. Beautiful! Also for fun you could pop the cover off the computer and trace the circuit board to find the broken connection on that leg of the 5V ref.
This video has been the most helpful I've found. I just bought a truck (2005 Ram 1500 w/ hemi) and right after I left the guys house the CEL came on. I should have gone back but it's mine now. Anyway, it was P0401. I started looking into it and could tell the EGR valve had been replaced because it was so much cleaner than the components around it. I took it off anyway and bench tested with 12v and it works. I cleaned the EGR tube while I was at it. I think the valve is hot side switched (controlled by the power train control module). The 3 wires that I assume are the potentiometer show ground (low ohms to ground), 5v (tested 5v to ground), and the last measures something like 4v to ground. This is with the ignition on, engine off and valve closed. I bought a new valve thinking the signal voltage should be around .8 v but it also measured around 4v. Are any cars set up such that a higher volt reading on the pot indicates the valve is closed, and lower voltage is open (opposite of shown here)? I'm starting to think it is a control module issue, but I don't want to give up yet. I checked continuity to the pins at the module and the 12v, signal, and ground wires all show continuity.
I was going to try to pull the EGR valve and clean it, now you have convinced me to troubleshoot it first. Of course it is totally inaccessable. Thanks so much for the video. Ram 1500 4.7L
Scanner Dan GOOD Good JOB!! Using the AMP section of the multi meter as your jumper wire (as long as within the normal range of the meter < usually 10 amps > ) . I've been an electrician many many years and that was a great TIP for everyone. I wish I had a dollar for every time I went to build a jumper lead, when all I needed to do was use the internal multi meters circuitry to complete a troubleshooting scenario. Taught this old dog a new trick.
Thanks for this video ScannerDanner! I've been fighting with a rough-running Vortec for ~3 weeks, and this was EXACTLY the sort of video I needed to sort out the issue. Tripped over waaay too many "uhh... here's 12 minutes of me shooting a parts cannon at my truck" videos before finding your channel. THANKS SO MUCH. Clear video, clear audio, logical progression. Well done!
I've jumped similar ref wires several times through the years for 'poverty stricken' customers... but only after thoroughly explaining that the mod has to be at the customers sole risk. All were successful. Those welding tip cleaners are a fairly common tool truck item... but they might be tucked away in a drawer... ask you tool guy. Great videos, Thanks man!
Seriously cant thank u enough. This video was like a missing piece of this puzzle i been putting together called a 3400 engine. I honestly feel i got 10 times more knowledgable on this subject from watching this. Respect sir.
an alternative way to get a 5v ref to the egr is to use a LM7805 or a LM7905 (different current ratings) three legged voltage regulator, which is very similar to the voltage regulator in the ecu, run a lead to it from the switched 12V, these can be bolted to the case of the ecu
i use my scan tool in EGR override on digital EGRs to command it open to about 90% and then closed while keeping the engine running with my right foot on the throttle.. this has cured a LOT of 3 solenoid EGR valves and stopped the pinging.. it also improved the throttle response and fuel economy went way up as the dilution of the O2% in the incoming air charge reduces the amount of fuel needed. this really is seen in open loop acceleration.
OMG. This is awesome! I hope you are getting paid well. I've had a check engine light (CEL) issue with my 97 Isuzu Rodeo for well over 5 years. (after I wasn't sure if my AC compressor was shot so I hot wired the relay to get it to run and melted some wires but that's another story) Several codes were thrown at this time. #1 cyl misfire and p0120 TPS error code. Took it to a $150/hr repair shop and shelled out a thousand dollars for them to replace the EGR valve and TPS and supposedly "clean out the ports." Check engine light came on in less than a week. I tested the purge valve solenoid and it was bad. Replaced it and CEL went off. Then it came on a few months later with the p1406. I used my OBD scanner and iphone app to clear the code and pass inspection. That no longer works. I figured there must be a bad wire or an ECM issue but didn't know how to diagnose it because, as you pointed out, the wiring diagrams as detailed as they are, don't show the whole picture. Anyway, I'm going to use your video to diagnose and fix this problem because this is exactly the issue with my truck. I hope you read this far because you mentioned your book. How to I order it? Thanks bro!
Thank you! From my website at www.scannerdanner.com Is your Rodeo using a GM electrical system on this year? I can't remember. While you are on my site, sign up for my forum, it is free to join and we can absolutely walk you through testing this if it is different than this video.
No problem, just be careful with it, as Bushougoma said. You must know the current flow of the circuit you are jumping. Make sure it is well under the 10a rating of your ammeter. Otherwise you will blow the fuse in your ammeter.
Being comfortable working with electronics myself I'll often open up the ecm and look for the problem. If it's a cold solder joint, then it's an easy fix. If the circuit trace actually burned, then I would be concerned about over current caused by something going on in the field on the dead 5v circuit and would do some looking around. In any case I would fix the bad trace and put it back together. If the trace was burned I would have been concerned with simply replacing the computer because whatever caused the trace to burn will likely be a risk for the new computer as well.
AT LAST A FIX FOR MY CHEVY 4.3L VORTEX ENGINE, POSSIBLE FIX FOR YOURS! Hi, I have a 2000 blazer with the same problem as you and thousands of other people out there. NO one could figure out my problem. I purchased my blazer used last year with 113,000 miles on it. It ran great over the winter and this spring it started misfiring on cyl. 4 just like yours. I changed everything in the ign. system just because of the age, hoping it would solve the problem. It did not. NO big deal, plugs, plug wires, rotor, Inlet air temp. sensor, distributor cap, coil, & alternator. They needed to be replaced anyway, but what a bummer I still had a misfire on cyl. 4. To make matters worse, I would only get the code P0304 (misfire cyl. 4) only a few times in months of driving. No other codes came up. It would be worse on wet or low air pressure days. On dry days, or higher air pressure days, the problem would be almost nun-existent. After four or five miles of driving first thing in the morning, the misfire would go away and the engine would run great for the rest of the day even if I let it set for ten hours while at work. It only gave me a problem first thing in the morning. I would leave my house going up a hill for about a mile. The misfire would only show up around 2000 RPM when the engine would try to shift, then the misfire, and the trans. would jump from first to second in and out until I would let off of the gas and let it shift and then give it more gas. kind of like driving a standard even though this is a automatic transmission. I asked everyone that new anything about automobiles if they had any clue of what the problem might be. I got the same old probable cause problems that I have already tried. I new a good scanner would help a lot but I do not own one and so many other people do not own one, so I thought I would try to find the answer with good old common sense and testing. Four weeks or so I read and watched every video and training article that was related to my problem, and what I learned was amazing! I found out there are thousands of people out there with the same exact problem I was having with my engine and nothing seemed to work. Knowing that, I began to realize it was not a simple, obvious problem that was addressed often. To find this problem I knew I had to understand how all the parts worked and how to test them. I learned how to test the sensors with a meter, so I tested every sensor on the truck I could using a vac. pump, volt/ohm meter and everything tested GOOD. I tested the MAP sensor, Crank Case sensor, Throttle Positioning sensor, MAF sensor, Air Temp. sensor, Cam positioning sensor, EGR valve checking for 5 volt reference, correct signal voltage, and good ground. I noticed the problem was worse on wet days even if it did not rain and the engine was dry. I figured it must be a pressure thing because the problem was worse with wet days which equals lower air pressure. Now with that in mind, I looked for a control that worked on air pressure and on my engine it is the MAP sensor. I unplugged the MAP sensor and wow, it ran great with no problem at all. Now I have already tested the MAP sensor and everything tested great. I started looking into how the MAP sensor works with my system and found it monitors the EGR valve, and sends results to the computer to help in adjusting the timing under load at certain engine conditions. I plugged back in the MAP sensor and the problem came back. Knowing it monitors the EGR valve I decided to unplug the EGR valve and give it a go. Behold, the truck runs great with no problems. Of course it is running very rich and this is not a fix but a clue to the problem. I should mention that the 2000 GM 4.3L Vortec engine uses a lineal EGR valve. This valve has only one solenoid and uses no vacuum line connected to it. The EGR valve has a throttle positioning sensor (potentiometer) built into the EGR to tell the computer what percentage the valve is open or closed. It is a five wire plug. One wire 12VDC, one wire 12V ground both used to operate the EGR pintle movement. One wire 5VDC reference, one wire signal wire(voltage back to computer), and last is a ground wire. I removed the EGR valve again to double check it. The original test I preformed on the EGR included a good cleaning of any carbon build up, cleaning and checking the pintle and seats for any build up, a 12 volt power on and off confirming pintle smooth movement, and a ohms reading on all pins confirming ohms drop on the pintal positioning sensor. Something bothered me though, I noticed when preforming the pintal positioning sensor test. About 1/8" of an inch of the pintal being pushed in, the ohms jumped to a reading 1K ohms lower than it should be for about 1/2 a second and then return to the correct value. Every time I pushed the pintal in It would do it. kind of a hiccup of sorts, other than that, the EGR tested perfect. Pushing the pintal in, the ohms started at 4.9K closed valve and drops to .57k open valve. Valve closed= 4.9k Pushing pintal in very slowly = 4.9k-3.8k smooth fall. Continuing pintal inward from 3.8k it would drop instantly to 2.7k for 1/2 second and return to 3.4k and fall at a smooth rate as the pintal continued to be pushed in.. Now if this was on a good scan tool it would show up as a quick voltage drop. Still easy to miss. Anyway, I changed the EGR and problem solved. Truck runs like new. I know you may have changed your EGR valve, but even new parts are bad off the shelf. It would test good, you have to move the pintal in and out very very slow and watch for the ohms to change in a smooth up and down. If it jumps around at all, there is a problem with the pintal positioning sensor and the EGR needs to be replaced. I Got no codes for bad EGR The only code I got was P0304 Misfire Cyl. 4 Sorry so long, hope it can help TayloredSteam
Man, you rock! Professional, efficient, to-the-point, practical teaching. This is rare. I've got my degrees and experience in electrical/electronic engineering and I really appreciate your content. Subscribed.
Excellent video, Easy to understand and great knowledge being shared here. I like how in depth your repair is, especially with the verification of the pin being good inside the connector; a lot of technicians skip that step. Video quality and audio quality is excellent as well. Subscribing to your channel!
Thanks Paul , great way to start my Saturday morning...... EGR testing videos w/ ScannerDanner! Love the jumper wire tip, plus it’s also fused through the meter. Not that you want to start blowing meter fuses, but you know it’s a tip to get you through a situation.
you're great with those scanners!!!! I'm in automotive school and also learning a lot and man idk why people say it's a waste and that they just take your money but no where no how has anyone taught me how do diagnostics just like in your videos. a little tricky at first but I'm getting better, I don't just replace parts on my cars anymore
Awesome Cesar! And I have more stuff too when your ready. Fill out the form on my website for a 30 day coupon for SD Premium. Mention this exchange. I'll bring you right into my classroom. Thanks again!
+ScannerDanner nice thank you! once I'm done with this semester I'll sure be looking for more!!! what is a scanner that you can recommend to a student? not a 10k device
Well, I have a 93 Lesabre, so this definitely wasn't a "i wont ever see one of these" sort of deals for me! (unless something changed in those two years, but it appears the same from looking at it). (ALDL computer connector). Hoping you have another repair with this one. Thanks for posting, I also re-learned how to properly determine the ground side switch of a solenoid, unplugging the connector is a good trick.
It would be a really good idea to remove your jewellery when you are working on camera. There are a lot of young technicians who you are role modelling for. I have personally seen horendous ring finger injuries...please give this some consideration. Thank you for being a great ambassador for our trade. We need more young techs that can fix vehicles, and not just throw parts at problems.
I definitely understand what you are saying. I am careful where I put my hands. My rings are sacred to me. One is my wedding ring and the other is a purity ring I wear for my sons. I'll take my chances with my fingers. I do talk about these with my class and have mentioned it before in a video. I am just simply not willing to take them off. Probably not the smartest decision but it is a heart decision if you know what I mean. Thanks friend.
Ok I understand. I just noticed a big scuff on your left hand. .. I am sure you were being careful when that happened also. No disrespect intended. I have a nice wedding ring too... it goes right into my tool box and then right back on when the box closes. I would hate to see a talented young man like you, become Danner the nine fingered partsman...;)
Hello again Paul. You will have to forgive me for contacting you on your family time. .. and please feel free to respond at your leisure. I am a new subscriber to your free channel, and I am looking for learning materials, that address automotive scanners in a linear learning curve, progressing from basic to advanced. I have heard you mention your syllabus at times, and I am wondering if that is an eBook, or a hard copy. I am interested in obtaining a paper version, and would also appreciate your referral to any third party materials that you have found to be helpful in your personal education. Best regards.
I have an eBook and paper book available on my website. www.scannerdanner.com It is a field manual for troubleshooting electrical and engine performance problems. Thanks!
Thank you so much for posting all your knowledge you and south main helped me so much when i got error code p0406 teaching me how to test it with the tools i had and cheap ones i could buy. I replaced the egr valve to fix it still got the same code so I hooked up my DMM to the ground and signal wire and jumped the control wire with my test light got no change in voltage it stayed at around 5 volts even though it was open it turns out the position sesor on the new EGR was defective exchanged it for a new one deleted the code now it runs great thanks .
Well done!! Definitely a good point on the older GM computers going bad a lot. It seems like the red, white, blue connector PCM's like the one in this video were the worst about that. It also don't surprise me that the new PCM also is bad cause you can find buried gold easier than you can find a good red, white blue connector PCM. Good vid as always.
Very well done and informative video, gotta thank you for this one. After determining the egr valve was bad on a 06 pontiac torrent and replacing it I ran into an issue where the new one gave -100% reading. Following your tests everything checked out n turns out the updated egr on that car has the wires reversed. Flipped em and now we're back in business lol. Thanks man
amp meter switch . Great idea. I wish i would have grown up playing with electrical. It is secound nature to Dan now. There are many videos on electrical, but every once in a while i find one with a great idea... This is one of them.
Your an awesome teacher. I love how thorough you are with your procedures and explanations. What's that saying... "Give the man a fish and you feed him for that day. Teach the man how fish and you fed him for the rest of his life." (unknown) Please keep doing what your doing. You and ericthecarguy are my go to guys for car trouble. Btw I'm totally buying your book lol. XD
Not sure yet. One thing I noticed is the buffer for scan data is now limited? I used to be able to go back and look at an entire test drive with a paused screen. It seems I can't do this anymore? If so....that sucks big time.
We need to be extra careful with these. For example, I have been playing with GDI systems lately and the computer controls BOTH sides of the injector circuit. But, with GM EGR systems, they changed it to power side switching and only control the power side. The other wire is a constant ground even though it goes to the computer. To ID which wire to energize, take a test light to b+ and touch on control wires. The one that lights up is the constant ground. The other is the switched b+ side
Excellent video, this is a gold mine of useful information to someone who is being trained for this kind of diagnostic work. Thank you for the video and tips.
Why 3 wires for a potentiometer? Seems a bit overkill. Pins can't get loose over time especially the older a vehicle gets. Thanks for showing a way to test for that. Learn something new every video. When it comes to replacing an ECU you'd better be sure, double-sure, and triple-sure. ;)
Bad ground no question about it. You must check all computer grounds before condemning the computer itself. The computer provides the sensor grounds through the board
Iv been reading your book and just wanted to say thanks again for taking the time to make it. I'm learning a lot of things they never mentioned in school
Paul, when you JUMP 5V ref wire, don't we need to make sure that the other 5V from PCM is not shorted, if we don't then 5V that u are jumping will be pulled to ground with that short.
Excellent video !!!! You know your stuff... I'm in computers but you did great job on teaching Auto repair. Loved it !!! Great Job !!! Was hoping you opened up the box and found a bad solder joint .... OK
Paul to the rescue AGAIN! LOVE your videos Paul, as always very informative and interesting! I’ll be using the USCOPE you hooked me up with 😀 to see if the EVP sensor is good… I’ve got a code 34 voltage too high on my 1986 e-150 Leor
a few things beside this being a great video.. i would think that when you applied ground to the linear EGR valve with the engine running. that the engine should have completely stalled.. i would bet that if you had another tech operating the engine speed and bringing it up to around 2500 as you force the EGR open and closed thru full range that it would restore normal operation to the EGR other than the lack of 5V ref
Awesome Vid! Here in Australia we have the same looking motor (3800 V6 Buick) in Holden Commodores, common as mud, this can apply to these motors too. Super instructional, thanks ScannerDanner :)
Another well done video Paul. Thanks you. I have never opened an ECU but I find many times "electronic" problems are actually mechanical problems like bad solder joints or broken connections that may be easily repairable. Is this possible on auto ECUs or are they conformal coated and hard to work on? This problem may be one of those fixable problems.
Thanks for this Paul. Should one ever worry as to why the 5V reference went missing. I was thinking of, say, an intermittent short to ground in the EGR reference circuit that may have blown out a very thin track in the ECU and potentially could do it again with a new ECU, or if you wire in a jumper to the other pin with the 5V with the faulty ECU, could take out the 5V ref. completely rendering a non-functioning engine! Only ask as, like you, want a repair to be a permanent fix with no come-backs! Or have I missed something...? Thanks, Nick
Wiring is always a concern and your questions are valid. For intermittent wiring problems a visual inspection is about all you can do. (hate intermittents). The 5v ref circuit is pretty hardy, fix the short to ground and you'll fix the problem. I cannot think of a time when I had a shorted 5v ref circuit that it also cooked the 5v reg in the computer. They are protected very well. Thanks Nick
It will not because with the driver off there is no ground and if the driver is on there would be equal potential (12v on the tip of the test light and 12v coming from the driver)
i def aspire to b as great as a diagnostic tech as u r simply cause no 1 else wants to invest the time and money into the rite equipment to give a thoro evaluation....Thank You for the inspiration! i will def b ordering ur book soon, and def will continue to show u love on ur vids!!!!
Wow man... I know some about cars and am trying to further my knowledge, and I have found the place to do it... This is your first video I've seen, and I hear you reference sections... I'm not sure what it's to, but I will find out, and I will study, and I will master as you have. Thank you for the GREAT video, your extreme attention to detail to explaining what's going on, and for simply putting this much information for free on RU-vid. I truly hope you are doing this at the school you referenced, you get paid well, and the students love it and soak up the plethora of information you offer. Thanks again. ScannerDanner.
Thanks so much Matt. I do teach at a tech school and the sections I mention are from my engine performance book I've written. It is the main tool I use to teach my class. I have it available as an eBook or paper book from my website. www.scannerdanner.com You will not be disappointed, I promise! Keep watching the videos too. I have hundreds more.
No, because there is only one 5v regulator. IF there is a short anywhere, the entire circuit gets pulled to ground. Watch my Honda Element no start video.
Fantastic diagnosis. Was that a rebuilt PCM the car owner purchased? They seem to solve one problem and then cause a completely different problem afterwards.
How dose a reference signal fry , I assume if probing with b+ and using a test light you may send a damaging voltage to the pentameter and blow a diode transistor very easily. depending the net voltage at end of test light. by inserting in the regulated line from pcm. Yes ,no, maybe ?
set to amps if its a low currant draw you can use a test light and be alot safer a multimeter will put out 10 or 20 amps depending on what meter you have. A test light will not allow that much current thru BUT if you are working with the computer KNOW circuit design or it may put enuff currant to cook the computer
Hi Paul, couple of points, if you jump from one five volt link on the PCM to another wouldn't the PCM display a fault code on the pcm and possibly induce limp home mode as we call it in England, and maybe put the MIL light on, the other thing, if the PCM just had a drop down resistor for 5 volts, wouldn't it vary a bit with engine rpm etc, maybe it's a voltage regulator not a resistor? Fred uk.
Paul, I know that in one of your videos you show how to run the lab scope function of the Verus and the functional test portion at the same time, could you please direct me to that I video. I would really appreciate it. Thank you in advance.
I had for a while the egr valve light po405 on but I knew that I had to clean it since I do it every two years but this time I decided to change it, so I when and bought from big city a egr valve made in Mexico and replace It, deleted the code with the scanner, drove couple mile and the engine light when back on, I check with the scanner and said again po405 position sensor circuit low, I guessed that it might had to do with the fact that is not original so I go and buy a new egr valve made in China, I replace the part delete the code and drive on, this time I was sure that it will go away but no luck after few miles (4-5mil) engine light came back on, I took out the engine computer and cleaned it but its back on again, light engine. Please can you help, I tried to find online the diagram of the engine computer to find the egr valve wire to make sure that it's 5V on it but I couldn't find something.
