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- เผยแพร่เมื่อ 9 พ.ค. 2019
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Bonus information in the video, regarding checking THAT ECM/ECU fuse, and if you read this, I later had a TPS failure.
2001 Pathfinder Idle Air Volume Control motor failed. Coolant helps warm this intake function.
IMPORTANT: At 1:05, the coolant statement is incorrect. The coolant does NOT come in contact with the AIC motor. The AICV can be replaced by removing the two Philip Head screws, rather than removing the whole assembly with the HEX Bolts.
The electric step motor(solenoid) fails, grounding out and the increased current burns out the Engine Control Module.
Shortly after the IAC failed, so did the Throttle Position Sensor(TPS), which is the other sensor, with two connectors. I think Code P1605 activated which can mean a Lean Fuel Mixture, as this Pathfinder has a Manual Transmission, but P1605 apparently could be an Automatic Transmission Code.
There is also a computer RE-LEARN series of steps when replacing the TPS.
I researched and did not find a comprehensive step by step video. This is my explanation, which does not contain any actual work.
EDIT: January 2023. I just re-watched this video and it abruptly terminated, but all information is contained.
WARNING: if your Pathfinder suddenly stops idling, but it will still run, immediately shut off the ignition and have the vehicle towed. It might save your ECU computer.
EDIT: The AIC can be easily replaced once the air intake system is moved out of the way. I had trouble removing the connector, as the plastic has aged and is very stiff. It might be better to remove the two Philips Head screws retaining the AIC. Careful to NOT drop or damage the gasket. If you can not depress the TAB with your fingers, perhaps one can use a form of pliers?
There are SIX pins on the AIC. Use an ohm meter to check Circuit Continuity from each of the center pins to first the left pin and then the right pin. Do the same for the top and bottom three pins.
If the gasket is not damaged, carefully reinstall it. This is an air chamber, so sealing is important.
You made a huge difference for me. Out of desperation I bought a non-op QX4 after my truck died. Did some research and zeroed in on the problems you described. Worked like a charm, and I put a set of plugs in while I had it apart. Thank you so much. I now have an excellent vehicle for a small investment and some elbow grease.
Thank you for your success story. I still have my 2001 Pathfinder, as they are well built vehicles. I hope your QX4 serves you well.
Been fighting my pathfinder for a while now. New iacv ecm repair and it wouldn't start. Watched 50 videos and none of them said you check that fuse. I know that's an easy job but I only checked fuses that looked ecm related. You just save me. New fuse and ripped around the yard. Thanks for the awesome video
One of the reasons I post the videos that I do, so I can help others save money, time and their sanity. You are very welcome Jonathan. You made my day too, thanks for the comment.
Did you have to mess with the keys after the ecu rebuild?
Exactly what’s happening with my Pathfinder! That blown fuse , burnt ECU , now I know the culprit! IAC ! Prior to this it did not idle correctly . Thanks for this video!
You are welcome. Thank you for adding a helpful comment. Good luck with your Pathfinder.
This is exactly what my problem was with my pathfinder. All 3 of those parts I had to replace
And by your post, you have successfully restored operations? Congrats. Thanks for the post.
You are an absolute lifesaver! This guide will help with an upcoming repair. Wish me luck!
What happened?
@@ya472 Car kept shutting off when idling. Would drive but shut off while stopped, lights still on and everything just the engine stopped, no overheating. I got it towed to a Nissan dealership who diagnosed it with a Idle Air Control Valve "internal failure." They want 600 for the fix and recommend lots of other things as immediate fixes. Total of $3000 for necessary fixes (a couple of them being valve cover gasket replacement for $1000+, spark plug replacement for $500)
@@Great.Username WOW spark plug replacement for $500 ! what a rip-off.... I know valve cover gasket is a bit of work, but for $1000 I would just add more oil, unless you get puddles of oil on the ground... Now that you know the problem, might be wise to shop the repairs, with another shop?
@@ya472 Yeah, I'll definitely be shopping around for the valve cover gasket replacement. I got the spark plugs a while ago just never got to it. I also just got the new IAC valve. Did you need to drain the coolant before replacing the IAC?
@@Great.Username No, the coolant passages go around the IAC. It is installed dry.
Awesome… thanks 🙏.. what you said saves my CPU.. I’m not gonna use it again until I install the new idle system
I hope you have an easy and 'inexpensive' fix. :-)
Alright man I've watched this video at least 20 times but I really really need you to explain how you relearned the idle on this car, all the shit I'm seeing online is false there is absolutely no video on how it's done and you are the only person who actually had this problem and was able to fix it so please please share!!!
First of all, do you have a 2001 Pathfinder with the 3.5 engine? Other models are similar, but not necessarily the same. Secondly, the IAC and the TPI each have a specific job, but both have to be in working order. The Re-Learn procedure will not work, if either has a fault. Thirdly, there is a list of things you have to double check, like make sure all electrical equipment is turned off and the steering wheel is centered with the front tires pointing straight ahead. I also provided a couple of links in the the comments, to videos that should assist you. ??? Let me know what problem you are experiencing. :-)
Thanks for this video! My fuse was blown after p0505, your video saved me arse. Replaced fuse, car now at least starts. I’ve ordered the new valve and ECM transistor. (1) Wondering, if I replace the transistor in the ECM (keeping original ECM), will I be required to have my keys recoded, as if put in new ECM, or will I not need the key recode? Also, my car starts now but obviously won’t idle... (2) if I replace idle control valve and do nothing to the original ECM, is any additional damage possible running it temporarily this way? Again thanks, great info and video.
My understanding, is if you replace the 'transistor' and the IAC, you will need to do all the 'relearn' steps. If the defective IAC has been removed, you shouldn't have further issue with the ECM but if you replace the IAC and not do anything with the ECM, you will probably have to find another way to get the idle and TPS (throttle position sensor) work arounds. The key thing should be ok.
thank youuu
Awesome. :-)
This exact thing happened to my infiniti qx4 last winter. I've been diagnosing and fixing it for a week now and figured out my ECM was fried in that chip last night. I found a replacement ECM down at a junkyard by my house and already replaced the wiring and IACV the other day. I'm trying to figure out what I need to do to program my keys once I put in this new ECM today
I had a mobile locksmith come and program the existing key to the new ECM. It took him about 15 minutes. You need one who is familiar with Nissan.
Check the ECM fuse, and you will have to 're-learn' the IACV and the TPS (throttle position sensor) to the new ECM.
👍👍👍
Hopefully you have had success, or up for the challenge. 🙂 Good luck.
Do you know if this would work on an Infiniti qx4?
I replaced the AIC valve and the ecm and the fuse. My keys still crank the truck but doesn’t start up.
Any ideas.
If you replaced th ECM, you now need to have your key programmed into the new ECM. Locksmiths can do it, probably you need a mobile one?
I have a question. Is the failing gasket directly behind the black motor? Or the gasket that butts up with the intake?
I was incorrect, but did not fix the video. Originally I thought coolant penetrated and caused the failure. I did not edit and repost, as I figured once people get in there, they would follow their own instinct. All the elements necessary are in the video. If you have any other questions, I will attempt my best, as I probably should rewatch the video myself.
A 2001 Nissan Pathfinder LE is not running the computer burned out? Will just replacing the ECM solve this problem or is there more that is needed to get it back u and running?
I do not quite understand. If the Pathfinder is running, then the computer can't be burned out. If the computer is burned out and it is not running, do not just replace it. Something probably caused it to fail, or burn out, like that IAVC .
Typo what I meant to say is that it's not running because the computer burned out
@@UniversalPerformanceEnthusiast What issues did you have before the computer 'burned out'?
Do you know it burned out, can you smell it?
Did someone else already look at this, or is this your assessment?
@@ya472
I had an inconsistent and erratic idle one time and I do not know if my ECM is shorted or not. I changed the entire throttle body but I still got idling issues. The throttle body intake hole (air hole coming from the IACV) was modified by partial air restrictions. Now, idle is stable but you have to give it gas at cold starts and when you put ON the Air conditioner, the idle plummets (meaning that the IACV isn't performing it's function of idle air control). So I wanna know if buying a new IACV and bypassing the coolant line will solve my problem OR could it be possible that ECU might have been affected. Car runs great once it starts by giving it gas at cold starts
I have an ‘02 and an ‘04 but haven’t had any issues like this yet, since it’s seems like such a common issue is there a point of age or mileage that anybody would recommend maybe getting preventative about it and either getting a new seal or even whole new IAVC unit?
I am not sure if '02 and up are better, but the IAC commonly fails on the 2001 3.5l and burns out the ECU. I have a couple of 03 and a 04 and a 97, and three 01's, I sold my other 01 last fall. Only on the ONE 2001, which I still have, did I have a problem. One 2001 I am using for parts, and most electrical, brakes and suspension have been removed. I have started scrapping my second 2001 to fix my original, and will also use parts off it to fix my 04. I know, lots of useless information.
Do you know what code this was ? I have a 2001 Nissan Pathfinder that’s throwing a p1165 code
Yes. Best to Google that information and TH-cam it too. Apparently it can be very serious. However a CODE does not necessarily offer the problem, but a symptom of many potential problems.
Why did you need a locksmith? Did you use the ECU from the donor vehicle?
Yes, new ECU needs to be updated for the existing key/security. Sorry if that wasn't clear.
I have an Infiniti QX4 with code P0340. After replacing the camshaft position sensor on the passenger side, the car still only starts when cold. Is it possible that a coolant leak or IAC valve is the actual culprit?
Read and research this more, as I can't answer directly. Because you get a code, the answer does not always point directly at the problem. Perhaps you could even have a timing chain issue, or grime, or a clearance problem? www.carparts.com/blog/code-p0340-camshaft-position-sensor-a-circuit-malfunction/
The IAC and TCS are known to cause problems on the Pathfinder and QX4. Both will cause ECU/ECM to short out and blow the 10amp fuse causing a no start.
@ya472 In order to prevent this from happening is it the IACV itself you need to replace or the gasket used to attach the IACV to the throttle-body?
Thank you. You caught an error in my dialogue. I was thinking of changing it, but keep forgetting. This gasket does not keep the coolant separated from the IACV. I believe it is only an air seal? If the gasket is in good shape, reuse it. While I was doing the video, it is what I believed, and subsequently found out different. At this moment however, most of my memory of the process is very distant, though I do have to do it again. I took my Pathy to a local mechanic for to change and troubleshoot the TPS, and somehow they screwed up the IAC and lost parts... that was 2 years ago. If you can refresh my memory with your success, please feel free to add another comment.
The failure is inside the IAC solenoid. You can check the condition of the IAC circuits with an ohm meter. At least that was the failure on mine.
@@ya472 yeah it’s somewhat difficult to get a straight answer as people on forums say both it’s the seal inside or it’s the gasket that the IACV unit uses to mate to the Throttle-body.
Would replacing the entire unit and gasket prevent the issue from happening?
@@on1ytheb3st The issue is just an electrical failure, nothing to do with anything else, from what I remember. Perhaps now that I put on my work clothes to check my attic, I will do the same tomorrow and check & Change my IAC again. It isn't complicated. If I recall, as in the video, I did not drain the antifreeze, so that isn't the issue. I will do mine tomorrow, if it doesn't pour rain.
@@on1ytheb3stToday, I salvaged an AIC from another 2001 Pathfinder I have. The gasket between the AIC and aluminum throttle body is air control, so if the gasket is ok, you can reuse it. I updated text instructions below my video, something might be helpful?
Just picked up a Pathfinder where s previous owner went through that headache. They replaced the computer and the IAC, but now it dies after cranking over. You have to feather the throttle for a few seconds and then it'll idle. Any of this sound familiar? I've cleaned the tb and tried a different MAF.
Perhaps you could repeat the 'Re-Learn' procedure and also check the Throttle Position Sensor, as well as the wire connectors and connections ?
They may have replaced the IAC and the Computer, but it doesn't mean either the IAC or computer is doing its job. Best to start with a full diagnostic?
@@ya472 Thanks for replying.. finally getting around to focusing on this headache. I'll be adjusting the TPS tomorrow. It keeps a smooth idle, but when in drive its a bit low around 650 instead of the 750.
@@LShocker94 I have been procrastinating on my IAC issue, even have vehicle parked to work on it today. However I got lazy when temperatures did not go above 38* F today. LoL
hey guys i have a 2001 pathfinder 3.5L and it has a crazxy high idle problem it revs soo high when i put it into gear i can drive the speed limit without my foot on the gas. ive changed the maf sensor, and the throttle pos. sensor nothings changed what else can i do or replace to fix this problem?
If you watched the video, the first thing you check is the AIC, Air Idle Control. It never pays to just replace parts, but search out videos or posts that explain how to check these parts for failure, BEFORE you buy parts. Good chance too, on the 2001, if the AIC is gone, so is your ECM computer. But, go one step at a time.
Would just bypassing the coolant line going to the iacv be the easiest way to prevent this problem?
If you say so. I believe the easiest solution, is to fix the problem. :-)
After considering your question, I remember mentioning that I thought a coolant leak caused the failure. This was NOT the case, so bypassing would not be a solution. Sorry for being misleading.
Hi, Very good video. Having the same issue, can you let us where to locate the ECM is passenger side or driver side
If I recall correctly, it is above the gas pedal.
@@ya472Exactly where it was, some told me that Iit was under the glove compartment. Thank you
would this work on the QG15 de cable type? RPM on 1200 not dropping
I do not know. :-( I believe the cable type is for the 3.3 engine? I do not know the procedure except for the 2001 3.5 (Canada)
@@ya472 it's a 1.5L 4 cylinder motor I changed TB still idles high going to try it.
so whats the part # for the chip in the ecm? i have new iac on way with the p0505 code. hoping it hasnt done this to the chip though.
Off-hand, I do not know the chip, but it can be researched. You would have to be good with electronics to install the chip, as soldering can be a touchy thing. When my chip went, there was an acrid burning smell... hopefully you avoided that..,, but mine was cooked.
@@ya472 ok I'm just being prepared. I have not had a weird electrical smell at all. Checked my plug and a little coolant was there. Only had to drive about 15 miles like that home. I will find out in a day or so.
@@anthonyazais3541 How did you fix the p0505 code? I have the same problem on a 2001 Xterra.
@@jmclick.6349 I ended up replacing the ecm
STA509a chip $6.99 ON eBAY Dec. 29th 2020 - Not too bad to repair the Electronic Control Module with a soldering iron, solder for electronics, sharp small wire cutter, and solder sucker. I'd wiggle the chip until you get enough space to cut the leads. Then I'd remove the solder on the top and bottom of the board and make sure all of the old solder and leads are removed. Then install chip and solder.
What a pain in the ass im pulling out my hair I blew 2 computers have spark gas have checked everything can think of and no go have to much cash in it now this was a payback for WWII
So you installed two computers? That is incredibly expensive for me.... because of the IAC? I had to have my keys reprogrammed and had to do three relearn for AIC and TPS? I am now forgetting... and glad. LOL cept, I have another issue, but first I am checking for vacuum leaks..... it won't idle again.... silly me, I let a mechanic touch it.
I checked my fuse, it is not blown. Could the chip still be bad?
I have p0505. I bought my 01 pathfinder from a guy with a sporadic idle issue. Most of the time,, when cold it idles smooth but high. When warm the idle usually bounces in neutral or park 1500 to 2000 in gear it will idle smooth but high. When accelerating sometimes it will be jumpy when you hit that 1500-2000 band. I was told the idle control valve was replaced but didn't fix it and then the car was sold to me. I can't get the relearn procedure to complete with the flashing check engine light.
I recommend if possible, to have a 'competent' mechanic with a professional code reader to diagnose that issue. There are so many possibilities. Vacuum leak, MAF, the replacement IAC could be faulty, the ECM could have been damaged, the TPS, a cam sensor or just a bad electrical connector or the Re-learn was done incorrectly. I am no master mechanic, so I spent a lot of time researching how to diagnose for each possible failure. Even bad spark plugs, an ignition coil or bad fuel injector could cause those problems, and could trigger the P0505 code. I would probably focus on diagnosing a faulty IAC first, and the TPS.
@@ya472 thank you for the advice!
@@ya472 so I tried unplugging the iac, and it still idled the same. Wouldn't that point right to a vacuum leak? I don't know how the iac could cause it if it wasn't powered unless somehow the valve was just slapping back and forth and sometimes getting stuck high and sometimes stuck low. I'm waiting on smoke machine this weekend hopefully I find something
@@WCGwkf I do not know, but seems to me, if you unplugged the IAC and nothing changed, then that should be your problem???? They are easy to check with an ohm meter... I can't remember for sure how...... but there is TH-cam video I think, maybe check for Maxima, as they use a similar engine. Quite often I find answers under Maxima when I can't fine a Pathfinder one.
@@WCGwkf IAC is Idle Air Control
So if the car starts after replacing the Fuse. Does that mean the ECM is fine. But the cars RPM fluctuates up and down. I hope I don’t need a new ECM, what’s the symptom for a blown ECM.
In your specific case, I do not know. However, because my ECM shorted out, it blew the fuse. When my ECM blew because of the IAC failure, there was a burning smell. If you just replace the fuse and it doesn't blow, it COULD mean that ECM component no longer is shorted out, but then it probably isn't working. RPM fluctuation can be caused by many things, and one should do a systematic troubleshoot.
Also, in my specific instance, my first symptom of IAC failure, the engine would not idle. I continued to use the vehicle because I was not close to home, and was unaware of the common consequence in the 2001 3.5 engine. About 20 minutes of driving is when the ECM blew and the engine would not run. It was accompanied by a burning smell and once the fuse blew the ECM was powerless. I could have just replaced the fuse, had I known it blew and see what happens, but it was the LAST issue I discovered. Maybe just replacing the fuse could have allowed me to continue driving, but I do not know. Again, you should do a systematic troubleshoot.
Generic check of the IAC valve is in this video th-cam.com/video/BYuRKzsqp-g/w-d-xo.html
Also check out this video on the Nissan RE_LEARN procedures: th-cam.com/video/B65UAHHVN3o/w-d-xo.html
Thanks for the info. I replaced the Idle control Valve, the Gasket, and the ECCM Fuse I checked my ECM and it looks like the chip is burnt. But even with the burnt looking chip the car is starting and idles fluctuating so I got a used ECM out of a Junkyard and hopefully if I can get it programmed somehow maybe by a locksmith that might solve the issue, other than that I’m thinking the Throttle position sensor could be possible issue for fluctuations? Thanks again for the info and the video.
What is the third procedure?
I was intentionally vague because anyone playing with these problems, need to hunt for more information. I found other TH-cam videos and I researched with Google and checked out Forum threads until I found all the information I needed to get my 2001 Pathfinder running. I hope you also read the additional information I posted under the video. What I almost did not find was information about that blown fuse, so that is the main reason for this video. I have an additional problem now with this Pathfinder, concerning it not idling, because I had a 'mechanic' troubleshoot and 'fix' a code, which required the TPS replacement, but he f'd it up somehow last November and I haven't taken the time to research it further. One of my other Pathfinders suddenly had a 'no start' issue, so I have to troubleshoot that as well, so I will probably do a follow up video in a month or two. (April or May should be warmer)
I just bought a 02 pathfinder 2wd SE, the vehicle starts, but instantly dies… but if i give it throttle for 5 secs and then let off the throttle it idles perfectly, can drive anywhere anytime with no problems except when i first start it i have to give it throttle. I hope its just a bad fuel filter or maybe the crankshaft position sensor
Also, my rpm meter seems sticky and not so smooth.. is this normal or does that indicate a CPS going bad or just a sticky meter?
First of all, what engine, the 3.5 gas? There are many places of potential failure, and I would not just guess and start replacing parts. First thing, I would have the codes read by a shop, as they can often pinpoint a failure. I would wonder however if you have a MAF, TPS or an IAC issue. But it could also be an air leak affecting the MAF, or a vacuum leak, even a bad Injector, spark plug, ignition coil or spark plug boot. How many miles on the truck? A sticky (?) gauge could be a the gauge itself, the sensor (sender) or an electrical connection. There are just so many possibilities.
@@ya472 its an 2002 Pathfinder 3.5L v6, 162948 miles, codes are (P0906- Idle Air Control RPM low, P0920- Cat below efficiency BI) just tried the iacv relearn process but the part where you have to start the engine and let it sit for 20sec without touching throttle is impossible
@@SupraKing12365 I had an answer almost typed out and hit a key that deleted the whole thing, so will try again... grrrrrr I believe when attempting to use the shift key, I also hit Ctrl ? It happens far too often.
@@SupraKing12365 Search TH-cam for a video how to Check your AIC with an Ohmmeter. I don't have it handy. With the 2001, it is possible too, that a shorted AIC with damage the ECM. You basically unplug the AIC and check continuity for four circuits... using the six contacts.
Where is fuse located got the same code
I show it at the end of the video. If the fuse is blown, you need a new ECM, just replacing the fuse won't help.
I changed my IAC Valve and now my car idles sporadically don’t know why
Did you do the relearn program? There also may be other issues, like a bad fuel filter, pump, or the Throttle Position Sensor?
I would check for a vacuum leak first. Hoses crack and often mice or rats will chew the underside of tubing.
Also, the Mass Airflow Sensor might be failing, or there is a leak in the intake system, allowing air to bypass the MAF?
@@ya472 so it turns out it might be my Ecm the new valve wouldn’t open and made my throttle whistle which was the leaking sound I was looking for so I put the old one back on and it’s not surging or whistling
@@Kameron.Kennedy What year is your engine, and is it a 3.5L? It is common in the 2001 3.5 for the IAC Valve to burn out an electronic item in the ECM. What I just did, I manually opened the throttle to idle rather than put in another ECM. The engine starts fine, but at the current setting, it will stall out when doing a cold start, but once it warms a bit, it idles fine.
just disconnect it?? power
You could, but it will cause issues. First, you would need to mechanically set an idle stop, and secondly, the engine could 'diesel' when shut off. I am not sure what other computer related issues would occur, fuel monitoring?
Also check out this video on the RE-LEARN procedure th-cam.com/video/B65UAHHVN3o/w-d-xo.html
Well done. That fuse...That fuse. I was about ready to take the car to the junk yard. Thank you for the video
Thank you.. Makes posting videos worthwhile.
I have a 2000 nission
Depending on which country you are in, the 2000 Pathfinder came with various engines, including the 3.3 v6 and a diesel. Does it have an automatic or manual transmission, air conditioning, etc.. a catalytic converter?
It shudders losses rpms and then dies
There could be 100 reasons from a fouled fuel filter, to a failing fuel pump, to a collapsed hose, a vacuum leak, a bad sensor, gasket, coils, spark plugs, wires, etc. Do you have a 'Check Engine' light? It is probably far cheaper to have a 'professional' diagnose your problem, than to start replacing the wrong parts.
Generic check the IAC valve in this video th-cam.com/video/BYuRKzsqp-g/w-d-xo.html
P0505, help.😄
Let me know what you find, maybe I can.