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*Updated: 02/06/2022 5:26PM PST

01 LE cranks but won't start! Buzzing noise coming from engine when ignition ON.


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Hello!

My 01 LE pathfinder will turnover but will not start and there is a buzzing noise coming from the passenger side when the ignition is in the ON position (Buzzing noise STOPS when gas pedal is floored). I have searched through forums for hours and cannot seem to find anyone who has managed to resolve this issue.

 

What happened leading up:

4 months ago I was on a three hour drive and about half way the car shut off on the highway. I got a P0100 so unplugged the MAF sensor and plugged it back in (I had replaced it about a year earlier; thought maybe it had gone bad again) and the car started up and drove fine for the rest of the way. Two days later the same thing happed again and then the problem went away for a couple months. A couple weeks ago my car died at a red light and this time my MAF trick didn't seem to work, I got a P0100 and a P0505 this time (IAC has recently been changed). The car would start but not stay on, luckily I was close to home and I made by feathering the gas to keep it running.  

 

How I've tried to fix it:

Downloaded the ECS repair manual, and turns out the MAF, IAC, and one of the crankshaft sensors were not getting proper voltage. They all traced back to the ECM relay so I changed that today and the engine still wouldn't start. Then I found that 7.5A fuse for the one of the engine coils was blown and after replacing it all of the the error codes went away (P0100, P0505, and P0335) and THE BUZZING STOPPED! The sensor harnesses were getting proper voltage and after doing the Idle relearn process I got the car to stay on. I had taken off the harness to the ECU connector during the diagnosis process and needed to put it back on. I turned the car off, disconnected the ECU, put the harness back on the connecter, connected the ECU, put my dash back together and went to turn the car on to go get gas but THE BUZZING RETURNED! ? Car is back to turning over but not starting, sensor harness are back to their inadequate voltages, and the buzzing persists while the ignition is on except for when the gas pedal is pushed to the floor. I've checked fuses and other relays but can't find the issue here. This car is my first car and I love it but its driving me crazy (no pun intended).

 

Any suggestions?

 

Edits:

- I should also add that the security light comes and and stays solid red 3 seconds after I turn the ignition on (this occurs with both of my programmed keys). I have 2 other unprogrammed keys that turn the security light solid red immediately after turning the ignition on. Not sure if this is an indication of the Anti-theft mode or not.

 

BUZZING IS COMING FROM TRANSMISSION

Edited by chris53378
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I'd check all the grounds those sensors are attached to, and I'd verify the fuel pump is working during the prime and start process.

I'd look for cuts and frays on wires as mu as possible.

And although the car is turning over I'd probably still check battery terminal for tightness and body ground for corrosion. Those kinda things can have really weird symptoms.

I used to get a buzz for a second after turning off the car, and turning it on if I didn't go to start immediately. I figured it was the iac resetting, but never really investigated because wasn't a problem.

Sent from my SM-N950U using Tapatalk

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When you changed you iac, did you check inside your ecm if the mosfet was cracked or blackened ?  I would start with this..

 

Here's a video showing what a blown one looks like and how to repair..

 

you can also buy this part to replace https://www.amazon.ca/Lysee-STA509A-STA509-SIP-10-demeanor/dp/B07KT3F862/ref=sr_1_1?keywords=STA509A&qid=1563485910&s=electronics&sr=1-1-catcorr   (Presently unavailable but at least you get the part number)

 

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@fleurys

 

I did open the ECU when I changed the IAC because I had heard the horror stories of people burning out that module and paying all that money for a new ECU. Nothing looked out of the ordinary, no cracks, no burns, and the car ran fine for quite awhile after changing it. Thank you for the response!

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17 hours ago, colinnwn said:

I'd check all the grounds those sensors are attached to, and I'd verify the fuel pump is working during the prime and start process.

And although the car is turning over I'd probably still check battery terminal for tightness and body ground for corrosion. Those kinda things can have really weird symptoms.

I used to get a buzz for a second after turning off the car, and turning it on if I didn't go to start immediately. I figured it was the iac resetting, but never really investigated because wasn't a problem.


 

@colinnwn

 

Thanks for your suggestions! There is continuity between the engine ground these sensors are connected to and the sensors themselves and the battery connection is fine. Do you remember where the buzzing noise was coming from? For me it appears to be coming from the the passenger side, halfway down the engine bay, back toward the firewall which is no where near the IAC.

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The only thing I can think would be buzzing near the firewall on the passenger side is the abs module... you can always try to simply disconnect it and see if the buzzing goes away and if the problem gets better or not... At that point it makes no immediate sense, but at least you could advance and/or eliminate things...  after disconnecting, recheck the fuses and give it a go.. also I have seen relays that clicks but do not work properly (opening the gates)... so I would also try swapping the fuel pump relay with another one just in case..

 

basically it's either no fuel, no sparks or no air... air is usually not the case as it would probably start and jerk a bit but still it would start....

 

You need to make sure you have spark when your crank...do you have a spark tester ? if not go buy one....... For the fuel, you can also spray ether or propane or even brake cleaner in the throttle body while cranking... if it wants to start, you know the issue is with fuel...

 

let us know..the more we know the more we'll help !

Cheers.

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Well that general location is the starter motor right? I wonder if you have a loose connection or bad solenoid?

Mine sounded like top of engine driver side.

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11 hours ago, fleurys said:

 

basically it's either no fuel, no sparks or no air... air is usually not the case as it would probably start and jerk a bit but still it would start....

 

You need to make sure you have spark when your crank...do you have a spark tester ? if not go buy one....... For the fuel, you can also spray ether or propane or even brake cleaner in the throttle body while cranking... if it wants to start, you know the issue is with fuel...

 

 

Unplugged the ABS and rechecked all the fuses and the problems persisted. Swapped the fuel pump relay and nothing happened, I don't believe its a fuel pump issue because when I did get it to run the other day (before doing the Idle re learn process) it was flooded.

 

Going to buy a spark tester today so I'll get back to y'all with what I find.

 

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11 hours ago, colinnwn said:

Well that general location is the starter motor right? I wonder if you have a loose connection or bad solenoid?
 

I had to replace the starter 3 years back but the buzz is coming from above the location of the starter, I'm gunna try to see if i can pinpoint its location but no promises.

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Ok so I was wrong about the source of the buzz... it's coming from the transmission, sounds like it could be a faulty solenoid but now I am wondering if this would have anything to do with the park neutral relay being faulty (I did not get a code for it but I've heard they go bad after awhile and I don't know if it has ever been replaced).

 

There is no spark either! Could this have anything to do with park neutral relay or the anti theft mode? both of my keys cause the security light to turn solid red once the ignition has been on for 3 seconds but I don't know if it has always been like that because normally I would just start the car right away (not wait three seconds to see if the security light turned on). An unprogrammed key turns the security light red immediately after the ignition is turned on so im wondering if that 3 second difference is significant.

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The good news is that you're getting near... after reading a bit and doing some test with my own 01, here's what I think...

 

You're not getting sparks because I think the ecm is not sending spark signal because there is an issue with the NVIS (Nissan Vehicle Immobilizer System)....  Doing a test with my 01, when putting the key to the ON position, the security light goes OUT and DOES NOT come back until I either start the truck (which is stays off) or that I remove the key (which is starts blinking every 2.6 sec)....

 

For helping you in your diagnostics, I have include a link for the 2001 fsm.. I have put all the multiple parts in one so it is easier to search for a word..  get it here : https://www.dropbox.com/s/3yfr1qcihir7aso/nissan-pathfinder-2001-full-fsm.pdf?dl=0

 

Now, I did not find any way to diagnose the NVIS without the consult-II device (nissan oem)... So depending on the results of the diagnostic of this system, you would know if it is related to the NVIS itself or a lack of communication with the ECM...  I guess you could confirm with the wiring diagram that the nvis is talking or not with the ecm..

 

The pages that are in interest for you starts at EL-352.  and also you can do a few electric tests for it starting at EL-361... One of the symptoms of it being bad is a : @No start@...

 

I will try to see if I can find something on testing the nvis without having the consult-ii... maybe someone (like a nissan mechanic) can chime in on this...

 

hang in there...you'll get your baby back on the road soon... ?

 

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I don't know if this is in any way relevant, but the transmission in my '93 buzzes when the battery is low. I have no idea why. I remember the buzz starting/stopping with throttle position when the battery voltage was just on the edge of making noise. I'm not familiar with the R50 but I'd verify battery voltage, then check voltage at the computer. Maybe you've got some green crusties in a fuse link or something reducing the voltage to the computer?

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Well after Testing the IMMU and seeing that it has power and is communicating with the ECU it appears I may have tripped the NATS so I'm getting the car towed to the dealership this week because I don't have the CONSULT-II to diagnose the specific issue. Hoping I don't have pay an absurd amount of money to get this fixed. I'll be back with a diagnosis after we've resolved the issue. I greatly appreciate everyones input, definitely helped narrow things down!

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I am pretty sure most of the better scan tools will work. I doubt there are very many Consult II's left that work in the shops. When I was at the dealership the one we had was glitchy and temperamental. It finally completely died about 6 months before I left. I found that my old Snap On Verus pro(I got it in 09 I think) did pretty much everything the yellow brick did, but faster and more. 

From what the security light is doing and the symptoms, it does sound like the NATS is your problem. From what I saw where I worked, I would suspect the antenna is failing or died. It is the ring around the ignition lock that reads the RFID in the key. Anytime that security light is on solid, the engine is not going to start. Enough attempts in a row with the system not accepting the key will lock the PCM and requires a reset with Consult or equivalent scan tool to unlock it again. At least that is what I found with the ones I worked on that were towed in because the lost key that was found again but was no longer programed was used. It happened a lot for some reason.

 

The buzzing from the trans could be a relay, but if it is inside the trans, it is likely a solenoid. It could be a problem with restricted power as suggested, or it could be failing. Hard to say without knowing more. 

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  • 1 month later...

Alright so the dealership had a tough time with this one as well but I got my car back a couple weeks ago so here is a brief summary of why they think this happened and what brought the pathfinder back to life:

 

- Installing aftermarket sensors (MAF and IAC) led to some sort of shorting out in the ECU after some time

- I bought a used ECU from a totaled pathfinder for $140 (as per the head mechanics recommendation) and payed about $500 for a stock MAF and IAC valve

- They programmed the 'new' ECU to my vehicle and now it runs great!

Total Cost: roughly $1000

 

A day after getting the car back I received both a p0420 and p0430 and seeing as I don't have the money to get new O2 sensors or catalytic converters I am going to buy some defoulers and see if I can get rid of these codes

 

Once again thank you to everyone who chimed in on this post! although I wasn't able to figure it out on my own y'all helped me eliminate a lot of potential causes.

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It won't cost you anything and probably not the problem, but check the engine harness grounds where they are attached to the intake manifold. Won't hurt to check the other grounds, but the engine harness grounds at the intake manifold are where the O2 sensors are grounded and many odd gremlins have been caused by poor grounding. 

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Well the non-foulers got rid of the codes: p0420/430 but now I am getting a p0021 which has something to do with the camshaft and VVT sensor. Every time I fix something on this car another thing pops up ?. Any suggestions? I know it can cause damage if it's not tended to in a timely manner.

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That one is tricky. If the oil is full and clean, it is likely to be one of a few things. It could be a failing oil control solenoid for the camshaft phaser. It could be a failing phaser(least common). Or an internal oil leak in the rear timing cover. That is the most common I have seen. There are oil passages for the cam timing phasers in the cover that have plates covering grooves. Those plates are held with screws and it is common for the gaskets to fail and allow oil to leak out reducing pressure to the phasers. Those gaskets are not available to anyone but the builder of the timing cover. You can either replace the cover, or make a replacement gasket if they are leaking. 

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