Maxim24

Read some more posts concerning the P0505 code, you'll find a lot of info about this common IACV problem. Most say a faulty IACV causes the ECM to go bad. However, a bad IACV does not always cause the ECM to fry. IMO, replace the IACV then try adjusting idle. If nothin brings it down to 650-750 RPM, probably a bad ECM.

monty31

iTrader: (1)

Most likely it was the failure of the IACV that fried the ECU. Search and you will find ways of diagnosing the IACV itself.

Maxim24

Anyone ever have to deal with faulty engine mounts found only on AT's? When I first started trying to troubleshoot my IACV, somebody recommended unplugging the front and rear mounts. Prior to any of the problems I have, when I would warm the engine in the morning, shortly after starting I would hear a "TACK" noise, maybe once or twice in 3 minutes. Then after I unplugged them, even with the bad IACV, I have not heard that noise. Could these mounts possibly be a cause for blown ECM's? Can I leave these unplugged without damaging engine?

khan911

I am also the new member & have the same problem
dose any one know how to reprogam the key withe the new ECU with out going to delear any help please

max-speed

no u dont have 2 ...

the omportant thing is the big number like , it comming 2 digit number

my ecu serail a56-n63 221 but the big number is 25

i found ecu with a56-s43-323 & the big number is 25 its work with my car and still now i use it .. every thing was fine ..

& i know someone who was check some ecu with defrent code & its work fine .. for example F5 its work with ECU 25 ...

AznTran517

iTrader: (1)

Wait let me get it straight... I think I need a new ecu.I have another 01 i30 i can grab the ecu from but my question is. I have to let the dealer put in the replacement ecu becuase my key won't start the car with the new ecu?

gulfer61

I disconnected my engine mounts, and replaced my IACV...but my car still idles high and won't sem to adjust when i atteempt a relearn.....so maybe my ecu is fried? Here's a twist i haven't seen in here ye though...my car has shorted 2 ignition switches! I can still turn the car on and drive, but some stuff will never turn off!! I have to take the battery ground strap off if i'm leaving the car for more than 15 minutes or else risk draining the battery! any comments?
Can someone explain to me like i'm a 6 yr old how to remove the ecu in my 2000 maxima?
cheers!

unrealii

iTrader: (8)

Go to the fsm link in my signature and download the manual for your car.

gulfer61

well i did that...but it's maybe a billion pages, and the only reference i can find to the ecm (ecu?) doesn't do anything like show pictures of where it is, what panels/clips to remove or anything like that...............
thanks though............

nakis

Just remove the side panels that bridge the center radio console to the center hump, one from the driver’s side and the other from the passenger side.

There is 4 little bolts holding the ECU to a sheet metal frame, use an 8mm wrench to remove bolts. The bulk connector to the ECU is removed with the black lever on top of the connector, push on tab to release lever and swing to other direction.

gulfer61

Mine turned out to be different, but knowing to try the passenger side helped...thanks for that!
I took out my glove box so i could get the screws out for the panel...then i heated up and cut with a knife a bit of the underlying plastic housing to see the ecu box clearly........it was held in with 2- 10mm nuts...and had another black box on top....anyone know what that is??

Anyway, i disconnected the ecu, removed it, opened it and ta-daaahh......no little burn maks at all...it looks pristine!

my engine/ignition short started after something burned...i smelled it....but apparently it wasn't the ecu....anyone care to take a guess?

i replaced the iacv but my engine still wont' idle correctly and i have this short circuit so that my ignition will not turn off completely and will therefore drain the battery in a couple of hours.

jh15

iTrader: (1)

did you solve this? I am about to start this 40 miles of bad road journey, and happened on your post, similar to my problem. I was googling and searching forever to find where engine computer was even located.
About to inspect ecu, then check stepper motor and engine mounts, and coolant leakage. Knew I shouldn't have taken this as hand me down from wife and sell my beloved 20 year old Caravan.
Edit: after 3.5 hours, found and got unit onto bench. Fearing the worst, as I could hear stuff rattling inside.
Sure enough, an exploded driver chip, a sta509 I630, the by itself. Don't know yet if it drives the H-stage transistors next to it nor which engine component it runs, the road winds on...

billygeg

Many peopl like myself are coming on here for help and direction on whats wrong with their cars..We are not dealers or professionals so why not stop with all the abbreviations because noone knows what the hell your talking about when you say ppsa ssdf rgty or whatever..C'mon! Cant even understand half these posts!

jh15

iTrader: (1)

One thing that may help you, is to post other than in a six month old post.

Abbreviations help in not wasting time typing, and getting to the problem in hand.

On the other hand, you may be discovering this forum frothing at the mouth over your car problems, and getting more frustrated when in need of finding quick information, needing to jump hurdles.

Bear with us, search a bit, and Google a lot.
I couldn't imagine typing out idle air control valve every sentence. This is not MacIntosh or Windows. Some will spoon feed you here, but most will teach the man to fish.
So, what is your problem, and can I help, being one the idle air control valve or ECU survivors?

dizee

that's right, i'm resurrecting an old thread.

this past friday, on my way to work, i get into my 2001 5 speed and start the vehicle. i instantly hear a loud pop. since i'd replaced the bose head unit a few months ago and 've been listening to the stereo loudly lately, i attribute it to a speaker. nothing seems amiss, so i leave.

once i've gone about a mile, i notice that at low engine speeds in higher gears, the throttle was cutting out a little early. i've dealt with the throttle cut issue described in TSB NTB01-018a for years (having shown the TSB to the dealer when in for unrelated issues and asking them to fix it, they never did), but never in third gear.

i realized i had a bigger problem whenever i pulled up to a stoplight and it began idling erratically.

took the vehicle home, pulled codes -- P0505. checked FSM, researched it. ended up pulling the throttle body. i pulled the IACV, tested the voltage to its harness as well as resistance across the valve motor leads. all good (battery voltage at pins 2&5 and ~22 ohms @ ~80F, respectively). inspected the valve itself - it was dry as a bone. coolant was also free-flowing through the channel.

looks fine, cleaned everything, reassmble. still having erratic idle.

pulled the ECM and i see this:

http://lh6.ggpht.com/_KN4ZjYRUpiI/S8...2/IMG_1103.JPG
http://lh5.ggpht.com/_KN4ZjYRUpiI/S8...2/IMG_1100.JPG

given the symptoms, the pop that i experienced, and this evidence, i'm pretty damn sure the ECM is toast.

i've seen prices thrown around between $90 and $200 in various maxima.org threads. this seems insanely low for such a sophisticated electronic component.

i'll see if i can't locate one in a junkyard, but MT maximas are hard to come by.

my question to the maxima.org guys is:

- where's the best place for me to get a new ECM?
- should i attempt instead to replace that single shattered chip?
- should i go ahead and replace the IACV, even though it tested fine?

dizee

dizee
Newbie - Just Registered
Join Date: Jul 2002

heh; that's funny. "just registered"

nakis

You need to replace your IACV, even though it tests out fine. DO NOT PLAY AROUND with your old IACV.

If you are hesitant in taking on replacing the chip your self, you might want to call some TV repair shops to see if they will replace the STA509A for a small fee, because a 10 pin IC chip is childs play for them.

dannodotcom

Having spent hours and hours reading on this forum about code P0505 and the IACV and ECU I think I can go ahead and start diagnosing the problem. The car (a 2000 SE Auto with Traction Control) is giving code P0505. I have the FSM and could just go that route diagnostic wise but I was thinking why not just pull the ECU and open it up and check to see if the STA509A is fried? Then I know 2 things, I need to fix/replace the ECU, and I probably need to replace the IACV. The CEL light just came on and I have not driven it even 1 mile since so am hoping that the IC is not fried yet and that I just need to replace the IACV. Does anybody have any words of wisdom on this approach?

BTW, this is a really great forum!

dizee

i'll preface this by saying that i have a 5 SPEED 2001 SE. point being that i do not have the electronic motor mounts that have been implicated in this problem elsewhere. at some point i saw mention of someone having two STA509As, so i'm really not sure what sort of strange differences might exist between the automatic and the manuals.

it's odd to me that you see the P0505 before having any sort of obvious mechanical issues. my P0505 didn't assert itself until some time after the ECM was already drooling on itself. it all started the moment i cranked the car in the morning to go to work. i heard a loud pop as it turned over and then i began to worry. the idle was crap after that and the car jerked horribly when given under little acceleration (regardless of vehicle or engine speed).

i'd read around a bit more about the autos and the electronic motor mounts. if it were a manual, i'd pull the ECM and check it. it's not difficult to pull out, but the angles are a bit weird and you'd do well to some of those adjustable angle box wrenches like i did. i lost a screw down underneath the center console somewhere while removing the unit. not that it really matters, but it irritated me

i took the advice of the guy with the gigantic reply above and went ahead and replaced the IACV. it didn't take very long. i've pulled the airbox off a million times and, by that time, i'd removed the throttle body a few times as well.

i had a tv repair shop replace the STA509A chip on my ECM. the guy was hesitant to work on my nissan tv (he got a big kick out of typing "nissan" into the "television manufacturer" field on his computer) because of the cramped quarters, but i told him i didn't have much other option. he charged me $20 and got it back to me within a few hours.

the results were mixed: i'm happy to say that the idle is back to normal and P0505 is gone, but it looks like his soldering work must have taken something else out because it's now throwing a P0443 (EVAP purge control valve). not that i care; my maxima is throwing nearly every code in the book related to emissions. one more's not going to hurt.

i reused the existing rubber gasket for the throttle body <-> intake manifold interface. the IACV came with a new one. i would have liked to have replaced the one for the intake manifold, but in all honesty i didn't have time and the existing one looked to be in great shape. the gasket on the IACV <-> throttle body interface was much worse and i'm glad the new IACV came with one because i wouldn't have felt comfortable reusing that one.

all in all, it cost me around $300. i haven't the slighest idea what the stealership would have speared me for.

this is a really great forum. this place is nothing without the community, so i feel a bit guilty for not having followed up until now. thanks everyone for the wealth of information you provide.

rottis[FIN]

My California '00 MT Max bad ecm code A56-33M Z06 9422
I hope i can fix it, only need wiring diagram for pins.I'm tired to draw diagram myself.
btw i have codes P0320 and P0302 there's no spark on 2.cylinder . I have checked sensors, wiring, coils, chanced plugs and also checked injectors. There's no vacuum leaks and the engine is good condition.

Progress

iTrader: (26)

Try $1,700. I have the same problem and will have someone do the soldering work for me, too.

http://forums.maxima.org/5th-generat...ried-iacv.html

lan6309

I hope that someone can help me. I have a 2004 Nissan Maxima. My car was skipping and jerking forward while driving. RPM going crazy. I had the check the engine light for about a month and decided to take it to my mechanic. As I was driving to my mechanic, my car shot down and refuses to start. I had it towed to my mechanic who informed me at the ECU was bad. He charged me $1700 for a new one and reprograming. I went to Ebay to get a used one. I gave the Used ECU to my mechanic. After 3days, he called me to say that I still need a new ECU. I am going to have my car towed back home because I can not afford the cost. ANY ADVICE? Please someone help. I am unemployed. PLEASE SOMEONE HELP! Can I fix this with lower cost or do it myself?

koreanthunda

i have a 2001 maxima and had the ecm sta chip repaired and replaced the iac valve and the car was fine untill i tried to do the relearn procedure for a 03 maxima , then the idle went high then low for several seconds untill i figured out I didnt need to do that since I have cables , then the idle went back to normal now I did the relearn procedures 100 times and now I have a no idle condition untill i let it run for 5 seconds or so with the gas then When its cold it falls on its face , So i went to the store and had the test run for codes and got the p0505 code again, ! WTH I am about to junk the car or question the ecm repair which might of fried the iac valve

koreanthunda

Well I finally got the relearn to stay and it works good it when I but the gas when cold it bounces back , I might try the relearn again . What I did was disconnect the battery and computer for a while the went for a 20 minute ride then started it and the idle was there and to think I was going to send it back to California to get checked out again once I opened it up the Chip was still fine . I should of bad the consul2 done by a shop but I save every penny but not aggrivation. Lol

Stru

My issue seems to be similar, but at the same time much different. CEL is on, P0505. Not gonna put all the blame on the IACV or ECU just yet, but I will say that the issue my car has is starting.


Not my video, but that is EXACTLY what it does. I did some more research about others having this issue, but with others they seem to have problems with stalling, rough idle, etc. when I don't have any of those issues. My only problem is starting the car. I have to rev the gas as I'm starting it and keep my foot on it for about 5 seconds before the engine decides to actually stay on.

Is my ECU fried? Should I replace the IACV? Is it possibly the camshaft sensor? I don't know where to start here...

Ryan Beers

150