i got the powerprobe 3. bought off ebay for like $100. it gives u audible different sound for power or ground, also the actual voltage as opposed to a test light. it also has 2 very bright LEDs pointing at work area in case u r under dash. Also you can give ground or power to a circuit if u suspect it is needed for testing purposes and has a built in breaker.

 

After reading and viewing the pictures I went out and checked my motor mounts. It looks like the 2002 GLE only has one electrical mount in the front and it looks almost new to me. I'm stopping by the dealership in the morning to confirm this.

I might decide to unplug the front mount just to be safe anyway; the car has 202K miles on it and I can't afford to be replacing the ECU. I can easily put up with a little engine vibration when idling since 99% of the time is spent at freeway speeds.

 

2001 SE automatic meridian edition...

i've been following this thread closely and attempted repair today- now it starts right up, but then idles at/bounces between 1500-2000 rpm and the new STA509A gets *super* hot, even after doing the throttle idle position and idle volume relearn procedures. i also did the adjustment to the thermal valve (closed it), but that made no difference. disconnected the motor mounts just to be safe

questions: after installation, are STA509A pins 1 and 10 supposed to have continuity? (they do, in my situation). what else to attempt- searching for vacuum leaks? troubleshoot MAF? any other suggestions? thanks for any and all responses!

 

Yes. Pin 1 and 10 are the source which should have continuity

You can do a web search on STA509A Datasheet for the complete specs of the chip.

I replaced the TPS with no luck.

I went back into the ECU, and found 3 open circuits; I guess they are the monitor/ feedback circuits. I just repaired and put the ECU back in the car, I just tested for 15 minutes, but so far it did not throw the P0505 code. I will do more tests tomorrow to be sure.
I have enclosed another picture of the pin outs for the monitor/feedback circuits.

 

Make sure your Throttle plate is fully closed, go to EC 111 of the manual and adjust the TPS. If the TPS is not adjust correctly you can damage all the parts you replaced all over again.

Get yourself an inexpensive Digital Logic Probe, Radio Shack or EBay has the Micronta, which was a big help. You will be able to test all six wires going to the IACV while the car is running and you will see if the wires are shorted (low and high signal on probe) or opened.

Pins 2 and 5 should be at battery voltage or high on the probe.
Pins 1, 3, 4 and 6 should be low and it will be switching on and off depending on how the ECU will be adjusting the idle speed and you should also see the pulse pulsating on the probe

 

After two days of driving, the P0505 code has disappeared.

Only thing now, I have to wait for the car to get into the 02 sensor ready mode, and hope it does not throw out the P0420 code and then the car should be ready for NJ`s state inspection.

Thank you everyone for the posted information, it was a big help.

 

any updates? pass inspection? i'm due for a smog check (california), which is why i'm trying to get this figured out. just got a logic probe from ebay- going to give that a shot today.

question: in your post on page one (the one with the pinouts for the transistor next to the MOSFET- pins 2, 4, 6, 8) should those circuits have continuity with the ECU out of the car? mine doesn't seem to, so does that mean the transistor is bad? the 509A chip gets hot, so that leads me to believe it's getting current from somewhere, and that the transistor is OK.... but what do i know

also- is there a case ground for the ECU? if so, i should make a jumper... i've just been plugging in the large connector with the ecu sitting on the pass. side floor

thanks again

 

Yes, it passed.

Car acts up once in a while in humid weather now and it throws the P0420 code all the time and it threw the P0100 once, it needs a new MAF sensor.

The pin outs in the pictures are to test the circuits of the board for continuity only when the ECM is out of the car.

I used the logic probe, when the vehicle was running and I had the IACV connecter off, it helped big time because I had both low and high LEDs on one circuit and the tach needle was bouncing all over the place. One of the circuits got fried and curled up and off the board and shorted onto a resistor.

If you have the new STA509A solder in, solder a sewing needle to your OHM meter probe so you can test those small points, and then test for continuity to the points in the pictures and then test to make sure they do not have continuity (shorted) to their neighboring pins.

 

I just reread your post again.

You must make sure STA509a chip pins 2, 4, 6 and 8 has continuity with that transistor pictured, when the ECM is out of the vehicle. If not the circuit board is damaged, you will need to repair those circuits and you will not be able to solder wires on to that transistor. I just had to repair one of those circuits to the transistor, by scraping the green insulation off the circuit board until the copper was exposed and then I soldered a small strand of wire as thick as a hair onto the board and then to the pin of the STA509a chip.

I guess you can test right at the ECM, you would just need a real steady hand, and just use an external power source and ground (go directly to the battery) for the logic probe, the manual states do not use a ECM ground, because damage can occur.

 

Picture of the circuit board with STA509A removed

 

hey guys, i just got linked to this thread by another member and it looks like its where i belong, its a bit long so ill have to read it all tomorrow when i get more time on my pc but i wanted to share a picture of my burnt ecu too, it looks like the same chip fried up in a couple other pictures here, i've already bought a new ecu and installed some fuses on my iacv wiring in the engine compartment but they keep popping (5amp), and my engine cranks but it wont start, will it not start because the iacv keeps going out? or will it not start because i have a new ecu and im using my original keys (havent re-programmed them, do i really have to?) also can anyone tell me exactly what chip burnt up in this bad cellphone pic (sorry) what does it control? and how can i prevent it from happening to my new ecu? also i read someone mentioned that my automatic 01 maxima has active motor mounts that may have a short somewhere? anyone have a pic of the engine bay layout so i know where this mounts are and how to check them? can someone help explain how to test my iacv? i have a feeling i need a new one but they are expensive and i'd really like to know if my old one is still functioning, thanks alot!!

 

Where are the sta509a's available for purchase?

I have had the same idle problem as everyone else on my 2000. IAC had antifreeze in it when I took it apart.
Looking in the ecm I am not seeing the burnt chips as in the pictures. Is there a way to test it before i reconnect it with the new IAC? Is anything else beside the IAC controlled by the chip that burns out?

You guys seem to be more electronically minded than I am. Is there any way to get a schematic for the ECM circuits?
Thanks.

 

My 2001 MAxima has the same problem as reported in this Forum.

I had a short IACV step motor (4-5). Replaced it (OEM $249) the idle still fail. So I took out the ECM and found out the MOSFET driver for IACV was burn out on pin-7 that connects to connector 4 at IACV. So the problem was clear that the short coil overloaded the MOSFET driver (SK STA509A).

Found the parts in Asian part suppliers. I bought the chip from utsource.net that delivers from Singapore. Took a while to get the part.
I replaced the chip and cleaned the circuit board to remove and carbon residual. Put it back in, start the engine... Problem fixed!

Oh, you need to perform the ECM learning procedure (EC-73, Basic Service Procedure See http://www.nicoclub.com/FSM/maxima/2001/) to get the idle speed correct.

Thanks for the posting in this thread! Hope mine could be a little help too.

 

What's the quickest way to get to the IACV. I tried to replace my iacv (nothing wrong with it, just preventative) today while I was doing several things to my car. It didn't seem like something I could get done in less than an hour, so I skipped it.

 

Do you think you could elaborate a little more as I am in the same boat. The dealer said my Idle motor is bad, and the ECU is also bad. I wanted to do the work myself, and then have them do the reprogramming so my keys work, and the idle relearn etc. Just wanted to make sure I was getting the right parts etc.

Also, if I buy a new IACV and replace it without a new ECU, can I damage the new IACV trying to run the vehicle, or will it be fine. I was going to purchase, here.
http://www.autopartswarehouse.com/sk...%26+Drivetrain

 

so after reading this thread ( which has some awsome nfo i vote sticky ) i came to the conclusion if you have an automatice trans. 5th gen, disconnect your electric motor mounts & replace IACV valve BEFORE it fries your ecu, and kif you drive a manual trans 5th gen. replace IACV before it fries ecu....is this right?

so i can order a new IACV

 

bueller? bueller?

 

this thread is indeed awesome. +1 wish i had found it before posting over on http://forums.maxima.org/5th-generat...ecu-bad-2.html

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. it begins idling erratically. pulled throttle body and tested IACV - correct battery voltage on harness pins 2&5 as well as correct resistance (22 ohms) on the IACV motor. i did not, however, test for shorts. i cleaned the throttle body and motor (electric cleaner only on the motor) and reinstalled.

pulled ECM today and, booyah - STA509A has blown a load:

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

i replaced the head unit a few months back and admittedly did not do a fantastic job shoring up all of the wires due to lack of maneuvering room (read: i may have caused a short somewhere).

i also replaced the crankshaft position sensor harness back in february as i cracked the existing one after hitting a pile of snow. i did a fantastic job protecting that circuit, though.

why oh why is the idle control not protected by a fuse?! i am now scared to replace STA509A, lest it just blow up again. new IACV is $200, but if that's not the issue, i'm just spinning my wheels.

where's the first place to test for shorts? can i make this easier on myself by testing the ECM harness?

 

can anyone post the ECU wiring/pins that control the IACV? I'd like to fuse that circuit instead of replacing the IACV if i could. I gues i could look up the wiring diagram on Alldata

 

I'd check from the ECU harness pins. You have a service manual, so trace the pins on the harness and check for shorts, then go from there.

 

Check out page1 on this thread.
http://forums.maxima.org/7007741-post38.html

 

page 432 of the EC section of 2001 FSM shows the following ECM->harness pinout for the IACV-AAC:

terminal 6 (pin 1; W/PU)
terminal 7 (pin 4; Y/B)
terminal 8 (pin 3; Y)
terminal 17 (pin 6; GY/L)

the two additional red wires (pins 2 & 5) are power.

you should check the FSM for your specific year, though.

 

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

If you are hesitant 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.

Check at the IACV connector for shorts, pins 1,3, 4 and 6 should not have any connectivity between them.

If you decide to install fuses, your best bet is to install them at the ECU bulk connector side of the wiring harness on pins 6,7, 8 and 17.

 

So let me get this right, wiring harness pins # 6, 7, 8, & 17 should all get their own fuse?

would a 10 amp fuse suffice? my guess is it should be enough fuse protection.


maybe a 15-20 amp fuse? And yes the best place to fuse is at the ECU connector, since anywhere in the circuit a short could occur, it's the ECU's last line of defense.


I'd rather replace a blown fuse than a fried ECU....

edit: anyone else agree?


sticky!

 

The STA509A data sheet states 3 Amps and 6 Amps when it pulse, so I would go with a 6 amp fuse and 7.5 amps should be the max and you are taking a risk.

 

bump

TTT for some great info

 

Does one have to do a key relearn or other lock out procedure if it's the original ECU that was pulled, repaired, and re-installed?

 

In addition to duanes7's question - anyone know of a place in the DC area that can repar an ECU? I'm having these issues currently (P0505, replaced IACV, idle all jacked up, bad ecu). I really don't want to spend 1g on a new one from nissan.

Anyone use this service (http://www.autoecu.com/) or something similar for repair?

If i try to go the local route and just get the STA509A chip put in, where are people ordering this chip from?

Help!

Thanks!

 

Has anyone seen a step-by-step of how to clean the IACV? I took mine apart this weekend and cleaned it. All works ok now, idles up/down with ac on/off, but IACV still seems a little slow to respond as it did before. Starts, but doesn't idle sometimes without giving it gas.

Had coolant leak possibly damaging the stepper slightly.

Is the flapper spring inside supposed to be preloaded? When re-assembled at the slack position, the flapper spring cover is just a few degrees to the left of its orig position.

My ECU is ok for now.

 

got my ECU repaired for $70 at autoecu.com... just got it back and put it in, works great. Much better alternative to buying a used or new ECU!

 

Glad to hear repairing ecu is that cheap.

I've had no problems with my IACV since a couple of days after cleaning it. Starts and idles fine now...

 

Hell yeah that's good to know I thought it would be a arm and a leg

 

Nakis, would I need a fuse to all 4 pins listed above to prevent the IACV short out or can I get away with just one?
Also, I see on my ecu I have 2 STA509 chips side by side. Does anyone else have this?

 

i've replaced the IACV and finally got three replacement STA509A chips. the tv shop didn't attempt to solder the 10 pin socket i had in case the IC blew out again. the chip is firmly attached to the PCB, and i'm scared ****less to reattach the IACV harness.

i've spliced the leads entering into the bulk harness for pins 6, 7, 8, and 17. i've put some butt connectors on there along with some 16g wire to extend the leads. they're dangling in the passenger compartment at the moment because i'm unsure of what fuses to use. i found some 6A AGC glass fuses at autozone along with some fuse holders, but the things are gargantuan. plus they're 12 gauge wire. and they're rated for 250Vac. i think they're intended more for power applications than circuit protection. i'm a bit of an electrical idiot, so i'm not quite sure what's appropriate to use. autozone has no 6A blade fuses. i've got 5A and 7.5A. cooper bussman sells 6A 12V circuit breakers for use in automotive applications, but i have no idea where to buy them.

i'll see what i can find at wal-mart, but i think i'll have better luck at a specialty electrical store. autozone sucks.

if i can find a smallish fuse block and some 6A blade fuses, i'll just mount a new fuse block in the center console and use that.

suggestions?

 

Did you have to replace 3 509A chips or just got extras?

 

i just got extras

 

i'm guessing from the utsource or something like that. the asian supplier, or somewhere closer?

 

i actually got the first one from a guy in new york (bgreywolf) from the following thread:

http://www.carsurvey.org/reviews/inf...6825/comments/

i bought the other two off of ebay from hong kong.

 

ok here goes:
removed engine mounts, replaced the ICV, and repaired the ECM with the chips above. took it to the dealer to re-key and it was still getting high-idle and P0505..

dealer suggest to replace the ECM.. found a used ECU and reprogrammed it.. nice low idle now and it seemed all good. 2 weeks later.. P0505 comes on and now not starting on crank. i have to step on the accelerator pedal until it holds an idle. when idle.. it sits firmly on steady revs and drives fine.. i just have problems during starting ..

any ideas? i am about to pull the ECM out again, but the dealer plugged it in very securely,i have to do it during the day.. i hope it is not fried, but it is not giving the same symptom as before..

i have unplugged the battery over night

 

Why did you have to re-key at the dealership if you didn't change the ecu?