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The STA509A integrated circuit has 4 transistors built into one chip. One STA509A chip is used for the IACV and a second chip is used for the electric motor mounts on an automatic trans car.
When coolant leaks into the IACV stepper motor, it creates a short circuit that causes more electrical current to flow through the STA509A chip and the chip overheats and burns up.
The same thing happens when the electric motor on the electric motor mount shorts out.
But how does a motor mount "backfire"? It does not have combustion. It is an oil pump run by an electric motor.
The STA509A integrated circuit has 4 transistors built into one chip. One STA509A chip is used for the IACV and a second chip is used for the electric motor mounts on an automatic trans car.
When coolant leaks into the IACV stepper motor, it creates a short circuit that causes more electrical current to flow through the STA509A chip and the chip overheats and burns up.
The same thing happens when the electric motor on the electric motor mount shorts out.
But how does a motor mount "backfire"? It does not have combustion. It is an oil pump run by an electric motor.
The engine mounts short out the STA509A chip by the NEC chip? How many STA509A chips in the ECU?
Last edited by maximatech12; 07-26-2016 at 05:26 AM.
I think I saw STA509A + mosfet on 1 of the chips when I pulled my ECU. There is another similar type chip that reads "NEC" as far as the other two chips close by I'll have to pull it again and look. they meed a PITN character
is there an easy way to get the 8mm nuts removed?
I think I dropped one fell behind the carpet and vanished.
Last edited by maximatech12; 07-26-2016 at 05:26 AM.
When Bridgestone replaced the IACV on my 01 Maxima back in 2011, they mentioned they could not re-learn idle. It had to go to Nissan.
after the P0505 flashed the car felt as though it blew a power transistor, I was able to drive but it just was if I was running on 3 cylinders.
If the STA chip associated with the IACV was burnt would the car even be able to drive?
I didn't smell any burnt smells.
Instead of having a tow I even drove it from Bridgestone to Nissan after the new IACV was installed.
Just a comment to ad on the IACV/ECU failure in the 01 maxima.
When Bridgestone replaced the IACV on my 01 Maxima back in 2011, they mentioned they could not re-learn idle. It had to go to Nissan. don't know why. The procedure is in the service manual, you can do it yourself.
Statement 1 after the P0505 flashed the car felt as though it blew a power transistor, I was able to drive but it just was if I was running on 3 cylinders.
Statement 2 If the STA chip associated with the IACV was burnt would the car even be able to drive?
I didn't smell any burnt smells.
Statement 3 Instead of having a tow I even drove it from Bridgestone to Nissan after the new IACV was installed.
Just a comment to ad on the IACV/ECU failure in the 01 maxima.
In the section I labeled as statement 2, you are asking a question.
In the sections I labeled as statements 1 and 3, you answered your own question.
Yes, all 5th gen ECUs have the STA509A integrated circuits, not just the 2000 and 2001.
Unless you have a sophisticated ECU tester that you can plug the ECU into, you will have to open the cover on the ECU and look at the chips.
You can buy new ones for between $5 and $10 so it seems like a lot of work to de-solder from one ECU and re-solder it into another. Plus too much heat from all that soldering has the possibility of destroying the chip.
Thanks, Dennis. Yeah, I don't plan to try to solder it myself if this happens again. I could maybe get the chip out...maybe...but getting all those solder points hot and soldered at the same time and getting the chip in there before they cool down and making sure there's connection on all three sandwiched boards...I have no idea how to do that. I just pay a TV repair shop near my house to do it for $50. $100 if they have to first pull the chip from another car's ECU. The shop said they have a $35,000 machine they use to pull those chips off. I'm sure there are much cheaper ways, but damn that's a lot of money. lol
I had to open the cover to check the chips. I used the chip that looked the best...and I didn't have much of a choice anyway because the 2000 Maxima I pulled the ECU out of had no STA509A chip in it. Instead, it had two STA508A chips and the board was configured differently. I still can't figure out why it was different. Thanks for letting me know all of the 5th Gene have the STA509A chip, though. That's helpful in case I have to do this again.
I Google buy STA509A a few days ago. I couldn't get one delivered to me quickly enough unfortunately. Oh well. No big deal. I'm ordering two now, just in case I need them in the future on short notice. lol
I work with components like these in my day job. After hearing all the talk here about difficulty unsoldering the part, I thought it must be a four-sided, fine-pitch IC with 64 pins. When I downloaded the datasheet though, it turned out to be a simple SIP with 10 pins. No way does this require a $35K machine to unsolder. There are at least three techniques to remove this part, and the most expensive I know of would be a $500-1,000 vacuum desoldering station.
The real problem I see with the fried IC in the photo is the likelihood of board damage from the heat. The conductors on top and/or bottom may be badly burnt, and the pads are probably only loosely cemented to the board at this point. This takes a lot of extra care at this point to remove the part without further damage to the board. Regardless of how the shop does it, $50 is not excessive for this job.
It may be a ground issue to begin with. I was under the impression that the only way this could happen is if a ground was faulty.
There is a Grey/purple wire coming into the small motor from the ECM and then a Yellow & Black wire. On the other coil it's a yellow wire and then a White and Purple wire. I guess the one coil control the open and the other controls the closing of the valve?
Yeah, I know there are other cheaper methods because some of the guys here on the forum say they've done it at home with some soldering equipment. I'm assuming they have some decent equipment, but nothing crazy expensive. And I was pretty pleased with the $50 per chip removal and replacement (they charged me $100 because they had to remove two chips and then swap one into the other computer, so it doubled the price). I figured that was a good deal. They did it in less than two hours, too, despite their being really busy.
Thanks for the input! Good to hear it from someone who does this kind of thing for a living.
It may be a ground issue to begin with. I was under the impression that the only way this could happen is if a ground was faulty.
There is a Grey/purple wire coming into the small motor from the ECM and then a Yellow & Black wire. On the other coil it's a yellow wire and then a White and Purple wire. I guess the one coil control the open and the other controls the closing of the valve?
Suggest you get the Nissan FSM for the 2001 Maxima and look at page EC-432.
You will see that the IACV has 6 wires going to it, 2 12 volt wires (both red) and 4 control wires (yellow, white/purple, yellow/black and gray/blue). There is no ground wire, as there is no need for ground. Ground is supplied by the ECU through the 4 control wires that go to pins on the STA509A chips.
While Nissan used several different layout of the ECU printed circuit board They are interchangeable as long as the car options match.
While Nissan used the STA509A chip, the STA508A chip is a plug compatible replacement that can handle twice the current of the STA509A.
Damn. The first ECU I got had two STA508As I could've used! But none of the threads I found said they could be used. That would've saved me a lot of time and $38 more. Oh well. At least I know what transistor array to use next time. I still have the ECU with the two STA508As. Thanks, man.
FWIW, Amazon lists the Sanken STA509A (but not the 508) for $9.80 and free shipping. There are a few STA508As on eBay at similar prices, although I would be concerned about counterfeits. In any event, I don't think it's necessary to buy another ECU just for this part.
Based on the datasheet, this IC could be replaced with discrete components in a pinch. Apparently, someone else has done exactly that - I found this image on the Net:
FWIW, Amazon lists the Sanken STA509A (but not the 508) for $9.80 and free shipping. There are a few STA508As on eBay at similar prices, although I would be concerned about counterfeits. In any event, I don't think it's necessary to buy another ECU just for this part.
Based on the datasheet, this IC could be replaced with discrete components in a pinch. Apparently, someone else has done exactly that - I found this image on the Net:
Get 'er done!
Yeah, I don't recommend people get a junkyard ECU to get the transistor. I did it because I needed the transistor within a day or two so I could fix the car and use it on a business trip. That's all. I ordered some back up transistors to keep on hand just in case I need to fix this issue quickly again for some reason.
While Nissan used several different layout of the ECU printed circuit board They are interchangeable as long as the car options match.
While Nissan used the STA509A chip, the STA508A chip is a plug compatible replacement that can handle twice the current of the STA509A.
Hey, DennisMik,
I just talked to the TV shop owner who was helping me with the STA509A soldering. He said the STA509A was the one that could handle twice the voltage. But I think he's getting confused. I think I remember him saying the STA508A was the one that could handle twice the voltage. But I don't know who's correct.
Can you confirm which one handles twice as much voltage?
Is the one that handles twice as much voltage the one that's best to install so it doesn't go bad so easily?
The STA508A is the one that can handle the most current (amps).
The STA508A is rated at 6 amps steady and 10 amps surge/pulse,while the
The STA509A is rated at 3 amps steady and 6 amps surge/pulse.
I have attached the spec sheets for the 2. Look in the box in the top left corner, the 3rd and 4th lines down.
The STA508A is the one that can handle the most current (amps).
The STA508A is rated at 6 amps steady and 10 amps surge/pulse,while the
The STA509A is rated at 3 amps steady and 6 amps surge/pulse.
I have attached the spec sheets for the 2. Look in the box in the top left corner, the 3rd and 4th lines down.
It is time for my ST509A replacement. Thanks to the valuable info on this page, I know what to do. One mechanic at an autoshop, told me that I could possibly get away without any soldering, by using a two sided female connector, and cutting off the old/burned ST509A from the board still leaving its pins in the board, and connecting the new STA509A pins to it via female connector. Has anyone tried this?
It is time for my ST509A replacement. Thanks to the valuable info on this page, I know what to do. One mechanic at an autoshop, told me that I could possibly get away without any soldering, by using a two sided female connector, and cutting off the old/burned ST509A from the board still leaving its pins in the board, and connecting the new STA509A pins to it via female connector. Has anyone tried this?
I'll give my two cents. Judging from the lack of clearance from the board to the solder and solder to the chip, my guess is that it would be very difficult to get a tool in there to cut each individual prong.
Next, you have the problem of whether there's enough of each prong sticking up out of the solder to actually connect to. If you only have a tiny prong, that won't be enough to connect to. If you manage a connection that's not truly solid, you'll risk a harsh bump knocking something loose, unless you can somehow manage to solder each prong very solidly, but there'd still be no guarantee it would hold.
If you think none of those issues will be a problem for you, then I say go for it and let us know how it goes.
Personally, I recommend fully pulling the old chip and putting in a new chip the normal way so you'll never have to do it again and you won't risk breaking any circuitry in the IAC (or maybe it's the throttle body...I forget). Better safe than sorry, but you can do whatever you like, of course.
Maybe someone here with more experience can give a better answer. Good luck!
Ill tell ya with this issue in these Maxima's they really coulda made this damn thing easier to get to!
I wanted to pull the TCM to check it and its buried behind the damn radio.
Relocating this ECM under the glove box may make it easier to pull.
07-24-2016, 07:37 PM
