dustey

iTrader: (1)

I've got a 2001 Maxima SE auto, 132k, no traction control.

Approximately 2 years ago, the ECM was replaced with a reman unit from Nissan. Due to a bad ISC valve, the ECM currently in my car is bad.

The numbers/code on the OE ECM was A56-P70 Z62. When I had the ECM replaced 2 years ago, the dealership just plugged in my VIN and that is how they ordered the correct ECM. I just pulled out the current ECM (the reman unit) and it is not labeled like the OE one. The code on it is C56-W56 ZS6K.

In finding a replacement, would ECMs with either code work?

Pilm

Sounds like you've had ECM's with both numbers and they worked, so that answers your question. So what's wrong with the current ECM, another IACV failure or something else?

dustey

iTrader: (1)

Yeah, kind of what I was thinking. Just trying to be as sure as possible due to the $$$ in replacing it.

The first time was a misdiagnosis. I had a misfire on a a certain cylinder and, long story short, we tried everything under the sun to fix it but nothing worked so it was concluded that the ECM was bad. It wasn't, it didnt fix the misfire, but it was too late to get the old ECM back as the core was returned to Nissan at the time of purchase of the reman unit. An expensive mistake.

This time it is the ISC valve that did in the ECM.

Pilm

Most times the ECM can be fixed by simply replacing the STA509A mosfet, that's what I did and it only cost me $15 for a new mosfet off eBay.

Stru

It's possible, but sometimes the electrical short is so bad that it burns a hole in the motherboard (like mine) and in order to repair it, you'd have to install jumpers and pretty much turn your motherboard into a mess. It'd be better to just get a junkyard one for a couple hundred bucks.

As for the code on the motherboard, I don't think it matters too much if your car has no TC. If your motherboard supports TC and your car doesn't, your car should still function just fine. But if your car has TC and your motherboard doesn't support it, your TC won't work (obviously). Just remember no matter what ECM you put into it, it'll have to be towed to a dealership and reflashed.

OH, and make sure the ECM is the LAST thing you install. Replace your idle air control valve, throttle position sensor, and unplug your motor mounts (just in case) before you install it, because if any of them are fried you'll end up back to square one. Good luck!

Pilm

The problem with junkyard parts is you are buying something you have no idea if it works or not. It's possible you'll get a working part, but for the ECU, not only do you pay $200, but you also have to pay another $120 for reprogramming at the dealer, so it's an expensive solution. A $15 part off eBay is far cheaper and has a 90% chance of fixing the problem (Stru was obviously one of the few who had catastrophic damage, but based on feedback on these forums, his was the exception, not the rule).

I also don't recommend putting any money into the TPS unless you've removed it and KNOW it's bad. Why replace a part that only has a 5% chance of being bad, unless you are loaded with spare cash.

Replacement order isn't important, what is important is replacing all the damaged parts before starting the car again! And be sure to disconnect the battery anytime you remove the ECU or disconnect electrical connectors, better to be safe than sorry!

dustey

iTrader: (1)

The funny this is, the ECM case looks perfect. I didn't open up the case itself to see how the board looked though. Regarding the numbers, I'd prefer to match up the numbers, to be on the safe/easy side. I have found (what appear to be) good ECM's on eBay with matching numbers and a good return policy so all other variables the same, I would much rather get a matching numbers unit. But, for the right price, it would be worth trying a non-matching numbers unit if the donor car had the same stats.

To add more into the mix (which may or may not be relevant), the car still runs after installing the ISC valve with the "bad" ECM. The ISC valve was replaced at the dealership, looked it up to the CONSULT III, and it wouldn't relearn the idle. Keeps giving an error message. Everything was taken apart and put back together to ensure it was done properly and still it won't relearn the idle. The Nissan tech is a friend of mine who has worked there for probably 8+ years so I am not doubting anything he has done. The idle was acting a bit funny for a while but only briefly when the car was cold, in the cold, so I just chalked it up to one of those things older cars do.


Is there a how-to regarding replacing the "STA509A mosfet" for a guy with no soldering experience?

Pilm

The post that helped me was one by nakis: http://forums.maxima.org/6966447-post29.html

He shows 3 pix, first one with 10 pin chip removed where you can see the black marks on the pc board where the chip fried. In the 2nd one he shows pic with new chip installed. It's very straight forward. If you don't know how to solder, check out youtube, they have dozens of vids on soldering pc boards. First thing to do is remove the cover on your ECU and look for the mosfet, it's located near the connector (use nakis' pic as a guide to find it), or post a pic here.

dustey

iTrader: (1)

I popped open my ECM and found this next to the chip previously mentioned.





I was able to get a used reman'd ECM from another user for a good price which doesn't have the above damage.

Pilm

Don't throw your ECU away, it's easily fixed, and you could sell it to someone else for $150 or keep it for a backup.

Amerikaner83

iTrader: (17)

That little trace? Hell, I fix those all day, that's NOTHING. Keep it, fix it, sell it, Profit


Get a new MOSFET and get that trace jumpered and you'll be golden