All,

I own a 2001 Maxima GLE. Automatic with climate control with 140k miles. Have an electrical burnt smell in the cab, studied this forum and figured either my IAC valve or motor mounts have smoked a component in my ECU. Pulled my ECU and found a smoked component. Looks like a different component than most ones I see on this forum and the net. Does anyone know what this component controls (see attachment)?

Thanks,
Ed

 

No clue. And I'm not downloading your virus. Cheap ECU's on ebay.

 

No virus, I was trying to get the picture to upload. My understanding is I'm better off to get this ECU repaired vs buying a different one so that the key relearn etc. is not required. Also, if I don't know what caused the ECU component failure, I will likely cause the same issue again don't you think?

 

That's a bit hard to pinpoint since the ECU has so much it controls. What else happened to your car when this happened? Did the car still run? How was the engine idle? Cluster lights, any check engine or other warning lights come on? I would venture to guess your car (prior to pulling the ECU out of the car) did not operate, but determining what's actually happening to the car can better point to the culprit. If it matters at all, repairing an already damaged ECU will merely result in another component going awry, or the same part failing. The units are not expensive nowadays, and relearn process takes all but a half hour at most when done properly -- if even that long. I don't see that being a detractor here for avoiding a new ECU purchase versus saving some $$ to repair one that may fry sooner.

 

I smelled smoke inside the cab. Traced it by nose to the ECU. Removed the ECU and found this smoked component. Car runs fine, no check engine lights, everything works. This is precisely why I'm looking for what this component controls. Looking more on this forum, I found a couple of other posts where people had the same blown component. In every case, they had a 2000-2002 automatic car and had no check engine lights. I suspect this controls the adjustable motor mounts which I plan to disconnect. I would like this confirmed.

 

Ahh, gotcha. I have read the adjustable mounts have been reason for some other component failings. But I have not had this experience personally. Hopefully someone with more knowledge chimes in. The ECU controls the IACV, and other electrical components. Your airbags, and any sensors are all controlled by the unit. Is there anything written on that piece you could share? Perhaps a google search would return what that part specifically accounts for.

 

 

I did several different searches with both piece numbers and the only results were for ebay ECU sales.
I found this: https://circuitboardmedics.com/maxima-ecm-repair/ considering a refurb was brought up (in case anyone has had experience doing this, or you still wish to go this route first). Anyone better inclined able to delve deeper into this?

 

Repairing looks twice as expensive compared to just buying another ECU. Just get another and swap it in.

 

Could be, the question still remains. What does the blown component control? If I purchase another ECU or get mine repaired, I risk smoking it again if I don't know what caused the issue to begin with. If all it controls is the adjustable motor mounts, I will just reinstall the ECU with the smoked component.

 

no idea, historically toasted ECUs result from the motor mounts or IACVs shorting out from moisture. Disconnect your mounts and replace your IACV and you likely wont have this issue again.

 

I've got a new hitachi IACV on order along with manual motor mounts. They should be at my door on Monday. Hopefully someone chimes in that can confirm what the ECU component controls so I can just reinstall my ECU as is.

 

Without a circuit diagram, it is impossible to answer your question.
However, if you don't have the dreaded P0505, and assuming your car is idling fine, then it's reasonable to assume that the burnt-out transistor used to control your engine mounts. It is not known what would happen if you don't replace that transistor (again, not without a circuit diagram of the ECU). You can try - all of us would be very much interested in the outcome.
Finally, if you haven't read my document about ECU failure prevention, read it (link in my signature).

 

There are some fairly beefy traces coming off that component. Two of them are likely grounds. The other two you might be able to trace to the pins. If not, there are no more than 20 relevant pins you could check continuity with a multimeter. Grab the pinout from the FSM and you're off.

I'd recommend a replacement ECU once you find the offending device/wiring and repair it. Key relearn isn't hard, should be able to do it with Nissan Data Scan

 

I do not have a factory service manual. Does anyone have a screenshot of the ECU pinout for a 2001 Maxima GLE?

 

I found the NEC MOSFET transistor on Octopart. $3. I'm going to remove the blown unit and see if the car starts and runs fine. If it doesn't, I install a new MOSFET.

 

First i have a lot of ecu's and second i am bothered when people don't put their location in. You can put it in above the avatar. See in mine. People can help if they know where you live.

Also unhook both motor mounts and cut them off the plugs . People like to reattach them at shops without you knowing. Next get a New IACV and bypass the coolant.

 

Update: I installed the ECU back in my car with the NEC MOSFET removed. No smoke smell, no check engine lights, seemed to drive fine on my way to work this morning. I've ordered engine mounts from a manual car that I will install once received. Will post back with results.

 

You don't need new mounts just unhook them.

 

True if mine weren't damaged.

 

Good job. Now in a week or so your sunroof is gonna take a $hit. Happy motoring!

 

I sure hope not!

 

Just an FYI, aside from the mounts, the IACV was a common issue for 2001 Maxima's as a culprit to fry the ECU. I initially had a fried ECU in my '01 SE and it was replaced without any thought to pinpoint what was causing it. Turned out it was the IACV after that second ECU also fried. If your RPMs start bouncing profusely while at idle, or idling high, that may be the reason. Just an FYI. I hope not, and this was the solution to your problem. Good work!