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01 Maxima ECU self destructs, blown IACV, electronic motor mounts Forums > > 01 Maxima ECU self destructs, blown IACV, electronic motor mounts 01 Maxima ECU self destructs, blown IACV, electronic motor mounts
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  #1  
Old 06-30-2009, 03:34 PM
jh15 jh15 is offline
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Default 01 Maxima ECU self destructs, blown IACV, electronic motor mounts

2001 Maxima Gle A33 Auto, 3.0L 6, Bose, trunk CD changer soon to be tossed for mp3 input.
Original owners. New to me, was wife's car, now mine after she bought 2008 Altima 3.5.

Greetings. For the past week straight, I have been in crisis mode and posted a couple things in another forum, forgetting I had subscribed here. Now I have a brief respite while awaiting parts.

I have a couple questions, and will ask the gurus for my best angle of attack. I have spent many hours searching other forums, here, and Google, plus Ebay learning more every day what a quagmire I have gotten myself into.

Boils down to: Car was fine till last fall, get abs light, I put my scanner on and ignore the bad right rear wheel sensor till warmer weather, and/or a thing to tackle during another repair. (Not missing ABS, wind bags or other modern stuff as having 2 other 20 year old vehicles without those luxuries).

1. Have I been hearing engine mount buzz for last several months? Soon after the ABS light, but not right after, I would turn key on and hear a pronounced buzz under the hood. Since I rarely drove 'her' car, I thought it was just 'stuff' defaulting to start positions, throttle valves, a/c dampers etc. Later I would see things in service manual that certain buzz of IAC was normal, and to this week I had thought it was "unloading of ABS pressure, due to being in disable/fault mode."

Where I read that I couldn't find again. I never heard sound with engine off as others with mount problem.
Car quickly self destructs last week, so here I am.
I have new IACV body assembly to replace the one with measured shorted stepper motor.
I found just today what looks like a reputable rebuilder for the (blown chip in) ECU, although I just got IC chip in today I was planning to replace myself.

Had I found him last week, I'm sure I would have had ECU out to him and back by now.
Need to know after tiring of hours of searching not in any order: 1. TSB says my ECU has an updated program. So would that be absolutely necessary to prevent recurrence? or is it just a performance issue. I can only scan and turn off mil and a few running gauges with my tester.

2. Will the new stepper, if being out of range, bottomed out while in the process of of the learning sequence, and the time it takes to learn cause the new stepper to overheat, then blow ecu? I've seen better stepper driver chip protection in $40.00 vcr's and furbys.

2a. Do I need to preposition the pintle beforehand of the learning? I will reluctantly dig up my Heathkit Hero1 robot or build an Arduino board to do, if needed.
I was thinking of putting a 2.7a IC protector in each +vcc half of the IACV chip, and possibly the motor mount chips, but since they are not exploded like the '509 idle chip, I'll just unplug the mounts.

The dealer had neither of the gaskets for the throttle body to engine, if they don't come in soon can I reuse? Gasket cement? (I know I should stay away from any silicone sealer.)

Since I haven't touched the ECU pcb yet, should I send it to be rebuilt? They give a lifetime warranty, $75.00 flat rate, and free return shipping. But they say I must also replace the TPS, which measures OK. They don't mention anything about exploded motor mount chips as I saw in other forum. Mine are ok.


As for replacing the '509 chip, I have a new one, don't know if the other mount driver chips are ok, yet, will measure. Those I could only find by querying a plant in china, though it looks like they sell single unit quantities.
I used to be mil spec solder certified, I have esd safe lab coat, wrist strap, and workstation in my shop, but before I attack it if you guys say send it for rebuild and warranty, I will.


Enough, if you read this far, I thank you, don't shoot the noob for rambling, but been hours and hours researching what I thought would be a 'new' reliable old car. Dang.

With two of these Nissans in the barn, I'll be hanging out here to help others from now to eternity.
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  #2  
Old 06-30-2009, 06:05 PM
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Quote:
1. Have I been hearing engine mount buzz for last several months?
Yes, that's probably the cause. Just disconnect the mount to stop the buzz, since is probably to late to save the ECU. You probably will feel no difference by disconnecting the mounts.

Quote:
2. Will the new stepper, if being out of range, bottomed out while in the process of of the learning sequence, and the time it takes to learn cause the new stepper to overheat, then blow ecu?
Very unlikely, I think it was just a poor design that was making the valve fail and damaging the ECU.

Quote:
2a. Do I need to preposition the pintle beforehand of the learning?
No, just set the idle after the installation.

Quote:
The dealer had neither of the gaskets for the throttle body to engine, if they don't come in soon can I reuse?
Just be careful when removing the body, if is coming apart you should wait to install a new one from the dealer.

Quote:
Since I haven't touched the ECU pcb yet, should I send it to be rebuilt?
I Never done that, can't comment.
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  #3  
Old 06-30-2009, 06:35 PM
jh15 jh15 is offline
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Answer I don't have, once I re-install new iavc, throttle body, if the learning procedure takes too long, and the pintle pegs, will the stepper or ECU blow itself up if it takes too long. If I install IACV chip myself with IC 2.7 amp protectors, maybe I can contribute data.

But then I would be sending a modified ECU to the alleged rebuilding guy.
Disclaimer. I am tired, it is late and I am not angry, take into consideration. throw info at each other.
I don't have ebay address google iacv rebuild, he looked good only bad feedback was customers did not fix what he told them to. the parts fry each other. Even cheap toys have better motor control protection.
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  #4  
Old 07-20-2009, 06:44 PM
jh15 jh15 is offline
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I am back at work on my car. Took three weeks to get hoses and gaskets from Nissan dealer here in southern Maine, which I was at freedom to wait for, as we were traveling, have other vehicle.
I thought I'd post tech info here as I'm working. Maybe some poor soul googling might come onto say, "how the throttle sensors work" etc.
So if the mod gods ok it, I'll be posting tables of info here, then I hope make a summary, put solved in my subject line.
Thanks to the rice wagon guides, now if the Japs could make non rusting cars, would go over better than any hybrid...
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  #5  
Old 07-20-2009, 06:57 PM
jh15 jh15 is offline
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Stuff found recently: " My Maxima 2001 '01 throttle body", not dbw, drive by wire.
Throttle position sensor: to connectors, one a pot, or potentiometer, the other a switch.
Two connectors go to this round plastic choke spring looking case. (showing my age). This is on opposite side of shaft from the throttle/speed control cables.

If you have the throttle body and attached IACV on the bench, Then the "A" connector is on the left.
This is all my nomenclature for now.
Pins A 1,2,3 and B 1,2,3 are the connectors as you look at them with the throat above them on the bench. In the car, A would be the lower connector.
The center of each 3 pin array I call the common.
Put your ohmeter common probe clip there. (with connectors to the car unplugged).
Here is my stuff:
To be continued, maybe tomorrow.
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  #6  
Old 01-31-2012, 08:56 PM
martydew martydew is offline
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Several places on this forum there is a suggestion, when replacing the ECU, to leave the motor mounts unplugged. My 01 Infiniti I-30 is at the dealer, they just replace the ECU and I asked them to leave the motor mounts unplugged. The dealer service tech is telling me he can't set the idle with the motor mounts unplugged. Hence he says he needs to replace the motor mounts and connect them to the ECU.

What should I tell the dealer? Is there a way he can set the idle without plugging in the motor mounts?
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  #7  
Old 02-01-2012, 06:24 PM
jh15 jh15 is offline
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Hello,

I went through the whole idle learn procedure without any reference to the mounts.

The idle learn procedure set the idle so from no load to full load (alternator drawing, a/c on) at idle, the speed will be regulated to 850 rpm or whatever the idle spec is.

The mounts are turned on or off by engine speed, in other words they "listen" to the computer "talk" to them.

I don't see any way they would affect the idle learn.

Maybe in newer cars you can't do the preventive work-arounds, but my 2001 is fine with them off.

The actual learn procedure is quite simple, it just looks wordy. Once you do it, you could do it in your sleep.
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  #8  
Old 02-02-2012, 02:45 AM
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Quote:
Originally Posted by martydew View Post
Several places on this forum there is a suggestion, when replacing the ECU, to leave the motor mounts unplugged. My 01 Infiniti I-30 is at the dealer, they just replace the ECU and I asked them to leave the motor mounts unplugged. The dealer service tech is telling me he can't set the idle with the motor mounts unplugged. Hence he says he needs to replace the motor mounts and connect them to the ECU.

What should I tell the dealer? Is there a way he can set the idle without plugging in the motor mounts?
Yes. We do it quite often. The mounts have nothing to do with the idle relearn. They are just trying to sell you more work.
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  #9  
Old 02-02-2012, 03:04 AM
jh15 jh15 is offline
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What will a dealer-replaced ecu and IACV cost you?
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Old 02-02-2012, 05:13 AM
martydew martydew is offline
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mpe235 and jh15,

Thanks for your responses. I insisted the dealer service not reconnect the motor mounts. (this was after the burnt out a 2nd computer when they connected to the motor mounts -- I had told them not to.) They said they idle was fine and they didn't need to adjust it. In any case they didn't replace the motor mounts. The replaced the Engine Control Module and the Throttle Body Assembly. It cost $2,300.
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  #11  
Old 02-08-2012, 05:13 PM
flamax flamax is offline
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I am trying to disconnect the engine mount connectors on my 01 Maxima, but I'm having a difficult time getting them apart. Most connectors have a tab you press in or down, so you can wiggle the two sides apart, but these are different than most of the other ones that have a large green tab. So anyone got any advice, do these have a tab, and does it push in or down? I'm surprised I need to ask this, but at this point getting the ECU out of the car has proved simple compared to this!

Last edited by flamax; 02-08-2012 at 05:35 PM.
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  #12  
Old 02-08-2012, 05:19 PM
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Quote:
Originally Posted by flamax View Post
I am trying to disconnect the engine mount connectors on my 01 Maxima, but I'm having a difficult time getting them apart. Most connectors have a tab you press in or down, so you can wiggle the two sides apart, but these are different than most of the other ones that have a large green tab. So anyone got any advice, is there a tab, and does it push in or down? I'm surprised I need to ask this, but at this point getting the ECU out of the car has proved simple compared to this!
You have the wrong connector. The motor mount connectors are brown.
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Old 02-08-2012, 05:37 PM
flamax flamax is offline
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Originally Posted by mpe235 View Post
You have the wrong connector. The motor mount connectors are brown.
Yes, these are brown with 3 wires (I only mentioned the large green tab because other connectors have that, but these small brown ones don't seem to have tabs, or if they do are they tiny ones)?
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Old 02-09-2012, 02:25 AM
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Originally Posted by flamax View Post
Yes, these are brown with 3 wires (I only mentioned the large green tab because other connectors have that, but these small brown ones don't seem to have tabs, or if they do are they tiny ones)?
The brown connector does have a small tab that needs to be pushed in. It is easier if you use a screwdriver to press it.
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Old 02-10-2012, 08:36 AM
flamax flamax is offline
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Thanks mpe235. I found needle-nose pliers very helpful in finally getting these disconnected, esp. the one for the rear mounts.
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