y2kse

iTrader: (1)

I took this from an article in the June edition of Sport Compact Car:

". . . we reset the ECU by disconnecting the battery. Electrons remaining in the system were purged by stepping on the brakes, leaving the ECU with no memory."

Now if I'm reading this correctly, you don't need to disconnect the battery and leave it disconnected overnight to completely reset the ECU. All you have to do is disconnect the battery and step on the brakes. If that's the case, you should be able to completely reset the ECU in a matter of minutes rather than a matter of hours.

Pretty slick, huh?

KLOOGY

iTrader: (12)

So , does this mean I can put 235/40's on my 17X7's......LOL/////Just kidding !

y2kse

iTrader: (1)

Yup. But first you have to let me purge your electrons. And that's gonna hurt!

max_speed97

iTrader: (20)

will this work for the 4 generations also???

skyjay617

iTrader: (1)

what page???

y2kse

iTrader: (1)

I don't know why not. The article was written about a Subaru WRX.

y2kse

iTrader: (1)

Pg. 212, center column, second paragraph.

max_speed97

iTrader: (20)

maybe its only for the wrx and not other cars..???

y2kse

iTrader: (1)

I don't think electrons behave differently in a Maxima than they do in a Subaru.

Menasor

iTrader: (2)

I read in some post that when you disconnect the battery to reset the ECU, you are not actually resetting the ecu. I have heard that it is best to reset the ecu when you go to the dealer for service if you caused a malfunction on the car. For example, I am racing and suddenly something is wrong with it. If I go to the dealer hoping to get it fix under warranty for something that was obviously my fault then they have a way of knowinf without you telling them. i guess when they hook up the car to a computer it tells them exactly when the when the error code came up. For example if I get a code for a certain transmission malfuction, the technician can see at what speed, what gear, what rpm, how open the throttle was at the time of the malfuction. basically it tells them whether you were abusing the car. So by resetting the ecu all these things are not recorded for the tehnician to know whether the car was being pushed to hard. Does this make sense? What do you guys think?

adman

Yes, they do!!! They are slower...


ADMAN

Tony Fernandes

OMG ROTFLMAO!!

Tony

y2kse

iTrader: (1)

I'm not sure about that, Menacer. Error codes such as the one you're describing may be stored in non-volatile memory. If that's the case, disconnecting the battery may not eliminate them. But disconnecting the battery returns many ECU parameters back to their default settings. The default setting of the SES light, for example, is OFF. So disconnecting the battery may eliminate the SES light even though the error code is still stored.

A variety of reasons exist for resetting the ECU, not all of which involve a tripped SES light. The ECU should be reset any time you install a major performance modification such as an aftermarket intake or a Y-pipe. Resetting the ECU places it in learning mode and reduces the risk that the modification will generate a SES light when power is restored.

FWIW, I'm convinced that the information presented in the Sport Compact Car article is correct. It simply makes sense technically.

Anyone who resets their ECU by disconnecting their battery and letting their vehicle sit for hours on end is wasting their time. Just disconnect your battery, step on your brakes, and voila . . . mission accomplished.

2002 Maxima SE

iTrader: (3)

[quote]Anyone who resets their ECU by disconnecting their battery and letting their vehicle sit for hours on end is wasting their time. Just disconnect your battery, step on your brakes, and voila . . . mission accomplished.[quote]

All this achieves is draining out any charge that is left. You can also:
Disconnect battery and
1)Leave your lights on.
2)Leave your radio on.
etc

Brakes have little to do with it, other than lighting up the rear lights.

y2kse

iTrader: (1)

[QUOTE]Originally posted by 2002 Maxima SE

Quote:

All this achieves is draining out any charge that is left. You can also:
Disconnect battery and
1)Leave your lights on.
2)Leave your radio on.
etc

Brakes have little to do with it, other than lighting up the rear lights.

Agreed, 2002 Maxima SE. I think it's just a matter of which method is the quickest. I assume that Sport Compact Car's Subaru WRX had lights and a radio. Yet they chose to drain the electrons by stepping on the brakes. That's good enough for me.

But those in a REAL hurry could always leave their lights on, leave their radio on AND step on the brakes.

dblrr900

I am almost possitive it wont work on the 2k2. Every other car I have had I can reset the ECU is some fashion (either by switch, wire, ground, or pulling the battery) but I have tried everything on my 2k2 and the only way it happened was by driving it until I hit @ 50 restarts. Maybe when I get bored I will trip my ECU and try this, but I highl;y doubt it will work. They did something new with these ECUs.

y2kse

iTrader: (1)

Try it and let us know what happens, dblrr900.

dblrr900

OK, let me get bored first...

2002 Maxima SE

iTrader: (3)

The ECU probably has a small battery attached to it that is constantly charged. That way, in case the main battery is disconnected for service, the ECU will not lose any memory. This would be similar to the extra battery on Palm's to prevent memory loss when the AAA batteries die and need replacing.

y2kse

iTrader: (1)

That's possible, 2002 Maxima SE. But some types of memory are non-volatile even without battery backup. ROM (read-only-memory) and nvSRAM (nonvolatile Static Random Access Memory, for example, retain their settings without battery backup of any kind.

Max_Gator

Funny thing, my SES light came on for the first time ever last week. So, when I got home that night, I disconnected the battery - positive cable - and left it overnight. Left the hood down but not latched to fix in the am.

The next morning, hopped into the car and started it up - without reconnecting the battery! Then noticed the hood was up and thought - gee I need to reconnect the battery - and turned the car off. Only then did I realize that the car started with the battery disconnected.

SES light went off and stayed off, though.

victor

iTrader: (1)

hmm, that's weird, i wouldn't think a car could start without the power from the battery. i think i'm going to try it out.

but with the resetting of the battery thing, i've also heard about disconnectiong the battery, and then proceeding to turn your lights on, and that should drain the capacitors and all the power from the system.

y2kse

iTrader: (1)

Fascinating. That brings up a couple of questions.

First, if there's enough juice left in the electrical system with the battery disconnected to start the engine, is there enough juice to prevent the ECU from resetting itself?

Second, how long would you have to step on the brakes (or leave the lights on or leave the radio on or all three) with the battery disconnected before enough juice drains from the electrical system to prevent the engine from starting?

It might be interesting to run some experiments if someone has the time and the desire to do so.

Max_Gator

I wonder if it is related to the feature that provides power to open/close windows, etc. once you have turned off the engine but have not opened and closed the door.

y2kse

iTrader: (1)

Yup. Same general idea as stepping on the brakes. Although the Sport Compact Car article didn't state it, I assume you'd need to keep the brakes depressed until the brake lights went out (or keep your headlights on until they went out, or both) to completely drain electrons from the electrical system. One way or the other, however, a combination of one or more of these techniques should be faster and more thorough at draining residual electricity than the currently preferred method of simply letting the car sit overnight with the battery disconnected.

Maksim2000

iTrader: (4)

I've tried the brake trick after my CEL came on and it didn't work... light stayed on after I've re-connected the battery. Now leaving it disconnected for about an hour did reset the light...

acMAX

cool!

and thanks!

this could be very useful.

y2kse

iTrader: (1)

Hmmmm. Maybe there's a time element involved, Maksim2000. It would be cool if other people tried it both ways when they get a CEL. Then we might be able to establish a trend.

BTW, when you tried the brake trick, did you do it long enough for the brake lights to go out completely? Just curious.

Y2KevSE

iTrader: (13)

y2kse

iTrader: (1)

Yup. I'd call that a time element alright! And so much for the idea of a quick way to reset the ECU.

Oh well, it sounded like a good idea at the time.

Thanks, Kev.

mzmtg

iTrader: (11)

Since when does WOT and high speed constitute abuse?

y2kse

iTrader: (1)

Methinks you may have jumped to a hasty conclusion, mzmtg. Just because the Consult may be able to read certain conditions when a malfunction occurs doesn't necessarily mean that abuse caused the malfunction.

lcj2002se

So what is a ECU and what does it do????

y2kse

iTrader: (1)

Hi lcj2002se. Welcome.

Allow me to introduce you to some of the features of the 5th Gen Forum. First, I'd recommend that you take a look through the Frequently Asked Questions (FAQ) thread. Although you may not understand everything you read, you'll run into it if you stick around here long enough.

We use a lot of abbreviations around here. There's an excellent thread on Page 4 of the FAQs that lists the most common ones, including ECU.

FYI, the ECU is the brain of your Maxima.

Viciousss1

iTrader: (2)

If i did disconnect the battery and hooked it up the next day.
how would i know if the ECU was reset?

y2kse

iTrader: (1)

Depends on why you disconnected the ECU. If you did so to clear a SES light, you'd know it's reset when you reconnect your battery, start your car, and the SES light does not illuminate.

JMaster

Actually I tried this already on my 2K maxima cuz my "check engine soon" light came one. Doesn't work unfortunately.

Menasor

iTrader: (2)

I don't see WOT and high speed as abuse. I never said that. If your the type that races a lot and does burn outs and stuff wouldn't that cause stress on your transmission and engine? I would think so. For example, let's say Racer X has a RSX and just loves to race. One day Racer X gets involved in a race with some other car and all the sudden his car, I don't know, blew a head gasket or messed up his clutch. So Racer X is concered that the damages will put a big dent in his wallet. But wait he figures I'll just take out my mods and take it to the dealer and tell them that it just happen out of the blue. Racer X gets to the dealer and tells the service writer that he was just driving the speed limit and all of the sudden he car is messed up and wants it repair under warranty. What I was saying is I heard that it is possible for the technician to know at what speed he was going at the time the problem occured, at what rpm, gear, mph, temp. of the car, etc. SO you want to reset the ECU anytime you are taking the car to the dealer. But I read that resetting the ECU isn't necessarily reset when disconnecting the battery for an extended period of time. So I ask for what some of your guys thoughts on this was.

VQMaster

I have tried leaving the battery disconnected over night a couple of times and the light still keeps coming back on. Do any one you have any ideas. The pipe sounds great but is it causing any damage? Sensors where put back in place. However, I do hear a whistling noise at high rpm. May have exhaust leak. Would this trigger the light and if the light stays on could it cause damagae to anything in the long run?

victor

iTrader: (1)

maybe the thing with the 24 hours and resetting the DTC is because of the backup battery trying to save the memory for diagnostic purposes.